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  • Need help recovering a corrupt SQL database

    - by user570079
    I have a very special case that I have been working on for several days. I have a very large SQL Server 2008 database (about 2 TB) that contains 500 filegroups to support very large partitioned tables. Recently we had a catastophic failure on one of the drive and lost several filegroups and the database became in-accessible. We have been doing filegroup backups on a daily basis, but due to other issues, we lost our most recent backup of the log and the primary filegroup. We have all the data backed up but the primary filegroup backup is old. There have been no schema changes since the primary filegroup backup, but the lsn's are now all out of sync and we cannot recover the data. I have tried everything I could think of (and have tried just about every trick and hack I could google) but I still end up at the same point where I get messages saying that the files for filegroup x do not match the primary filegroup. I am now at the point of trying to edit the system tables (we have a separate temporary environment to do this so we are not worried about corrupting any production databases). I have tried updated sys.sysdbreg, sys.sysbrickfiles, and sys.sysprufiles to try to trick SQL into thinking all the files are online, but a "Select * From OPENROWSET(TABLE DBPROP, 5)" shows a different database state from what I see in sys.sysdbreg. I am now thinking I need to somehow edit the headers of the actual data files to try to line up the lsn's with the primary. I appreciate any help anyone can give me here, but please do not respond with things like "you are not supposed to do edit mdf, ndf files...." or "see msdn article....", etc. This is an advanced emergency case and I need a real hack so we can just get to the data in this corrupt database and export to a fresh new database. I know there is a way to do this, but not knowing what the DBPROP system functions does (i.e. does it look at system tables or does it actually open the file) is keeping me from trying to figure out how to fool SQL into allowing me to read these files. Thanks for any help.

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  • TrueCrypt partition will no longer mount

    - by sparkyuiop
    I am hoping for some advice to help me out of my situation, with luck. I have a computer running Windows 7 Ultimate x64 with 3 hard disks installed. On my 2TB hard disk 2 (non-system disk) I have 4 partitions. One is for music, another for video, a downloads partition and a 500GB RAW Truecrypt encrypted partition / volume that I had setup to mount with 4 photographs used as keyfiles. The 4 photographs are located in my 'Documents' partition which is one of four partitions on my 1.5TB hard disk 1 (non-system disk) When I setup the disk encryption I did not (I'm 99% sure) create a password, I only used the 4 photograph keyfiles to mount the volume. Recently my 1TB hard disk 0 (system / boot) started to fail so I decided to replace it. I was going to clone the old disk to a new disk but decided that a fresh installation would be more beneficial. Once I had transferred all the required 'User Data' from my old hard disk 0 (C: disk) I discarded it. I reinstalled Truecrypt, pointed to the partition, selected my 4 keyfiles photographs and I mounted my encrypted volume with no issues. In fact I mounted it several times after re-installing Windows and after reboots. Now all of a sudden when I try and mount it I get the message "incorrect keyfile(s) and/or password or not a Truecrypt volume". Now I am not sure why this happened as I do not recall exactly what I did between last mounting the volume successfully and it not mounting. Here are some of the possible things I may have done to cause it to stop working but I am at a loss as to where to start to try and resolve the problem. 1. I had swapped the drive letters to a preferred order. 2. I possibly swapped the physical SATA connectors on the mainboard. 3. I enabled 'Hot Plugging' for the two non-system hard disk SATA ports and the DVD SATA port in the BIOS. I have tried changing the encrypted partition drive letter as suggested in another post but this does not help. On my old system the encrypted drive was drive "X". I have about tried it with all the other free drive letters but alas nothing changes. I do not recall what drive letter was allocated to the encrypted partition before I changed them all. I have not tried to change the letter back to what it possibly was to start with as I am happy with the current layout. I will try this is anyone thinks it would be worthwhile though. I do hope I have managed to convey my situation in an understandable manner and live in hope someone could help me recover years of personal files. Thank you very much for taking the time to read my post and for any suggestions you may offer. Regards Phillip Thorne (UK) Anyone???

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  • Cannot install mysql-server (5.5.22) on clean ubuntu 12.04 LTS server

    - by Christian
    I have a clean minimal install of Ubuntu 12.04 LTS server 64-bit (just a root user and nothing alse installed). I tried to install the mysql-server with the following command: apt-get install mysql-server The installation aborts with the following error: The following NEW packages will be installed: libdbd-mysql-perl{a} libmysqlclient18{a} mysql-client mysql-client-5.5{a} mysql-client-core-5.5{a} mysql-common{a} mysql-server mysql-server-5.5{a} mysql-server-core-5.5{a} 0 packages upgraded, 9 newly installed, 0 to remove and 0 not upgraded. Need to get 11.7 kB/26.2 MB of archives. After unpacking 94.5 MB will be used. Do you want to continue? [Y/n/?] y Get: 1 http://mirror.eu.oneandone.net/ubuntu/ubuntu/ precise/main mysql-client all 5.5.22-0ubuntu1 [11.7 kB] Fetched 11.7 kB in 0s (567 kB/s) Preconfiguring packages ... Selecting previously unselected package mysql-common. (Reading database ... 54008 files and directories currently installed.) Unpacking mysql-common (from .../mysql-common_5.5.22-0ubuntu1_all.deb) ... Selecting previously unselected package libmysqlclient18. Unpacking libmysqlclient18 (from .../libmysqlclient18_5.5.22-0ubuntu1_amd64.deb) ... Selecting previously unselected package libdbd-mysql-perl. Unpacking libdbd-mysql-perl (from .../libdbd-mysql-perl_4.020-1build2_amd64.deb) ... Selecting previously unselected package mysql-client-core-5.5. Unpacking mysql-client-core-5.5 (from .../mysql-client-core-5.5_5.5.22-0ubuntu1_amd64.deb) ... Selecting previously unselected package mysql-client-5.5. Unpacking mysql-client-5.5 (from .../mysql-client-5.5_5.5.22-0ubuntu1_amd64.deb) ... Selecting previously unselected package mysql-server-core-5.5. Unpacking mysql-server-core-5.5 (from .../mysql-server-core-5.5_5.5.22-0ubuntu1_amd64.deb) ... Processing triggers for man-db ... Setting up mysql-common (5.5.22-0ubuntu1) ... Selecting previously unselected package mysql-server-5.5. (Reading database ... 54189 files and directories currently installed.) Unpacking mysql-server-5.5 (from .../mysql-server-5.5_5.5.22-0ubuntu1_amd64.deb) ... Selecting previously unselected package mysql-client. Unpacking mysql-client (from .../mysql-client_5.5.22-0ubuntu1_all.deb) ... Selecting previously unselected package mysql-server. Unpacking mysql-server (from .../mysql-server_5.5.22-0ubuntu1_all.deb) ... Processing triggers for ureadahead ... Processing triggers for man-db ... Setting up libmysqlclient18 (5.5.22-0ubuntu1) ... Setting up libdbd-mysql-perl (4.020-1build2) ... Setting up mysql-client-core-5.5 (5.5.22-0ubuntu1) ... Setting up mysql-client-5.5 (5.5.22-0ubuntu1) ... Setting up mysql-server-core-5.5 (5.5.22-0ubuntu1) ... Setting up mysql-server-5.5 (5.5.22-0ubuntu1) ... 120502 10:17:41 [Note] Plugin 'FEDERATED' is disabled. 120502 10:17:41 InnoDB: The InnoDB memory heap is disabled 120502 10:17:41 InnoDB: Mutexes and rw_locks use GCC atomic builtins 120502 10:17:41 InnoDB: Compressed tables use zlib 1.2.3.4 120502 10:17:41 InnoDB: Initializing buffer pool, size = 128.0M 120502 10:17:41 InnoDB: Completed initialization of buffer pool 120502 10:17:41 InnoDB: highest supported file format is Barracuda. 120502 10:17:41 InnoDB: Waiting for the background threads to start 120502 10:17:42 InnoDB: 1.1.8 started; log sequence number 1595675 120502 10:17:42 InnoDB: Starting shutdown... 120502 10:17:42 InnoDB: Shutdown completed; log sequence number 1595675 start: Job failed to start invoke-rc.d: initscript mysql, action "start" failed. dpkg: error processing mysql-server-5.5 (--configure): subprocess installed post-installation script returned error exit status 1 No apport report written because MaxReports is reached already Setting up mysql-client (5.5.22-0ubuntu1) ... dpkg: dependency problems prevent configuration of mysql-server: mysql-server depends on mysql-server-5.5; however: Package mysql-server-5.5 is not configured yet. dpkg: error processing mysql-server (--configure): dependency problems - leaving unconfigured No apport report written because MaxReports is reached already Processing triggers for libc-bin ... ldconfig deferred processing now taking place Errors were encountered while processing: mysql-server-5.5 mysql-server E: Sub-process /usr/bin/dpkg returned an error code (1) A package failed to install. Trying to recover: Setting up mysql-server-5.5 (5.5.22-0ubuntu1) ... start: Job failed to start invoke-rc.d: initscript mysql, action "start" failed. dpkg: error processing mysql-server-5.5 (--configure): subprocess installed post-installation script returned error exit status 1 dpkg: dependency problems prevent configuration of mysql-server: mysql-server depends on mysql-server-5.5; however: Package mysql-server-5.5 is not configured yet. dpkg: error processing mysql-server (--configure): dependency problems - leaving unconfigured Errors were encountered while processing: mysql-server-5.5 mysql-server I am completely lost because I have tried everything on the web to solve my problem (clearning the install, reconfiguring with dpkg, manually editing the my.cnf). I also set up a new clean install but nothing helped. What am I doing wrong? New information: The file /var/log/upstart/mysql.log contains the following error after the installation: AppArmor parser error for /etc/apparmor.d/usr.sbin.mysqld in /etc/apparmor.d/tunables/global at line 17: Could not open 'tunables/proc'

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  • MySQL 5.5 - Lost connection to MySQL server during query

    - by bully
    I have an Ubuntu 12.04 LTS server running at a german hoster (virtualized system). # uname -a Linux ... 3.2.0-27-generic #43-Ubuntu SMP Fri Jul 6 14:25:57 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux I want to migrate a Web CMS system, called Contao. It's not my first migration, but my first migration having connection issues with mysql. Migration went successfully, I have the same Contao version running (it's more or less just copy / paste). For the database behind, I did: apt-get install mysql-server phpmyadmin I set a root password and added a user for the CMS which has enough rights on its own database (and only its database) for doing the stuff it has to do. Data import via phpmyadmin worked just fine. I can access the backend of the CMS (which needs to deal with the database already). If I try to access the frontend now, I get the following error: Fatal error: Uncaught exception Exception with message Query error: Lost connection to MySQL server during query (<query statement here, nothing special, just a select>) thrown in /var/www/system/libraries/Database.php on line 686 (Keep in mind: I can access mysql with phpmyadmin and through the backend, working like a charme, it's just the frontend call causing errors). If I spam F5 in my browser I can sometimes even kill the mysql deamon. If I run # mysqld --log-warnings=2 I get this: ... 120921 7:57:31 [Note] mysqld: ready for connections. Version: '5.5.24-0ubuntu0.12.04.1' socket: '/var/run/mysqld/mysqld.sock' port: 3306 (Ubuntu) 05:57:37 UTC - mysqld got signal 4 ; This could be because you hit a bug. It is also possible that this binary or one of the libraries it was linked against is corrupt, improperly built, or misconfigured. This error can also be caused by malfunctioning hardware. We will try our best to scrape up some info that will hopefully help diagnose the problem, but since we have already crashed, something is definitely wrong and this may fail. key_buffer_size=16777216 read_buffer_size=131072 max_used_connections=1 max_threads=151 thread_count=1 connection_count=1 It is possible that mysqld could use up to key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 346679 K bytes of memory Hope that's ok; if not, decrease some variables in the equation. Thread pointer: 0x7f1485db3b20 Attempting backtrace. You can use the following information to find out where mysqld died. If you see no messages after this, something went terribly wrong... stack_bottom = 7f1480041e60 thread_stack 0x30000 mysqld(my_print_stacktrace+0x29)[0x7f1483b96459] mysqld(handle_fatal_signal+0x483)[0x7f1483a5c1d3] /lib/x86_64-linux-gnu/libpthread.so.0(+0xfcb0)[0x7f1482797cb0] /lib/x86_64-linux-gnu/libm.so.6(+0x42e11)[0x7f14821cae11] mysqld(_ZN10SQL_SELECT17test_quick_selectEP3THD6BitmapILj64EEyyb+0x1368)[0x7f1483b26cb8] mysqld(+0x33116a)[0x7f148397916a] mysqld(_ZN4JOIN8optimizeEv+0x558)[0x7f148397d3e8] mysqld(_Z12mysql_selectP3THDPPP4ItemP10TABLE_LISTjR4ListIS1_ES2_jP8st_orderSB_S2_SB_yP13select_resultP18st_select_lex_unitP13st_select_lex+0xdd)[0x7f148397fd7d] mysqld(_Z13handle_selectP3THDP3LEXP13select_resultm+0x17c)[0x7f1483985d2c] mysqld(+0x2f4524)[0x7f148393c524] mysqld(_Z21mysql_execute_commandP3THD+0x293e)[0x7f14839451de] mysqld(_Z11mysql_parseP3THDPcjP12Parser_state+0x10f)[0x7f1483948bef] mysqld(_Z16dispatch_command19enum_server_commandP3THDPcj+0x1365)[0x7f148394a025] mysqld(_Z24do_handle_one_connectionP3THD+0x1bd)[0x7f14839ec7cd] mysqld(handle_one_connection+0x50)[0x7f14839ec830] /lib/x86_64-linux-gnu/libpthread.so.0(+0x7e9a)[0x7f148278fe9a] /lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7f1481eba4bd] Trying to get some variables. Some pointers may be invalid and cause the dump to abort. Query (7f1464004b60): is an invalid pointer Connection ID (thread ID): 1 Status: NOT_KILLED From /var/log/syslog: Sep 21 07:17:01 s16477249 CRON[23855]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly) Sep 21 07:18:51 s16477249 kernel: [231923.349159] type=1400 audit(1348204731.333:70): apparmor="STATUS" operation="profile_replace" name="/usr/sbin/mysqld" pid=23946 comm="apparmor_parser" Sep 21 07:18:53 s16477249 /etc/mysql/debian-start[23990]: Upgrading MySQL tables if necessary. Sep 21 07:18:53 s16477249 /etc/mysql/debian-start[23993]: /usr/bin/mysql_upgrade: the '--basedir' option is always ignored Sep 21 07:18:53 s16477249 /etc/mysql/debian-start[23993]: Looking for 'mysql' as: /usr/bin/mysql Sep 21 07:18:53 s16477249 /etc/mysql/debian-start[23993]: Looking for 'mysqlcheck' as: /usr/bin/mysqlcheck Sep 21 07:18:53 s16477249 /etc/mysql/debian-start[23993]: This installation of MySQL is already upgraded to 5.5.24, use --force if you still need to run mysql_upgrade Sep 21 07:18:53 s16477249 /etc/mysql/debian-start[24004]: Checking for insecure root accounts. Sep 21 07:18:53 s16477249 /etc/mysql/debian-start[24009]: Triggering myisam-recover for all MyISAM tables I'm using MyISAM tables all over, nothing with InnoDB there. Starting / stopping mysql is done via sudo service mysql start sudo service mysql stop After using google a little bit, I experimented a little bit with timeouts, correct socket path in the /etc/mysql/my.cnf file, but nothing helped. There are some old (from 2008) Gentoo bugs, where re-compiling just solved the problem. I already re-installed mysql via: sudo apt-get remove mysql-server mysql-common sudo apt-get autoremove sudo apt-get install mysql-server without any results. This is the first time I'm running into this problem, and I'm not very experienced with this kind of mysql 'administration'. So mainly, I want to know if anyone of you could help me out please :) Is it a mysql bug? Is something broken in the Ubuntu repositories? Is this one of those misterious 'use-tcp-connection-instead-of-socket-stuff-because-there-are-problems-on-virtualized-machines-with-sockets'-problem? Or am I completly on the wrong way and I just miss-configured something? Remember, phpmyadmin and access to the backend (which uses the database, too) is just fine. Maybe something with Apache? What can I do? Any help is appreciated, so thanks in advance :)

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  • mysql not starting

    - by Eiriks
    I have a server running on rackspace.com, it been running for about a year (collecting data for a project) and no problems. Now it seems mysql froze (could not connect either through ssh command line, remote app (sequel pro) or web (pages using the db just froze). I got a bit eager to fix this quick and rebooted the virtual server, running ubuntu 10.10. It is a small virtual LAMP server (10gig storage - I'm only using 1, 256mb ram -has not been a problem). Now after the reboot, I cannot get mysql to start again. service mysql status mysql stop/waiting I believe this just means mysql is not running. How do I get this running again? service mysql start start: Job failed to start No. Just typing 'mysql' gives: mysql ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (111) There is a .sock file in this folder, 'ls -l' gives: srwxrwxrwx 1 mysql mysql 0 2012-12-01 17:20 mysqld.sock From googleing this for a while now, I see that many talk about the logfile and my.cnf. Logs Not sure witch ones I should look at. This log-file is empty: 'var/log/mysql/error.log', so is the 'var/log/mysql.err' and 'var/log/mysql.log'. my.cnf is located in '/etc/mysql' and looks like this. Can't see anything clearly wrong with it either. # # The MySQL database server configuration file. # # You can copy this to one of: # - "/etc/mysql/my.cnf" to set global options, # - "~/.my.cnf" to set user-specific options. # # One can use all long options that the program supports. # Run program with --help to get a list of available options and with # --print-defaults to see which it would actually understand and use. # # For explanations see # http://dev.mysql.com/doc/mysql/en/server-system-variables.html # This will be passed to all mysql clients # It has been reported that passwords should be enclosed with ticks/quotes # escpecially if they contain "#" chars... # Remember to edit /etc/mysql/debian.cnf when changing the socket location. [client] port = 3306 socket = /var/run/mysqld/mysqld.sock # Here is entries for some specific programs # The following values assume you have at least 32M ram # This was formally known as [safe_mysqld]. Both versions are currently parsed. [mysqld_safe] socket = /var/run/mysqld/mysqld.sock nice = 0 [mysqld] # # * Basic Settings # # # * IMPORTANT # If you make changes to these settings and your system uses apparmor, you may # also need to also adjust /etc/apparmor.d/usr.sbin.mysqld. # user = mysql socket = /var/run/mysqld/mysqld.sock port = 3306 basedir = /usr datadir = /var/lib/mysql tmpdir = /tmp skip-external-locking # # Instead of skip-networking the default is now to listen only on # localhost which is more compatible and is not less secure. bind-address = 127.0.0.1 # # * Fine Tuning # key_buffer = 16M max_allowed_packet = 16M thread_stack = 192K thread_cache_size = 8 # This replaces the startup script and checks MyISAM tables if needed # the first time they are touched myisam-recover = BACKUP #max_connections = 100 #table_cache = 64 #thread_concurrency = 10 # # * Query Cache Configuration # query_cache_limit = 1M query_cache_size = 16M # # * Logging and Replication # # Both location gets rotated by the cronjob. # Be aware that this log type is a performance killer. # As of 5.1 you can enable the log at runtime! #general_log_file = /var/log/mysql/mysql.log #general_log = 1 log_error = /var/log/mysql/error.log # Here you can see queries with especially long duration #log_slow_queries = /var/log/mysql/mysql-slow.log #long_query_time = 2 #log-queries-not-using-indexes # # The following can be used as easy to replay backup logs or for replication. # note: if you are setting up a replication slave, see README.Debian about # other settings you may need to change. #server-id = 1 #log_bin = /var/log/mysql/mysql-bin.log expire_logs_days = 10 max_binlog_size = 100M #binlog_do_db = include_database_name #binlog_ignore_db = include_database_name # # * InnoDB # # InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/. # Read the manual for more InnoDB related options. There are many! # # * Security Features # # Read the manual, too, if you want chroot! # chroot = /var/lib/mysql/ # # For generating SSL certificates I recommend the OpenSSL GUI "tinyca". # # ssl-ca=/etc/mysql/cacert.pem # ssl-cert=/etc/mysql/server-cert.pem # ssl-key=/etc/mysql/server-key.pem [mysqldump] quick quote-names max_allowed_packet = 16M [mysql] #no-auto-rehash # faster start of mysql but no tab completition [isamchk] key_buffer = 16M # # * IMPORTANT: Additional settings that can override those from this file! # The files must end with '.cnf', otherwise they'll be ignored. # !includedir /etc/mysql/conf.d/ I need the data in the database (so i'd like to avoid reinstalling), and I need it back up running again. All hint, tips and solutions are welcomed and appreciated.

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  • 8 Backup Tools Explained for Windows 7 and 8

    - by Chris Hoffman
    Backups on Windows can be confusing. Whether you’re using Windows 7 or 8, you have quite a few integrated backup tools to think about. Windows 8 made quite a few changes, too. You can also use third-party backup software, whether you want to back up to an external drive or back up your files to online storage. We won’t cover third-party tools here — just the ones built into Windows. Backup and Restore on Windows 7 Windows 7 has its own Backup and Restore feature that lets you create backups manually or on a schedule. You’ll find it under Backup and Restore in the Control Panel. The original version of Windows 8 still contained this tool, and named it Windows 7 File Recovery. This allowed former Windows 7 users to restore files from those old Windows 7 backups or keep using the familiar backup tool for a little while. Windows 7 File Recovery was removed in Windows 8.1. System Restore System Restore on both Windows 7 and 8 functions as a sort of automatic system backup feature. It creates backup copies of important system and program files on a schedule or when you perform certain tasks, such as installing a hardware driver. If system files become corrupted or your computer’s software becomes unstable, you can use System Restore to restore your system and program files from a System Restore point. This isn’t a way to back up your personal files. It’s more of a troubleshooting feature that uses backups to restore your system to its previous working state. Previous Versions on Windows 7 Windows 7′s Previous Versions feature allows you to restore older versions of files — or deleted files. These files can come from backups created with Windows 7′s Backup and Restore feature, but they can also come from System Restore points. When Windows 7 creates a System Restore point, it will sometimes contain your personal files. Previous Versions allows you to extract these personal files from restore points. This only applies to Windows 7. On Windows 8, System Restore won’t create backup copies of your personal files. The Previous Versions feature was removed on Windows 8. File History Windows 8 replaced Windows 7′s backup tools with File History, although this feature isn’t enabled by default. File History is designed to be a simple, easy way to create backups of your data files on an external drive or network location. File History replaces both Windows 7′s Backup and Previous Versions features. Windows System Restore won’t create copies of personal files on Windows 8. This means you can’t actually recover older versions of files until you enable File History yourself — it isn’t enabled by default. System Image Backups Windows also allows you to create system image backups. These are backup images of your entire operating system, including your system files, installed programs, and personal files. This feature was included in both Windows 7 and Windows 8, but it was hidden in the preview versions of Windows 8.1. After many user complaints, it was restored and is still available in the final version of Windows 8.1 — click System Image Backup on the File History Control Panel. Storage Space Mirroring Windows 8′s Storage Spaces feature allows you to set up RAID-like features in software. For example, you can use Storage Space to set up two hard disks of the same size in a mirroring configuration. They’ll appear as a single drive in Windows. When you write to this virtual drive, the files will be saved to both physical drives. If one drive fails, your files will still be available on the other drive. This isn’t a good long-term backup solution, but it is a way of ensuring you won’t lose important files if a single drive fails. Microsoft Account Settings Backup Windows 8 and 8.1 allow you to back up a variety of system settings — including personalization, desktop, and input settings. If you’re signing in with a Microsoft account, OneDrive settings backup is enabled automatically. This feature can be controlled under OneDrive > Sync settings in the PC settings app. This feature only backs up a few settings. It’s really more of a way to sync settings between devices. OneDrive Cloud Storage Microsoft hasn’t been talking much about File History since Windows 8 was released. That’s because they want people to use OneDrive instead. OneDrive — formerly known as SkyDrive — was added to the Windows desktop in Windows 8.1. Save your files here and they’ll be stored online tied to your Microsoft account. You can then sign in on any other computer, smartphone, tablet, or even via the web and access your files. Microsoft wants typical PC users “backing up” their files with OneDrive so they’ll be available on any device. You don’t have to worry about all these features. Just choose a backup strategy to ensure your files are safe if your computer’s hard disk fails you. Whether it’s an integrated backup tool or a third-party backup application, be sure to back up your files.

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  • SQL SERVER – Beginning of SQL Server Architecture – Terminology – Guest Post

    - by pinaldave
    SQL Server Architecture is a very deep subject. Covering it in a single post is an almost impossible task. However, this subject is very popular topic among beginners and advanced users.  I have requested my friend Anil Kumar who is expert in SQL Domain to help me write  a simple post about Beginning SQL Server Architecture. As stated earlier this subject is very deep subject and in this first article series he has covered basic terminologies. In future article he will explore the subject further down. Anil Kumar Yadav is Trainer, SQL Domain, Koenig Solutions. Koenig is a premier IT training firm that provides several IT certifications, such as Oracle 11g, Server+, RHCA, SQL Server Training, Prince2 Foundation etc. In this Article we will discuss about MS SQL Server architecture. The major components of SQL Server are: Relational Engine Storage Engine SQL OS Now we will discuss and understand each one of them. 1) Relational Engine: Also called as the query processor, Relational Engine includes the components of SQL Server that determine what your query exactly needs to do and the best way to do it. It manages the execution of queries as it requests data from the storage engine and processes the results returned. Different Tasks of Relational Engine: Query Processing Memory Management Thread and Task Management Buffer Management Distributed Query Processing 2) Storage Engine: Storage Engine is responsible for storage and retrieval of the data on to the storage system (Disk, SAN etc.). to understand more, let’s focus on the following diagram. When we talk about any database in SQL server, there are 2 types of files that are created at the disk level – Data file and Log file. Data file physically stores the data in data pages. Log files that are also known as write ahead logs, are used for storing transactions performed on the database. Let’s understand data file and log file in more details: Data File: Data File stores data in the form of Data Page (8KB) and these data pages are logically organized in extents. Extents: Extents are logical units in the database. They are a combination of 8 data pages i.e. 64 KB forms an extent. Extents can be of two types, Mixed and Uniform. Mixed extents hold different types of pages like index, System, Object data etc. On the other hand, Uniform extents are dedicated to only one type. Pages: As we should know what type of data pages can be stored in SQL Server, below mentioned are some of them: Data Page: It holds the data entered by the user but not the data which is of type text, ntext, nvarchar(max), varchar(max), varbinary(max), image and xml data. Index: It stores the index entries. Text/Image: It stores LOB ( Large Object data) like text, ntext, varchar(max), nvarchar(max),  varbinary(max), image and xml data. GAM & SGAM (Global Allocation Map & Shared Global Allocation Map): They are used for saving information related to the allocation of extents. PFS (Page Free Space): Information related to page allocation and unused space available on pages. IAM (Index Allocation Map): Information pertaining to extents that are used by a table or index per allocation unit. BCM (Bulk Changed Map): Keeps information about the extents changed in a Bulk Operation. DCM (Differential Change Map): This is the information of extents that have modified since the last BACKUP DATABASE statement as per allocation unit. Log File: It also known as write ahead log. It stores modification to the database (DML and DDL). Sufficient information is logged to be able to: Roll back transactions if requested Recover the database in case of failure Write Ahead Logging is used to create log entries Transaction logs are written in chronological order in a circular way Truncation policy for logs is based on the recovery model SQL OS: This lies between the host machine (Windows OS) and SQL Server. All the activities performed on database engine are taken care of by SQL OS. It is a highly configurable operating system with powerful API (application programming interface), enabling automatic locality and advanced parallelism. SQL OS provides various operating system services, such as memory management deals with buffer pool, log buffer and deadlock detection using the blocking and locking structure. Other services include exception handling, hosting for external components like Common Language Runtime, CLR etc. I guess this brief article gives you an idea about the various terminologies used related to SQL Server Architecture. In future articles we will explore them further. Guest Author  The author of the article is Anil Kumar Yadav is Trainer, SQL Domain, Koenig Solutions. Koenig is a premier IT training firm that provides several IT certifications, such as Oracle 11g, Server+, RHCA, SQL Server Training, Prince2 Foundation etc. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Security, SQL Server, SQL Tips and Tricks, SQL Training, T SQL, Technology

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  • ComboBox Control using silverlight

    - by Aamir Hasan
    DropDown.zip (135.33 kb) LiveDemo Introduction In this article i am  going to explore some of the features of the ComboBox.ComboBox makes the collection visible and allows users to pick an item from the collection.After its first initialization, no matter if you bind a new datasource with fewer or more elements, the dropdown persists its original height.One workaround is the following:1. store the Properties from the original ComboBox2. delete the ComboBox removing it from its container3. create a new ComboBox and place it in the container4. recover the stores Properties5. bind the new DataSource to the newly created combobox Creating Silverlight ProjectCreate a new Silverlight 3 Project in VS 2008. Name it as ComboBoxtSample. Simple Data BindingAdd System.Windows.Control.Data reference to the Silverlight project. Silverlight UserControl Add a new page to display Bus data using DataGrid. Following shows Bus column XAML snippet:The ComboBox element represents a ComboBox control in XAML.  <ComboBox></ComboBox>ComboBox XAML        <StackPanel Orientation="Vertical">            <ComboBox Width="120" Height="30" x:Name="DaysDropDownList" DisplayMemberPath="Name">                <!--<ComboBox.ItemTemplate>                    <DataTemplate>                        <StackPanel Orientation="Horizontal">                            <TextBlock Text="{Binding Path=Name}" FontWeight="Bold"></TextBlock>                            <TextBlock Text=", "></TextBlock>                            <TextBlock Text="{Binding Path=ID}"></TextBlock>                        </StackPanel>                    </DataTemplate>                </ComboBox.ItemTemplate>-->            </ComboBox>        </StackPanel>   The following code below is an example implementation Combobox control support data binding     1 By setting the DisplayMemberPath property you can specify which data item in your data you want displayed in the ComboBox.    2 Setting the SelectedIndex allows you to specify which item in the ComboBox you want selected. Business Object public class Bus { public string Name { get; set; } public float Price { get; set; } }   Data Binding private List populatedlistBus() { listBus = new List(); listBus.Add(new Bus() {Name = "Bus 1", Price = 55f }); listBus.Add(new Bus() { Name = "Bus 2", Price = 55.7f }); listBus.Add(new Bus() { Name = "Bus 3", Price = 2f }); listBus.Add(new Bus() { Name = "Bus 4", Price = 6f }); listBus.Add(new Bus() { Name = "Bus 5", Price = 9F }); listBus.Add(new Bus() { Name = "Bus 6", Price = 10.1f }); return listBus; }   The following line of code sets the ItemsSource property of a ComboBox. DaysDropDownList.ItemsSource = populatedlistBus(); Output I hope you enjoyed this simple Silverlight example Conclusion In this article, we saw how data binding works in ComboBox.You learnt how to work with the ComboBox control in Silverlight.

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  • Ubuntu 11 and 12 initially fast but later bogs down, CPU pegged

    - by uos??
    I started with Ubuntu 11 a few weeks ago. It's on a DELL M4300 with a OCZ SSD. Default setup, except that I've installed the proprietary NVIDIA graphics and BROADCOM wireless drivers. Dual boot with Windows. If I cold boot into Ubuntu, it is very fast, just like the Windows experience that I'm used to. But SOMETHING happens, and I haven't yet determined what, but the system gets incredibly slow and stays that way. At first I thought it had to do with Adobe Flash because it seemed to be triggered by sites with Flash. But then I removed Flash and the problem remains. I thought it was just an overheating problem, but I've now upgraded to 12.04 which supposedly fixes the overheating problems I've read about. Perhaps the heat situation was brought on by Flash in my early cases? So I installed Jupiter for CPU management, but the thermometer reports a familiar Windows-side temperature of 53 degrees Celsius. Switching Jupiter to lower performance doesn't help. When I check the System Monitor application, sorting by CPU usage, there are no obvious problem processes. However, in the graphs tab, both CPU cores are pegged at 100%! I notice that the slowness seems to be similar to the extremely bad performance I got prior to installing the NVIDIA drivers. I'm not sure if that helps. This is the strangest part to me - although the temperature seems OK, even after rebooting, the system remains slow - starting with GRUB2 which is very noticeably delayed, all the way through to either Ubuntu or Windows! That's right, even the Windows side suffers effects and takes several minutes to complete booting whereas normally (with my SSD) it's ready to use in 15 seconds. The only way to fix it is to shutdown and let the parts cool down. Or maybe it just needs to completely power off and boot rather than a soft reboot, temperature has nothing to do with it? - is that possible? But know that I have never had this problem in Windows, even if Windows gets very hot (135 F) a reboot would be enough time for it to recover. For this reason, I don't think it's a heat thing, but I can't imagine what else could be surviving the reboot. I'm entirely updated - there are no pending updates. I have the Post-Release updates of NVIDIA too, btw. If this sounds CLOSE to something you know about, but one of the details doesn't line up exactly, it might be a mistake in my perception. Are there tests you can suggest to rule something out? Thanks! processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 23 model name : Intel(R) Core(TM)2 Duo CPU T9500 @ 2.60GHz stepping : 6 microcode : 0x60c cpu MHz : 800.000 cache size : 6144 KB physical id : 0 siblings : 2 core id : 0 cpu cores : 2 apicid : 0 initial apicid : 0 fpu : yes fpu_exception : yes cpuid level : 10 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx lm constant_tsc arch_perfmon pebs bts rep_good nopl aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm sse4_1 lahf_lm ida dts tpr_shadow vnmi flexpriority bogomips : 5187.00 clflush size : 64 cache_alignment : 64 address sizes : 36 bits physical, 48 bits virtual power management: processor : 1 vendor_id : GenuineIntel cpu family : 6 model : 23 model name : Intel(R) Core(TM)2 Duo CPU T9500 @ 2.60GHz stepping : 6 microcode : 0x60c cpu MHz : 800.000 cache size : 6144 KB physical id : 0 siblings : 2 core id : 1 cpu cores : 2 apicid : 1 initial apicid : 1 fpu : yes fpu_exception : yes cpuid level : 10 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx lm constant_tsc arch_perfmon pebs bts rep_good nopl aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm sse4_1 lahf_lm ida dts tpr_shadow vnmi flexpriority bogomips : 5186.94 clflush size : 64 cache_alignment : 64 address sizes : 36 bits physical, 48 bits virtual power management: (Redundant figures removed. You can view them in the edits if they are still relevant) ps: %CPU PID USER COMMAND 9.4 2399 jason gnome-terminal 6.2 2408 jason bash 17.3 1117 root /usr/bin/X :0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch -background none 13.7 1667 jason compiz 1.3 1960 jason /usr/lib/unity/unity-panel-service 1.3 1697 jason python /usr/bin/jupiter 0.9 1964 jason /usr/lib/indicator-appmenu/hud-service 0.6 1689 jason nautilus -n 0.4 1458 jason //bin/dbus-daemon --fork --print-pid 5 --print-address 7 --session I should highlight specifically that GRUB2 can also be very slow. I don't know the relationship of which scenarios GRUB2 is also slow, but WHEN it is slow, it is slow both before the menu appears and after the selection is made - although for the diagnosis of GRUB2 it is harder for me to tell what the normal speeds should be. With SSD, I would expect that GRUB2 could load instantly, and that the GRUB2 purple would disappear instantly after the selection. The only delay to be expected is the change in graphics modes (though I couldn't guess why that ever requires any noticeable time)

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  • SQLAuthority News – Storing Data and Files in Cloud – Dropbox – Personal Technology Tip

    - by pinaldave
    I thought long and hard about doing a Personal Technology Tips series for this blog.  I have so many tips I’d like to share.  I am on my computer almost all day, every day, so I have a treasure trove of interesting tidbits I like to share if given the chance.  The only thing holding me back – which tip to share first?  The first tip obviously has the weight of seeming like the most important.  But this would mean choosing amongst my favorite tricks and shortcuts.  This is a hard task. Source: Dropbox.com My Dropbox I have finally decided, though, and have determined that the first Personal Technology Tip may not be the most secret or even trickier to master – in fact, it is probably the easiest.  My today’s Personal Technology Tip is Dropbox. I hope that all of you are nodding along in recognition right now.  If you do not use Dropbox, or have not even heard of it before, get on the internet and find their site.  You won’t be disappointed.  A quick recap for those in the dark: Dropbox is an online storage site with a lot of additional syncing and cloud-computing capabilities.  Now that we’ve covered the basics, let’s explore some of my favorite options in Dropbox. Collaborate with All The first thing I love about Dropbox is the ability it gives you to collaborate with others.  You can share files easily with other Dropbox users, and they can alter them, share them with you, all while keeping track of different versions in on easy place.  I’d like to see anyone try to accomplish that key idea – “easily” – using e-mail versions and multiple computers.  It’s even difficult to accomplish using a shared network. Afraid that this kind of ease looks too good to be true?  Afraid that maybe there isn’t enough storage space, or the user interface is confusing?  Think again.  There is plenty of space – you can get 2 GB with just a free account, and upgrades are inexpensive and go up to 100 GB of storage.  And the user interface is so easy that anyone can learn to use it. What I use Dropbox for I love Dropbox because I give a lot of presentations and often they are far from home.  I can keep my presentations on Dropbox and have easy access to them anywhere, without needing to have my whole computer with me.  This is just one small way that you can use Dropbox. You can sync your entire hard drive, or hard drives if you have multiple computers (home, work, office, shared), and you can set Dropbox to automatically sync files on a certain timeline, or whenever Dropbox notices that they’ve been changed. Why I love Dropbox Dropbox has plenty of storage, but 2 GB still has a hard time competing with the average desktop’s storage space.  So what if you want to sync most of your files, but only the ones you use the most and share between work and home, and not all your files (especially large files like pictures and videos)?  You can use selective sync to choose which files to sync. Above all, my favorite feature is LanSync.  Dropbox will search your Local Area Network (LAN) for new files and sync them to Dropbox, as well as downloading the new version to all the shared files across the network.  That means that if move around on different computers at work or at home, you will have the same version of the file every time.  Or, other users on the LAN will have access to the new version, which makes collaboration extremely easy. Ref: rzfeeser.com Dropbox has so many other features that I feel like I could create a Personal Technology Tips series devoted entirely to Dropbox.  I’m going to create a bullet list here to make things shorter, but I strongly encourage you to look further into these into options if it sounds like something you would use. Theft Recover Home Security File Hosting and Sharing Portable Dropbox Sync your iCal calendar Password Storage What is your favorite tool and why? I could go on and on, but I will end here.  In summary – I strongly encourage everyone to investigate Dropbox to see if it’s something they would find useful.  If you use Dropbox and know of a great feature I failed to mention, please share it with me, I’d love to hear how everyone uses this program. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology Tagged: Personal Technology

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  • Use Drive Mirroring for Instant Backup in Windows 7

    - by Trevor Bekolay
    Even with the best backup solution, a hard drive crash means you’ll lose a few hours of work. By enabling drive mirroring in Windows 7, you’ll always have an up-to-date copy of your data. Windows 7’s mirroring – which is only available in Professional, Enterprise, and Ultimate editions – is a software implementation of RAID 1, which means that two or more disks are holding the exact same data. The files are constantly kept in sync, so that if one of the disks fails, you won’t lose any data. Note that mirroring is not technically a backup solution, because if you accidentally delete a file, it’s gone from both hard disks (though you may be able to recover the file). As an additional caveat, having mirrored disks requires changing them to “dynamic disks,” which can only be read within modern versions of Windows (you may have problems working with a dynamic disk in other operating systems or in older versions of Windows). See this Wikipedia page for more information. You will need at least one empty disk to set up disk mirroring. We’ll show you how to mirror an existing disk (of equal or lesser size) without losing any data on the mirrored drive, and how to set up two empty disks as mirrored copies from the get-go. Mirroring an Existing Drive Click on the start button and type partitions in the search box. Click on the Create and format hard disk partitions entry that shows up. Alternatively, if you’ve disabled the search box, press Win+R to open the Run window and type in: diskmgmt.msc The Disk Management window will appear. We’ve got a small disk, labeled OldData, that we want to mirror in a second disk of the same size. Note: The disk that you will use to mirror the existing disk must be unallocated. If it is not, then right-click on it and select Delete Volume… to mark it as unallocated. This will destroy any data on that drive. Right-click on the existing disk that you want to mirror. Select Add Mirror…. Select the disk that you want to use to mirror the existing disk’s data and press Add Mirror. You will be warned that this process will change the existing disk from basic to dynamic. Note that this process will not delete any data on the disk! The new disk will be marked as a mirror, and it will starting copying data from the existing drive to the new one. Eventually the drives will be synced up (it can take a while), and any data added to the E: drive will exist on both physical hard drives. Setting Up Two New Drives as Mirrored If you have two new equal-sized drives, you can format them to be mirrored copies of each other from the get-go. Open the Disk Management window as described above. Make sure that the drives are unallocated. If they’re not, and you don’t need the data on either of them, right-click and select Delete volume…. Right-click on one of the unallocated drives and select New Mirrored Volume…. A wizard will pop up. Click Next. Click on the drives you want to hold the mirrored data and click Add. Note that you can add any number of drives. Click Next. Assign it a drive letter that makes sense, and then click Next. You’re limited to using the NTFS file system for mirrored drives, so enter a volume label, enable compression if you want, and then click Next. Click Finish to start formatting the drives. You will be warned that the new drives will be converted to dynamic disks. And that’s it! You now have two mirrored drives. Any files added to E: will reside on both physical disks, in case something happens to one of them. Conclusion While the switch from basic to dynamic disks can be a problem for people who dual-boot into another operating system, setting up drive mirroring is an easy way to make sure that your data can be recovered in case of a hard drive crash. Of course, even with drive mirroring, we advocate regular backups to external drives or online backup services. Similar Articles Productive Geek Tips Rebit Backup Software [Review]Disabling Instant Search in Outlook 2007Restore Files from Backups on Windows Home ServerSecond Copy 7 [Review]Backup Windows Home Server Folders to an External Hard Drive TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips CloudBerry Online Backup 1.5 for Windows Home Server Snagit 10 VMware Workstation 7 Acronis Online Backup Windows Firewall with Advanced Security – How To Guides Sculptris 1.0, 3D Drawing app AceStock, a Tiny Desktop Quote Monitor Gmail Button Addon (Firefox) Hyperwords addon (Firefox) Backup Outlook 2010

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  • IBM Keynote: (hardware,software)–>{IBM.java.patterns}

    - by Janice J. Heiss
    On Sunday evening, September 30, 2012, Jason McGee, IBM Distinguished Engineer and Chief Architect Cloud Computing, along with John Duimovich IBM Distinguished Engineer and Java CTO, gave an information- and idea-rich keynote that left Java developers with much to ponder.Their focus was on the challenges to make Java more efficient and productive given the hardware and software environments of 2012. “One idea that is very interesting is the idea of multi-tenancy,” said McGee, “and how we can move up the spectrum. In traditional systems, we ran applications on dedicated middleware, operating systems and hardware. A lot of customers still run that way. Now people introduce hardware virtualization and share the hardware. That is good but there is a lot more we can do. We can share middleware and the application itself.” McGee challenged developers to better enable the Java language to function in these higher density models. He spoke about the need to describe patterns that help us grasp the full environment that an application needs, whether it’s a web or full enterprise application. Developers need to understand the resources that an application interacts with in a way that is simple and straightforward. The task is to then automate that deployment so that the complexity of infrastructure can be by-passed and developers can live in a simpler world where the cloud can automatically configure the needed environment. McGee argued that the key, something IBM has been working on, is to use a simpler pattern that allows a cloud-based architecture to embrace the entire infrastructure required for an application and make it highly available, scalable and able to recover from failure. The cloud-based architecture would automate the complexity of setting up and managing the infrastructure. IBM has been trying to realize this vision for customers so they can describe their Java application environment simply and allow the cloud to automate the deployment and management of applications. “The point,” explained McGee, “is to package the executable used to describe applications, to drop it into a shared system and let that system provide some intelligence about how to deploy and manage those applications.”John Duimovich on Improvements in JavaMcGee then brought onstage IBM’s Distinguished Engineer and CTO for Java, John Duimovich, who showed the audience ways to deploy Java applications more efficiently.Duimovich explained that, “When you run lots of copies of Java in the cloud or any hypervisor virtualized system, there are a lot of duplications of code and jar files. IBM has a facility called ‘shared classes’ where we put shared code, read only artefacts in a cache that is sharable across hypervisors.” By putting JIT code in ahead of time, he explained that the application server will use 20% less memory and operate 30% faster.  He described another example of how the JVM allows for the maximum amount of sharing that manages the tenants and file sockets and memory use through throttling and control. Duimovich touched on the “thin is in” model and IBM’s Liberty Profile and lightweight runtime for the cloud, which allows for greater efficiency in interacting with the cloud.Duimovich discussed the confusion Java developers experience when, for example, the hypervisor tells them that that they have 8 and then 4 and then 16 cores. “Because hypervisors are virtualized, they can change based on resource needs across the hypervisor layer. You may have 10 instances of an operation system and you may need to reallocate memory, " explained Duimovich.  He showed how to resize LPARs, reallocate CPUs and migrate applications as needed. He explained how application servers can resize thread pools and better use resources based on information from the hypervisors.Java Challenges in Hardware and SoftwareMcGee ended the keynote with a summary of upcoming hardware and software challenges for the Java platform. He noted that one reason developers love Java is it allows them to ignore differences in hardware. He stated that the most important things happening in hardware were in network and storage – in developments such as the speed of SSD, the exploitation of high-speed, low-latency networking, and recent developments such as storage-class memory, and non-volatile main memory. “So we are challenged to maintain the benefits of Java and the abstraction it provides from hardware while still exploiting the new innovations in hardware,” said McGee.McGee discussed transactional messaging applications where developers send messages transactionally persist a message to storage, something traditionally done by backing messages on spinning disks, something mostly outdated. “Now,” he pointed out, “we would use SSD and store it in Flash and get 70,000 messages a second. If we stored it using a PCI express-based flash memory device, it is still Flash but put on a PCI express bus on a card closer to the CPU. This way I get 300,000 messages a second and 25% improvement in latency.” McGee’s central point was that hardware has a huge impact on the performance and scalability of applications. New technologies are enabling developers to build classes of Java applications previously unheard of. “We need to be able to balance these things in Java – we need to maintain the abstraction but also be able to exploit the evolution of hardware technology,” said McGee. According to McGee, IBM's current focus is on systems wherein hardware and software are shipped together in what are called Expert Integrated Systems – systems that are pre-optimized, and pre-integrated together. McGee closed IBM’s engaging and thought-provoking keynote by pointing out that the use of Java in complex applications is increasingly being augmented by a host of other languages with strong communities around them – JavaScript, JRuby, Scala, Python and so forth. Java developers now must understand the strengths and weaknesses of such newcomers as applications increasingly involve a complex interconnection of languages.

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  • InnoDB Compression Improvements in MySQL 5.6

    - by Inaam Rana
    MySQL 5.6 comes with significant improvements for the compression support inside InnoDB. The enhancements that we'll talk about in this piece are also a good example of community contributions. The work on these was conceived, implemented and contributed by the engineers at Facebook. Before we plunge into the details let us familiarize ourselves with some of the key concepts surrounding InnoDB compression. In InnoDB compressed pages are fixed size. Supported sizes are 1, 2, 4, 8 and 16K. The compressed page size is specified at table creation time. InnoDB uses zlib for compression. InnoDB buffer pool will attempt to cache compressed pages like normal pages. However, whenever a page is actively used by a transaction, we'll always have the uncompressed version of the page as well i.e.: we can have a page in the buffer pool in compressed only form or in a state where we have both the compressed page and uncompressed version but we'll never have a page in uncompressed only form. On-disk we'll always only have the compressed page. When both compressed and uncompressed images are present in the buffer pool they are always kept in sync i.e.: changes are applied to both atomically. Recompression happens when changes are made to the compressed data. In order to minimize recompressions InnoDB maintains a modification log within a compressed page. This is the extra space available in the page after compression and it is used to log modifications to the compressed data thus avoiding recompressions. DELETE (and ROLLBACK of DELETE) and purge can be performed without recompressing the page. This is because the delete-mark bit and the system fields DB_TRX_ID and DB_ROLL_PTR are stored in uncompressed format on the compressed page. A record can be purged by shuffling entries in the compressed page directory. This can also be useful for updates of indexed columns, because UPDATE of a key is mapped to INSERT+DELETE+purge. A compression failure happens when we attempt to recompress a page and it does not fit in the fixed size. In such case, we first try to reorganize the page and attempt to recompress and if that fails as well then we split the page into two and recompress both pages. Now lets talk about the three major improvements that we made in MySQL 5.6.Logging of Compressed Page Images:InnoDB used to log entire compressed data on the page to the redo logs when recompression happens. This was an extra safety measure to guard against the rare case where an attempt is made to do recovery using a different zlib version from the one that was used before the crash. Because recovery is a page level operation in InnoDB we have to be sure that all recompress attempts must succeed without causing a btree page split. However, writing entire compressed data images to the redo log files not only makes the operation heavy duty but can also adversely affect flushing activity. This happens because redo space is used in a circular fashion and when we generate much more than normal redo we fill up the space much more quickly and in order to reuse the redo space we have to flush the corresponding dirty pages from the buffer pool.Starting with MySQL 5.6 a new global configuration parameter innodb_log_compressed_pages. The default value is true which is same as the current behavior. If you are sure that you are not going to attempt to recover from a crash using a different version of zlib then you should set this parameter to false. This is a dynamic parameter.Compression Level:You can now set the compression level that zlib should choose to compress the data. The global parameter is innodb_compression_level - the default value is 6 (the zlib default) and allowed values are 1 to 9. Again the parameter is dynamic i.e.: you can change it on the fly.Dynamic Padding to Reduce Compression Failures:Compression failures are expensive in terms of CPU. We go through the hoops of recompress, failure, reorganize, recompress, failure and finally page split. At the same time, how often we encounter compression failure depends largely on the compressibility of the data. In MySQL 5.6, courtesy of Facebook engineers, we have an adaptive algorithm based on per-index statistics that we gather about compression operations. The idea is that if a certain index/table is experiencing too many compression failures then we should try to pack the 16K uncompressed version of the page less densely i.e.: we let some space in the 16K page go unused in an attempt that the recompression won't end up in a failure. In other words, we dynamically keep adding 'pad' to the 16K page till we get compression failures within an agreeable range. It works the other way as well, that is we'll keep removing the pad if failure rate is fairly low. To tune the padding effort two configuration variables are exposed. innodb_compression_failure_threshold_pct: default 5, range 0 - 100,dynamic, implies the percentage of compress ops to fail before we start using to padding. Value 0 has a special meaning of disabling the padding. innodb_compression_pad_pct_max: default 50, range 0 - 75, dynamic, the  maximum percentage of uncompressed data page that can be reserved as pad.

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  • Swap partition not recognized (The disk drive with UUID=... is not ready yet or not present)

    - by ladaghini
    I think I had an encrypted swap partition, because I chose to encrypt my home directory during the installation. I believe that's what the line with /dev/mapper/cryptswap1 ... in my /etc/fstab is all about. I did something to bork my swap because on the next boot, I got a message (paraphrased): The disk drive for /dev/mapper/cryptswap1 is not ready yet or not present. Wait to continue. Press S to skip or M to manually recover. (As a side note, pressing S or M seemed to do nothing different from just waiting.) Here's what I've tried: This tutorial on how to fix the swap partition not mounting. However, in the above, the mkswap command fails because the device is busy. So I booted from a live USB, ran GParted to reformat the swap partition (which showed up as an unknown fs type), and chrooted into the broken system to try that tutorial again. I also adjusted /etc/initramfs-tools/conf.d/resume and /etc/fstab to reflect the new UUID generated from formatting the partition as a swap. That still didn't work; instead of /dev/mapper/cryptswap1 not present, "The disk drive with UUID=[swap partition's UUID] is not ready yet or not present..." So I decided to start afresh as though I never had created a swap partition in the first place. From the Live USB, I deleted the swap partition altogether (which, again showed up in GParted as an unknown fs type), removed the swap and cryptswap entries in /etc/fstab as well as removed /etc/initramfs-tools/conf.d/resume and /etc/crypttab. At this point the main system shouldn't be considered broken because there is no swap partition and no instructions to mount one, right? I didn't get any errors during startup. I followed the same instructions to create and encrypt the swap partition, starting with creating a partition for the swap, though I think fdisk said a reboot was necessary to see changes. I was confident the 3rd process above would work, but the problem yet persists. Some relevant info (/dev/sda8 is the swap partition): /etc/fstab file: # /etc/fstab: static file system information. # # Use 'blkid' to print the universally unique identifier for a # device; this may be used with UUID= as a more robust way to name devices # that works even if disks are added and removed. See fstab(5). # # <file system> <mount point> <type> <options> <dump> <pass> proc /proc proc nodev,noexec,nosuid 0 0 # / was on /dev/sda6 during installation UUID=4c11e82c-5fe9-49d5-92d9-cdaa6865c991 / ext4 errors=remount-ro 0 1 # /boot was on /dev/sda5 during installation UUID=4031413e-e89f-49a9-b54c-e887286bb15e /boot ext4 defaults 0 2 # /home was on /dev/sda7 during installation UUID=d5bbfc6f-482a-464e-9f26-fd213230ae84 /home ext4 defaults 0 2 # swap was on /dev/sda8 during installation UUID=5da2c720-8787-4332-9317-7d96cf1e9b80 none swap sw 0 0 /dev/mapper/cryptswap1 none swap sw 0 0 output of sudo mount: /dev/sda6 on / type ext4 (rw,errors=remount-ro) proc on /proc type proc (rw,noexec,nosuid,nodev) sysfs on /sys type sysfs (rw,noexec,nosuid,nodev) none on /sys/fs/fuse/connections type fusectl (rw) none on /sys/kernel/debug type debugfs (rw) none on /sys/kernel/security type securityfs (rw) udev on /dev type devtmpfs (rw,mode=0755) devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620) tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755) none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880) none on /run/shm type tmpfs (rw,nosuid,nodev) /dev/sda5 on /boot type ext4 (rw) /dev/sda7 on /home type ext4 (rw) /home/undisclosed/.Private on /home/undisclosed type ecryptfs (ecryptfs_check_dev_ruid,ecryptfs_cipher=aes,ecryptfs_key_bytes=16,ecryptfs_unlink_sigs,ecryptfs_sig=cbae1771abd34009,ecryptfs_fnek_sig=7cefe2f59aab8e58) gvfs-fuse-daemon on /home/undisclosed/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=undisclosed) output of sudo blkid (note that /dev/sda8 is missing): /dev/sda1: LABEL="SYSTEM" UUID="960490E80490CC9D" TYPE="ntfs" /dev/sda2: UUID="D4043140043126C0" TYPE="ntfs" /dev/sda3: LABEL="Shared" UUID="80F613E1F613D5EE" TYPE="ntfs" /dev/sda5: UUID="4031413e-e89f-49a9-b54c-e887286bb15e" TYPE="ext4" /dev/sda6: UUID="4c11e82c-5fe9-49d5-92d9-cdaa6865c991" TYPE="ext4" /dev/sda7: UUID="d5bbfc6f-482a-464e-9f26-fd213230ae84" TYPE="ext4" /dev/mapper/cryptswap1: UUID="41fa147a-3e2c-4e61-b29b-3f240fffbba0" TYPE="swap" output of sudo fdisk -l: Disk /dev/mapper/cryptswap1 doesn't contain a valid partition table Disk /dev/sda: 320.1 GB, 320072933376 bytes 255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xdec3fed2 Device Boot Start End Blocks Id System /dev/sda1 * 2048 409599 203776 7 HPFS/NTFS/exFAT /dev/sda2 409600 210135039 104862720 7 HPFS/NTFS/exFAT /dev/sda3 210135040 415422463 102643712 7 HPFS/NTFS/exFAT /dev/sda4 415424510 625141759 104858625 5 Extended /dev/sda5 415424512 415922175 248832 83 Linux /dev/sda6 415924224 515921919 49998848 83 Linux /dev/sda7 515923968 621389823 52732928 83 Linux /dev/sda8 621391872 625141759 1874944 82 Linux swap / Solaris Disk /dev/mapper/cryptswap1: 1919 MB, 1919942656 bytes 255 heads, 63 sectors/track, 233 cylinders, total 3749888 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xaf5321b5 /etc/initramfs-tools/conf.d/resume file: RESUME=UUID=5da2c720-8787-4332-9317-7d96cf1e9b80 /etc/crypttab file: cryptswap1 /dev/sda8 /dev/urandom swap,cipher=aes-cbc-essiv:sha256 output of sudo swapon -as: Filename Type Size Used Priority /dev/mapper/cryptswap1 partition 1874940 0 -1 output of sudo free -m: total used free shared buffers cached Mem: 1476 1296 179 0 35 671 -/+ buffers/cache: 590 886 Swap: 1830 0 1830 So, how can this be fixed?

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  • Ransomware: Why This New Malware is So Dangerous and How to Protect Yourself

    - by Chris Hoffman
    Ransomware is a type of malware that tries to extort money from you. One of the nastiest examples, CryptoLocker, takes your files hostage and holds them for ransom, forcing you to pay hundreds of dollars to regain access. Most malware is no longer created by bored teenagers looking to cause some chaos. Much of the current malware is now produced by organized crime for profit and is becoming increasingly sophisticated. How Ransomware Works Not all ransomware is identical. The key thing that makes a piece of malware “ransomware” is that it attempts to extort a direct payment from you. Some ransomware may be disguised. It may function as “scareware,” displaying a pop-up that says something like “Your computer is infected, purchase this product to fix the infection” or “Your computer has been used to download illegal files, pay a fine to continue using your computer.” In other situations, ransomware may be more up-front. It may hook deep into your system, displaying a message saying that it will only go away when you pay money to the ransomware’s creators. This type of malware could be bypassed via malware removal tools or just by reinstalling Windows. Unfortunately, Ransomware is becoming more and more sophisticated. One of the latest examples, CryptoLocker, starts encrypting your personal files as soon as it gains access to your system, preventing access to the files without knowing the encryption key. CryptoLocker then displays a message informing you that your files have been locked with encryption and that you have just a few days to pay up. If you pay them $300, they’ll hand you the encryption key and you can recover your files. CryptoLocker helpfully walks you through choosing a payment method and, after paying, the criminals seem to actually give you a key that you can use to restore your files. You can never be sure that the criminals will keep their end of the deal, of course. It’s not a good idea to pay up when you’re extorted by criminals. On the other hand, businesses that lose their only copy of business-critical data may be tempted to take the risk — and it’s hard to blame them. Protecting Your Files From Ransomware This type of malware is another good example of why backups are essential. You should regularly back up files to an external hard drive or a remote file storage server. If all your copies of your files are on your computer, malware that infects your computer could encrypt them all and restrict access — or even delete them entirely. When backing up files, be sure to back up your personal files to a location where they can’t be written to or erased. For example, place them on a removable hard drive or upload them to a remote backup service like CrashPlan that would allow you to revert to previous versions of files. Don’t just store your backups on an internal hard drive or network share you have write access to. The ransomware could encrypt the files on your connected backup drive or on your network share if you have full write access. Frequent backups are also important. You wouldn’t want to lose a week’s worth of work because you only back up your files every week. This is part of the reason why automated back-up solutions are so convenient. If your files do become locked by ransomware and you don’t have the appropriate backups, you can try recovering them with ShadowExplorer. This tool accesses “Shadow Copies,” which Windows uses for System Restore — they will often contain some personal files. How to Avoid Ransomware Aside from using a proper backup strategy, you can avoid ransomware in the same way you avoid other forms of malware. CryptoLocker has been verified to arrive through email attachments, via the Java plug-in, and installed on computers that are part of the Zeus botnet. Use a good antivirus product that will attempt to stop ransomware in its tracks. Antivirus programs are never perfect and you could be infected even if you run one, but it’s an important layer of defense. Avoid running suspicious files. Ransomware can arrive in .exe files attached to emails, from illicit websites containing pirated software, or anywhere else that malware comes from. Be alert and exercise caution over the files you download and run. Keep your software updated. Using an old version of your web browser, operating system, or a browser plugin can allow malware in through open security holes. If you have Java installed, you should probably uninstall it. For more tips, read our list of important security practices you should be following. Ransomware — CryptoLocker in particular — is brutally efficient and smart. It just wants to get down to business and take your money. Holding your files hostage is an effective way to prevent removal by antivirus programs after it’s taken root, but CryptoLocker is much less scary if you have good backups. This sort of malware demonstrates the importance of backups as well as proper security practices. Unfortunately, CryptoLocker is probably a sign of things to come — it’s the kind of malware we’ll likely be seeing more of in the future.     

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  • Not getting desired results with SSAO implementation

    - by user1294203
    After having implemented deferred rendering, I tried my luck with a SSAO implementation using this Tutorial. Unfortunately, I'm not getting anything that looks like SSAO, you can see my result below. You can see there is some weird pattern forming and there is no occlusion shading where there needs to be (i.e. in between the objects and on the ground). The shaders I implemented follow: #VS #version 330 core uniform mat4 invProjMatrix; layout(location = 0) in vec3 in_Position; layout(location = 2) in vec2 in_TexCoord; noperspective out vec2 pass_TexCoord; smooth out vec3 viewRay; void main(void){ pass_TexCoord = in_TexCoord; viewRay = (invProjMatrix * vec4(in_Position, 1.0)).xyz; gl_Position = vec4(in_Position, 1.0); } #FS #version 330 core uniform sampler2D DepthMap; uniform sampler2D NormalMap; uniform sampler2D noise; uniform vec2 projAB; uniform ivec3 noiseScale_kernelSize; uniform vec3 kernel[16]; uniform float RADIUS; uniform mat4 projectionMatrix; noperspective in vec2 pass_TexCoord; smooth in vec3 viewRay; layout(location = 0) out float out_AO; vec3 CalcPosition(void){ float depth = texture(DepthMap, pass_TexCoord).r; float linearDepth = projAB.y / (depth - projAB.x); vec3 ray = normalize(viewRay); ray = ray / ray.z; return linearDepth * ray; } mat3 CalcRMatrix(vec3 normal, vec2 texcoord){ ivec2 noiseScale = noiseScale_kernelSize.xy; vec3 rvec = texture(noise, texcoord * noiseScale).xyz; vec3 tangent = normalize(rvec - normal * dot(rvec, normal)); vec3 bitangent = cross(normal, tangent); return mat3(tangent, bitangent, normal); } void main(void){ vec2 TexCoord = pass_TexCoord; vec3 Position = CalcPosition(); vec3 Normal = normalize(texture(NormalMap, TexCoord).xyz); mat3 RotationMatrix = CalcRMatrix(Normal, TexCoord); int kernelSize = noiseScale_kernelSize.z; float occlusion = 0.0; for(int i = 0; i < kernelSize; i++){ // Get sample position vec3 sample = RotationMatrix * kernel[i]; sample = sample * RADIUS + Position; // Project and bias sample position to get its texture coordinates vec4 offset = projectionMatrix * vec4(sample, 1.0); offset.xy /= offset.w; offset.xy = offset.xy * 0.5 + 0.5; // Get sample depth float sample_depth = texture(DepthMap, offset.xy).r; float linearDepth = projAB.y / (sample_depth - projAB.x); if(abs(Position.z - linearDepth ) < RADIUS){ occlusion += (linearDepth <= sample.z) ? 1.0 : 0.0; } } out_AO = 1.0 - (occlusion / kernelSize); } I draw a full screen quad and pass Depth and Normal textures. Normals are in RGBA16F with the alpha channel reserved for the AO factor in the blur pass. I store depth in a non linear Depth buffer (32F) and recover the linear depth using: float linearDepth = projAB.y / (depth - projAB.x); where projAB.y is calculated as: and projAB.x as: These are derived from the glm::perspective(gluperspective) matrix. z_n and z_f are the near and far clip distance. As described in the link I posted on the top, the method creates samples in a hemisphere with higher distribution close to the center. It then uses random vectors from a texture to rotate the hemisphere randomly around the Z direction and finally orients it along the normal at the given pixel. Since the result is noisy, a blur pass follows the SSAO pass. Anyway, my position reconstruction doesn't seem to be wrong since I also tried doing the same but with the position passed from a texture instead of being reconstructed. I also tried playing with the Radius, noise texture size and number of samples and with different kinds of texture formats, with no luck. For some reason when changing the Radius, nothing changes. Does anyone have any suggestions? What could be going wrong?

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  • How Can I Safely Destroy Sensitive Data CDs/DVDs?

    - by Jason Fitzpatrick
    You have a pile of DVDs with sensitive information on them and you need to safely and effectively dispose of them so no data recovery is possible. What’s the most safe and efficient way to get the job done? Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-driven grouping of Q&A web sites. The Question SuperUser reader HaLaBi wants to know how he can safely destroy CDs and DVDs with personal data on them: I have old CDs/DVDs which have some backups, these backups have some work and personal files. I always had problems when I needed to physically destroy them to make sure no one will reuse them. Breaking them is dangerous, pieces could fly fast and may cause harm. Scratching them badly is what I always do but it takes long time and I managed to read some of the data in the scratched CDs/DVDs. What’s the way to physically destroy a CD/DVD safely? How should he approach the problem? The Answer SuperUser contributor Journeyman Geek offers a practical solution coupled with a slightly mad-scientist solution: The proper way is to get yourself a shredder that also handles cds – look online for cd shredders. This is the right option if you end up doing this routinely. I don’t do this very often – For small scale destruction I favour a pair of tin snips – they have enough force to cut through a cd, yet are blunt enough to cause small cracks along the sheer line. Kitchen shears with one serrated side work well too. You want to damage the data layer along with shearing along the plastic, and these work magnificently. Do it in a bag, cause this generates sparkly bits. There’s also the fun, and probably dangerous way – find yourself an old microwave, and microwave them. I would suggest doing this in a well ventilated area of course, and not using your mother’s good microwave. There’s a lot of videos of this on YouTube – such as this (who’s done this in a kitchen… and using his mom’s microwave). This results in a very much destroyed cd in every respect. If I was an evil hacker mastermind, this is what I’d do. The other options are better for the rest of us. Another contributor, Keltari, notes that the only safe (and DoD approved) way to dispose of data is total destruction: The answer by Journeyman Geek is good enough for almost everything. But oddly, that common phrase “Good enough for government work” does not apply – depending on which part of the government. It is technically possible to recover data from shredded/broken/etc CDs and DVDs. If you have a microscope handy, put the disc in it and you can see the pits. The disc can be reassembled and the data can be reconstructed — minus the data that was physically destroyed. So why not just pulverize the disc into dust? Or burn it to a crisp? While technically, that would completely eliminate the data, it leaves no record of the disc having existed. And in some places, like DoD and other secure facilities, the data needs to be destroyed, but the disc needs to exist. If there is a security audit, the disc can be pulled to show it has been destroyed. So how can a disc exist, yet be destroyed? Well, the most common method is grinding the disc down to destroy the data, yet keep the label surface of the disc intact. Basically, it’s no different than using sandpaper on the writable side, till the data is gone. Have something to add to the explanation? Sound off in the the comments. Want to read more answers from other tech-savvy Stack Exchange users? Check out the full discussion thread here.     

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  • CPU Usage in Very Large Coherence Clusters

    - by jpurdy
    When sizing Coherence installations, one of the complicating factors is that these installations (by their very nature) tend to be application-specific, with some being large, memory-intensive caches, with others acting as I/O-intensive transaction-processing platforms, and still others performing CPU-intensive calculations across the data grid. Regardless of the primary resource requirements, Coherence sizing calculations are inherently empirical, in that there are so many permutations that a simple spreadsheet approach to sizing is rarely optimal (though it can provide a good starting estimate). So we typically recommend measuring actual resource usage (primarily CPU cycles, network bandwidth and memory) at a given load, and then extrapolating from those measurements. Of course there may be multiple types of load, and these may have varying degrees of correlation -- for example, an increased request rate may drive up the number of objects "pinned" in memory at any point, but the increase may be less than linear if those objects are naturally shared by concurrent requests. But for most reasonably-designed applications, a linear resource model will be reasonably accurate for most levels of scale. However, at extreme scale, sizing becomes a bit more complicated as certain cluster management operations -- while very infrequent -- become increasingly critical. This is because certain operations do not naturally tend to scale out. In a small cluster, sizing is primarily driven by the request rate, required cache size, or other application-driven metrics. In larger clusters (e.g. those with hundreds of cluster members), certain infrastructure tasks become intensive, in particular those related to members joining and leaving the cluster, such as introducing new cluster members to the rest of the cluster, or publishing the location of partitions during rebalancing. These tasks have a strong tendency to require all updates to be routed via a single member for the sake of cluster stability and data integrity. Fortunately that member is dynamically assigned in Coherence, so it is not a single point of failure, but it may still become a single point of bottleneck (until the cluster finishes its reconfiguration, at which point this member will have a similar load to the rest of the members). The most common cause of scaling issues in large clusters is disabling multicast (by configuring well-known addresses, aka WKA). This obviously impacts network usage, but it also has a large impact on CPU usage, primarily since the senior member must directly communicate certain messages with every other cluster member, and this communication requires significant CPU time. In particular, the need to notify the rest of the cluster about membership changes and corresponding partition reassignments adds stress to the senior member. Given that portions of the network stack may tend to be single-threaded (both in Coherence and the underlying OS), this may be even more problematic on servers with poor single-threaded performance. As a result of this, some extremely large clusters may be configured with a smaller number of partitions than ideal. This results in the size of each partition being increased. When a cache server fails, the other servers will use their fractional backups to recover the state of that server (and take over responsibility for their backed-up portion of that state). The finest granularity of this recovery is a single partition, and the single service thread can not accept new requests during this recovery. Ordinarily, recovery is practically instantaneous (it is roughly equivalent to the time required to iterate over a set of backup backing map entries and move them to the primary backing map in the same JVM). But certain factors can increase this duration drastically (to several seconds): large partitions, sufficiently slow single-threaded CPU performance, many or expensive indexes to rebuild, etc. The solution of course is to mitigate each of those factors but in many cases this may be challenging. Larger clusters also lead to the temptation to place more load on the available hardware resources, spreading CPU resources thin. As an example, while we've long been aware of how garbage collection can cause significant pauses, it usually isn't viewed as a major consumer of CPU (in terms of overall system throughput). Typically, the use of a concurrent collector allows greater responsiveness by minimizing pause times, at the cost of reducing system throughput. However, at a recent engagement, we were forced to turn off the concurrent collector and use a traditional parallel "stop the world" collector to reduce CPU usage to an acceptable level. In summary, there are some less obvious factors that may result in excessive CPU consumption in a larger cluster, so it is even more critical to test at full scale, even though allocating sufficient hardware may often be much more difficult for these large clusters.

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  • High Availability for IaaS, PaaS and SaaS in the Cloud

    - by BuckWoody
    Outages, natural disasters and unforeseen events have proved that even in a distributed architecture, you need to plan for High Availability (HA). In this entry I'll explain a few considerations for HA within Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS) and Software-as-a-Service (SaaS). In a separate post I'll talk more about Disaster Recovery (DR), since each paradigm has a different way to handle that. Planning for HA in IaaS IaaS involves Virtual Machines - so in effect, an HA strategy here takes on many of the same characteristics as it would on-premises. The primary difference is that the vendor controls the hardware, so you need to verify what they do for things like local redundancy and so on from the hardware perspective. As far as what you can control and plan for, the primary factors fall into three areas: multiple instances, geographical dispersion and task-switching. In almost every cloud vendor I've studied, to ensure your application will be protected by any level of HA, you need to have at least two of the Instances (VM's) running. This makes sense, but you might assume that the vendor just takes care of that for you - they don't. If a single VM goes down (for whatever reason) then the access to it is lost. Depending on multiple factors, you might be able to recover the data, but you should assume that you can't. You should keep a sync to another location (perhaps the vendor's storage system in another geographic datacenter or to a local location) to ensure you can continue to serve your clients. You'll also need to host the same VM's in another geographical location. Everything from a vendor outage to a network path problem could prevent your users from reaching the system, so you need to have multiple locations to handle this. This means that you'll have to figure out how to manage state between the geo's. If the system goes down in the middle of a transaction, you need to figure out what part of the process the system was in, and then re-create or transfer that state to the second set of systems. If you didn't write the software yourself, this is non-trivial. You'll also need a manual or automatic process to detect the failure and re-route the traffic to your secondary location. You could flip a DNS entry (if your application can tolerate that) or invoke another process to alias the first system to the second, such as load-balancing and so on. There are many options, but all of them involve coding the state into the application layer. If you've simply moved a state-ful application to VM's, you may not be able to easily implement an HA solution. Planning for HA in PaaS Implementing HA in PaaS is a bit simpler, since it's built on the concept of stateless applications deployment. Once again, you need at least two copies of each element in the solution (web roles, worker roles, etc.) to remain available in a single datacenter. Also, you need to deploy the application again in a separate geo, but the advantage here is that you could work out a "shared storage" model such that state is auto-balanced across the world. In fact, you don't have to maintain a "DR" site, the alternate location can be live and serving clients, and only take on extra load if the other site is not available. In Windows Azure, you can use the Traffic Manager service top route the requests as a type of auto balancer. Even with these benefits, I recommend a second backup of storage in another geographic location. Storage is inexpensive; and that second copy can be used for not only HA but DR. Planning for HA in SaaS In Software-as-a-Service (such as Office 365, or Hadoop in Windows Azure) You have far less control over the HA solution, although you still maintain the responsibility to ensure you have it. Since each SaaS is different, check with the vendor on the solution for HA - and make sure you understand what they do and what you are responsible for. They may have no HA for that solution, or pin it to a particular geo, or perhaps they have a massive HA built in with automatic load balancing (which is often the case).   All of these options (with the exception of SaaS) involve higher costs for the design. Do not sacrifice reliability for cost - that will always cost you more in the end. Build in the redundancy and HA at the very outset of the project - if you try to tack it on later in the process the business will push back and potentially not implement HA. References: http://www.bing.com/search?q=windows+azure+High+Availability  (each type of implementation is different, so I'm routing you to a search on the topic - look for the "Patterns and Practices" results for the area in Azure you're interested in)

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  • GRUB is not Booting Correctly

    - by msknapp
    I have a PC with three hard disks. Windows 7 is installed on the first, Ubuntu 14.04 is installed on the third. After I re-booted, it went straight to Windows 7. So I tried explicitly telling my PC to boot using the third hard disk, but that just takes me to the grub rescue prompt. I followed Scott Severence's instructions here to try and recover. Essentially, I updated grub, reinstalled grub, and then updated it again. After re-booting, absolutely nothing had changed. So instead I tried using the boot-repair tool. In the past it had failed for me, saying that I had programs running and it could not unmount drives, when I was running nothing. I never figured out how to solve that problem, but it went away when I bought another hard drive and used that for my Ubuntu installation, I don't know why. In any case, I ran the boot-repair tool and this time it said it was successful. First time for everything right? I re-booted, only to be taken straight to the grub rescue prompt. So I changed my BIOS settings to use the third hard disk for boot start up. That is the same hard drive where I have Ubuntu and grub installed, and the same one that the grub-repair tool told me to use. It still took me straight to the grub rescue prompt. So I went from not being able to boot Ubuntu, to not being able to boot either OS installed on my system. Thanks boot-repair! Boot repair gave me this URL for future troubleshooting: http://paste.ubuntu.com/8131669 When I try to boot from the third hard disk, this is my console: Loading Operating System ... error: attempt to read or write outside of disk 'hd0'. Entering rescue mode... grub rescue> grub rescue> set cmdpath=(hd0) prefix=(hd0,gpt2)/boot/grub root=hd0,gpt2 grub rescue> ls (hd0) (hd0,gpt3) (hd0,gpt2) (hd0,gpt1) (hd1) (hd2) (hd2,gpt2) (hd2,gpt1) (hd3) Those values look correct to me. I have also experimented with changing some of those values, but 'insmod normal' always throws the same error. Somebody please tell me how to fix this. I have tried everything, reinstalling grub, and running boot-repair. =========================== Update: I think the problem might be that the ubuntu installer did not partition my hard disk correctly. I booted from live USB and then launched gparted and looked at how it partitioned things. This is what gparted says: Partition, File System, Size, Used, Unused, Flags /dev/sda1 (!), unknown, 1.00 MiB, ---, ---, bios_grub /dev/sda2, ext4, 2.71 TiB, 47.30 GiB, 2.67 TiB, /dev/sda3, linux-swap, 16.00 GiB, 0.00 B, 16.00 GiB, So that first line looks problematic. It is supposed to be the /boot partition. However, it was given only 1 MiB? I am assuming that MiB is actually supposed to mean megabyte, no idea why that 'i' is there. It also says the file system is unknown. I read the answer by andrew here, and he says he had to do a custom install, explicitly configuring the boot partition. So I think that maybe Ubuntu's installer has a bug in it, where it does not set up the boot partition correctly if you are not installing on the first hard disk in your computer. I am going to try reinstalling with a custom partition scheme. I read elsewhere (askubuntu won't let me post another link) that I don't even need a /boot partition any more. So instead of following Andrew's instructions ver batim, I'm first going to try having just two partitions: one for /, and another for my 16GB swap space. Both as primary partitions. The first will be formatted as ext4. If that doesn't work, I may try again using /boot. ======================== So I did my custom install with no /boot partition, and it did not work. When I rebooted, I had an error message saying that some address did not exist. So for the hundredth time, I booted from the live USB, and ran boot-repair. Now I get this message GPT detected. Please create a BIOS-Boot partition (>1MB, unformatted filesystem, bios_grub flag). This can be performed via tools such as Gparted. Then try again. I feel like I'm running in circles and nobody will help me.

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  • Spring JMS MQJE001: Completion Code '2', Reason '2042'.

    - by john
    My setup is Spring 3 JMS, MVC + Websphere MQ + Websphere 7 <!-- this is the Message Driven POJO (MDP) --> <bean id="messageListener" class="com.SomeListener" /> <!-- and this is the message listener container --> <bean id="jmsContainer" class="org.springframework.jms.listener.DefaultMessageListenerContainer"> <property name="connectionFactory" ref="xxxCF" /> <property name="destination" ref="someQueue" /> <property name="messageListener" ref="messageListener" /> </bean> When I start up the server, the listener seems to start correctly since it receives the messages that are on the queue as I put them. However, once I run any simple controller/action that doesn't even have anything to do with JMS it gives me the message below over and over... DefaultMessag W org.springframework.jms.listener.DefaultMessageListenerContainer handleListenerSetupFailure Setup of JMS message listener invoker failed for destination 'queue:///ABCDEF.EFF.OUT?persistence=-1' - trying to recover. Cause: MQJMS2008: failed to open MQ queue ''.; nested exception is com.ibm.mq.MQException: MQJE001: Completion Code '2', Reason '2042'. DefaultMessag I org.springframework.jms.listener.DefaultMessageListenerContainer refreshConnectionUntilSuccessful Successfully refreshed JMS Connection ConnectionEve W J2CA0206W: A connection error occurred. To help determine the problem, enable the Diagnose Connection Usage option on the Connection Factory or Data Source. ConnectionEve A J2CA0056I: The Connection Manager received a fatal connection error from the Resource Adapter for resource JMS$XXXQCF$JMSManagedConnection@2. The exception is: javax.jms.JMSException: MQJMS2008: failed to open MQ queue ''. ConnectionEve W J2CA0206W: A connection error occurred. To help determine the problem, enable the Diagnose Connection Usage option on the Connection Factory or Data Source. ConnectionEve A J2CA0056I: The Connection Manager received a fatal connection error from the Resource Adapter for resource jms/XXXQCF. The exception is: javax.jms.JMSException: MQJMS2008: failed to open MQ queue ''. The original listener seems to be still running correctly...but I think the controller is somehow triggering off another connection? Does anyone know what I should check for or what might cause this issue? thanks

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  • Portable C Compiler (pcc) with GTK+ in Code::Blocks

    - by CMPITG
    I had some problems when trying to compile a GTK+ program with Portable C Compiler (pcc) using Code::Blocks in Windows. When I tried to build the default GTK+ project in Code::Blocks, I get these errors: -------------- Build: Debug in cb-temp2 --------------- Compiling: main.c C:\CMPITG\gtk\include\glib-2.0/glib/gutils.h, line 423: parameter 'glib_major_version' not defined C:\CMPITG\gtk\include\glib-2.0/glib/gutils.h, line 424: function declaration in bad context C:\CMPITG\gtk\include\glib-2.0/glib/gutils.h, line 424: parameter '__declspec' not defined C:\CMPITG\gtk\include\glib-2.0/glib/gutils.h, line 424: parse error C:\CMPITG\gtk\include\glib-2.0/glib/gutils.h, line 425: redeclaration of __declspec C:\CMPITG\gtk\include\glib-2.0/glib/gutils.h, line 425: parameter 'glib_micro_version' not defined C:\CMPITG\gtk\include\glib-2.0/glib/gutils.h, line 426: function declaration in bad context C:\CMPITG\gtk\include\glib-2.0/glib/gutils.h, line 426: parameter '__declspec' not defined C:\CMPITG\gtk\include\glib-2.0/glib/gutils.h, line 426: parse error C:\CMPITG\gtk\include\glib-2.0/glib/gutils.h, line 427: redeclaration of __declspec C:\CMPITG\gtk\include\glib-2.0/glib/gutils.h, line 427: parameter 'glib_binary_age' not defined C:\CMPITG\gtk\include\glib-2.0/glib/gutils.h, line 431: parameter 'glib_check_version' not defined C:\CMPITG\gtk\include\glib-2.0/glib/gatomic.h, line 42: parameter 'g_atomic_int_exchange_and_add' not defined C:\CMPITG\gtk\include\glib-2.0/glib/gatomic.h, line 44: parameter 'g_atomic_int_add' not defined C:\CMPITG\gtk\include\glib-2.0/glib/gatomic.h, line 47: parameter 'g_atomic_int_compare_and_exchange' not defined C:\CMPITG\gtk\include\glib-2.0/glib/gatomic.h, line 50: parameter 'g_atomic_pointer_compare_and_exchange' not defined C:\CMPITG\gtk\include\glib-2.0/glib/gatomic.h, line 52: parameter 'g_atomic_int_get' not defined C:\CMPITG\gtk\include\glib-2.0/glib/gatomic.h, line 54: parameter 'g_atomic_int_set' not defined C:\CMPITG\gtk\include\glib-2.0/glib/gatomic.h, line 55: parameter 'g_atomic_pointer_get' not defined C:\CMPITG\gtk\include\glib-2.0/glib/gatomic.h, line 57: parameter 'g_atomic_pointer_set' not defined C:\CMPITG\gtk\include\glib-2.0/glib/gthread.h, line 44: parameter 'g_thread_error_quark' not defined C:\CMPITG\gtk\include\glib-2.0/glib/gthread.h, line 50: parameter 'GThreadError' not defined C:\CMPITG\gtk\include\glib-2.0/glib/gthread.h, line 52: parameter 'GThreadFunc' not defined C:\CMPITG\gtk\include\glib-2.0/glib/gthread.h, line 60: parameter 'GThreadPriority' not defined C:\CMPITG\gtk\include\glib-2.0/glib/gthread.h, line 62: parameter 'GThread' not defined C:\CMPITG\gtk\include\glib-2.0/glib/gthread.h, line 66: parse error C:\CMPITG\gtk\include\glib-2.0/glib/gthread.h, line 66: invalid function definition C:\CMPITG\gtk\include\glib-2.0/glib/gthread.h, line 66: function illegal in structure or union C:\CMPITG\gtk\include\glib-2.0/glib/gthread.h, line 66: invalid function definition C:\CMPITG\gtk\include\glib-2.0/glib/gthread.h, line 66: function illegal in structure or union C:\CMPITG\gtk\include\glib-2.0/glib/gthread.h, line 67: cannot recover from earlier errors: goodbye! Process terminated with status 1 (0 minutes, 1 seconds) 0 errors, 0 warnings I have successfully compiled the same project with gcc and now I'm still not able to compile it with pcc. Does anyone know how to solve it?

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  • ! Extra }, or forgotten \endgroup. latex

    - by gzou
    hey, I met these latex format problem, anyone can offer some help? the .tex file: \begin{table}{} \renewcommand{\arraystretch}{1.1} \caption{Cambridge Flow feature definition and description} \label{cambridge-feature}} \centering \begin{tabular}{|c|c|} \hline\bfseries Abbreviation &\bfseries Description\\ \hline serv-port & Server port\\ \hline clnt-port & Client port\\ \hline push-pkts-serv & count of all packets with\\ & push bit set in TCP header (server to client)\\ \hline init-win-bytes-clnt & the total number of bytes \\ & sent in initial window (client to server)\\ \hline init-win-bytes-serv & the total number of bytes sent\\ & in initial window (server to client)\\ \hline avg-seg-size-clnt & average segment size: \\ & data bytes devided by number of packets\\ \hline IP-bytes-med-clnt & median of total bytes in IP packet\\ \hline act-data-pkt-serv & count of packet with at least one byte \\ & of TCP data playload (server to client)\\ \hline data-bytes-var-clnt & variance of total \\ & bytes in packets (client to server)\\ \hline min-seg-size-serv & minimum segment size \\ & observed (server to client)\\ \hline RTT-samples-serv & total number of RTT samples\\ & found (server to client),\\ & {\bf see also \cite{Moore05discriminators}}\\ \hline push-pkts-clnt & count of all packets with push bit set \\ & in TCP header (server to client)\\ \hline \end{tabular} \end{table} and the error message: ! Extra }, or forgotten \endgroup. \@endfloatbox ...pagefalse \outer@nobreak \egroup \color@endbox l.892 \end{table} I've deleted a group-closing symbol because it seems to be spurious, as in $x}$'. But perhaps the } is legitimate and you forgot something else, as in\hbox{$x}'. In such cases the way to recover is to insert both the forgotten and the deleted material, e.g., by typing `I$}'. there is no $ in my table, also this { are matching with the }, and also after I comment the citation, the error remains. anyone can offer help? really appreciate all the comments! ! Extra }, or forgotten \endgroup.

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  • Mac OS - Built SVN from source, now Apache2 not loading sites

    - by Geuis
    This relates to another question I asked earlier today. I built SVN 1.6.2 from source. In the process, it has completely screwed up my dev environment. After I built SVN, Apache wasn't loading. It was giving me this error: Syntax error on line 117 of /private/etc/apache2/httpd.conf: Cannot load /usr/libexec /apache2/mod_dav_svn.so into server: dlopen(/usr/libexec/apache2/mod_dav_svn.so, 10): no suitable image found. Did find:\n\t/usr/libexec/apache2/mod_dav_svn.so: mach-o, but wrong architecture It appears that SVN over-wrote the old mod_dav_svn.so and I am not able to get it to build as FAT, and I can't recover whatever was originally there. I resolved this(temporarily?) by commenting out the line that was loading the mod_dav_svn.so and got Apache to start at this point. However, even though Apache is running I am now getting this error when trying to access my dev sites: Directory index forbidden by Options directive: /usr/share/tomcat6/webapps/ROOT/ I have Apache2 sitting in front of Tomcat6. I access my local dev site using the internal name "http://localthesite". I have had virtual directories set up that have worked until this SVN debacle. Tomcat is installed at /usr/local/apache-tomcat, and webapps is /usr/local/apache-tomcat/webapps. Our production servers deploy tomcat to /usr/share/tomcat6, so I have symlinks setup on my system to replicate this as well. These point back to the actual installation path. This has all been working fine as well. None of our configurations for Apache2, Tomcat, or .htaccess have changed. Over the weekend, I performed a "Repair Disk Permissions" on the system. This was before I discovered the mod_dav_svn.so problem. I have been reading up on this all morning and the most common answer is that there is an Options -Indexes set. We have this in a config file, but it was there before and when I removed it during testing, I still got the same errors from Apache. At this point, I'm assuming I either totally borked the native Apache2 installation on this Mac, or that there is a permissions error somewhere that I'm missing. The permissions error could be from the SVN installation, or from my repair process. Does anyone have any idea what could be the problem? I'm totally blocked right now and have no idea where to check next.

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  • github like workflow on private server over ssh

    - by Jesse
    I have an server (available via ssh) on the internet that my friend and I use for working on projects together. We have started using git for source control. Our setup currently is as follows: Friend created repository on server with git init named project.friend.git I cloned project.friend.git on server to project.jesse.git I then cloned project.jesse.git on server to my local machine using git clone jesse@server:/git_repos/project.jesse.git I work on my local machine and commit to the local machine. When I want to push my changes to the project.jesse.git on server I use git push origin master. My friend is working on project.friend.git. When I want to get his changes I do pull jesse@server:/git_repos/project.friend.git. Everything seems to be working fine, however, I am now getting the following error when I do git push origin master: localpc:project.jesse jesse$ git push origin master Counting objects: 100, done. Delta compression using up to 2 threads. Compressing objects: 100% (76/76), done. Writing objects: 100% (76/76), 15.98 KiB, done. Total 76 (delta 50), reused 0 (delta 0) warning: updating the current branch warning: Updating the currently checked out branch may cause confusion, warning: as the index and work tree do not reflect changes that are in HEAD. warning: As a result, you may see the changes you just pushed into it warning: reverted when you run 'git diff' over there, and you may want warning: to run 'git reset --hard' before starting to work to recover. warning: warning: You can set 'receive.denyCurrentBranch' configuration variable to warning: 'refuse' in the remote repository to forbid pushing into its warning: current branch. warning: To allow pushing into the current branch, you can set it to 'ignore'; warning: but this is not recommended unless you arranged to update its work warning: tree to match what you pushed in some other way. warning: warning: To squelch this message, you can set it to 'warn'. warning: warning: Note that the default will change in a future version of git warning: to refuse updating the current branch unless you have the warning: configuration variable set to either 'ignore' or 'warn'. To jesse@server:/git_repos/project.jesse.git c455cb7..e9ec677 master -> master Is this warning anything I need to be worried about? Like I said, everything seems to be working. My friend is able to pull my changes in from my branch. I have the clone on the server so he can access it since he does not have access to my local machine. Is there something that could be done better? Thanks!

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