Search Results

Search found 1451 results on 59 pages for 'theory'.

Page 51/59 | < Previous Page | 47 48 49 50 51 52 53 54 55 56 57 58  | Next Page >

• Migrate from Oracle to MySQL

  - by Cassy

  Hi together. We ran into serious performance problems with our Oracle database and we would like to try to migrate to a MySQL-based database (either MySQL directly or, more preferrable, Infobright). The thing is, we need to let the old and the new system overlap for at least some weeks if not months, before we actually know, if all features of the new database match our needs. So, here is our situation: The Oracle database consists of multiple tables with each millions of rows. During the day, there are literally thousands of statements, which we cannot stop for migration. Every morning, new data is imported into the Oracle database, replacing some thousands of rows. Copying this process is not a problem, so we could, in theory, import in both databases in parallel. But, and here lies the challenge, for this to work, we need to have an export from the Oracle database with a consistent state from one day. (We cannot export some tables on Monday and some others on Tuesday, etc.) This means, that at least the export should be finished in less than one day. Our first thought was to dump the schema, but I wasn't able to find a tool to import an Oracle dump file into mysql. Exporting tables in CSV files might work, but I'm afraid it could take too long. So my question now is: What should I do? Is there any tool to import Oracle dump files into MySQL? Does anybody have any experience with such a large-scale migration? Thanks in advance, Cassy PS: Please, don't suggest performance optimization techniques for Oracle, we already tried a lot :-)

  Read the article

• Setting up a transparent SSL proxy

  - by badunk

  I've got a linux box set up with 2 network cards to inspect traffic going through port 80. One card is used to go out to the internet, the other one is hooked up to a networking switch. The point is to be able to inspect all HTTP and HTTPS traffic on devices hooked up to that switch for debugging purposes. I've written the following rules for iptables: nat -A PREROUTING -i eth1 -p tcp -m tcp --dport 80 -j DNAT --to-destination 192.168.2.1:1337 -A PREROUTING -i eth1 -p tcp -m tcp --dport 80 -j REDIRECT --to-ports 1337 -A POSTROUTING -s 192.168.2.0/24 -o eth0 -j MASQUERADE On 192.168.2.1:1337, I've got a transparent http proxy using Charles (http://www.charlesproxy.com/) for recording. Everything's fine for port 80, but when I add similar rules for port 443 (SSL) pointing to port 1337, I get an error about invalid message through Charles. I've used SSL proxying on the same computer before with Charles (http://www.charlesproxy.com/documentation/proxying/ssl-proxying/), but have been unsuccessful with doing it transparently for some reason. Some resources I've googled say its not possible - I'm willing to accept that as an answer if someone can explain why. As a note, I have full access to the described set up including all the clients hooked up to the subnet - so I can accept self-signed certs by Charles. The solution doesn't have to be Charles-specific since in theory, any transparent proxy will do. Thanks! Edit: After playing with it a little, I was able to get it working for a specific host. When I modify my iptables to the following (and open 1338 in charles for reverse proxy): nat -A PREROUTING -i eth1 -p tcp -m tcp --dport 80 -j DNAT --to-destination 192.168.2.1:1337 -A PREROUTING -i eth1 -p tcp -m tcp --dport 80 -j REDIRECT --to-ports 1337 -A PREROUTING -i eth1 -p tcp -m tcp --dport 443 -j DNAT --to-destination 192.168.2.1:1338 -A PREROUTING -i eth1 -p tcp -m tcp --dport 443 -j REDIRECT --to-ports 1338 -A POSTROUTING -s 192.168.2.0/24 -o eth0 -j MASQUERADE I am able to get a response, but with no destination host. In the reverse proxy, if I just specify that everything from 1338 goes to a specific host that I wanted to hit, it performs the hand shake properly and I can turn on SSL proxying to inspect the communication. The setup is less than ideal because I don't want to assume everything from 1338 goes to that host - any idea why the destination host is being stripped? Thanks again

  Read the article

• multiple webapps in tomcat -- what is the optimal architecture?

  - by rvdb

  I am maintaining a growing base of mainly Cocoon-2.1-based web applications [http://cocoon.apache.org/2.1/], deployed in a Tomcat servlet container [http://tomcat.apache.org/], and proxied with an Apache http server [http://httpd.apache.org/docs/2.2/]. I am conceptually struggling with the best way to deploy multiple web applications in Tomcat. Since I'm not a Java programmer and we don't have any sysadmin staff I have to figure out myself what is the most sensible way to do this. My setup has evolved through 2 scenarios and I'm considering a third for maximal separation of the distinct webapps. [1] 1 Tomcat instance, 1 Cocoon instance, multiple webapps -tomcat |_ webapps |_ webapp1 |_ webapp2 |_ webapp[n] |_ WEB-INF (with Cocoon libs) This was my first approach: just drop all web applications inside a single Cocoon webapps folder inside a single Tomcat container. This seemed to run fine, I did not encounter any memory issues. However, this poses a maintainability drawback, as some Cocoon components are subject to updates, which often affect the webapp coding. Hence, updating Cocoon becomes unwieldy: since all webapps share the same pool of Cocoon components, updating one of them would require the code in all web applications to be updated simultaneously. In order to isolate the web applications, I moved to the second scenario. [2] 1 Tomcat instance, each webapp in its dedicated Cocoon environment -tomcat |_ webapps |_ webapp1 | |_ WEB-INF (with Cocoon libs) |_ webapp1 | |_ WEB-INF (with Cocoon libs) |_ webapp[n] |_ WEB-INF (with Cocoon libs) This approach separates all webapps into their own Cocoon environment, run inside a single Tomcat container. In theory, this works fine: all webapps can be updated independently. However, this soon results in PermGenSpace errors. It seemed that I could manage the problem by increasing memory allocation for Tomcat, but I realise this isn't a structural solution, and that overloading a single Tomcat in this way is prone to future memory errors. This set me thinking about the third scenario. [3] multiple Tomcat instances, each with a single webapp in its dedicated Cocoon environment -tomcat |_ webapps |_ webapp1 |_ WEB-INF (with Cocoon libs) -tomcat |_ webapps |_ webapp2 |_ WEB-INF (with Cocoon libs) -tomcat |_ webapps |_ webapp[n] |_ WEB-INF (with Cocoon libs) I haven't tried this approach, but am thinking of the $CATALINA_BASE variable. A single Tomcat distribution can be multiply instanciated with different $CATALINA_BASE environments, each pointing to a Cocoon instance with its own webapp. I wonder whether such an approach could avoid the structural memory-related problems of approach [2], or will the same issues apply? On the other hand, this approach would complicate management of the Apache http frontend, as it will require the AJP connectors of the different Tomcat instances to be listening at different ports. Hence, Apache's worker configuration has to be updated and reloaded whenever a new webapp (in its own Tomcat instance) is added. And there seems no way to reload worker.properties without restarting the entire Apache http server. Is there perhaps another / more dynamic way of 'modularizing' multiple Tomcat-served webapps, or can one of these scenarios be refined? Any thoughts, suggestions, advice much appreciated. Ron

  Read the article

• order of operations for environment variables

  - by alyda

  I want to understand how environment variables are set and reset (overridden). I'm running Apache/2.2.24 (Unix) PHP/5.4.14 on a mac . My theory is this: Environment vars can be set in bash, then they can be overwritten with httpd.conf preceding a VirtualHost directive that precedes php.ini, which can then be overwritten by .htaccess (if allowable) and finally by PHP I tried the following: setting environment variable in bash: I added export ENVIRONMENT='local' to my ~/.bashrc file, restarted apache and did not get any output from print_r($_ENV); (in a simple index.php file at the root of my webserver). I also tried putting ENVIRONMENT='local' into /etc/environment, and restarting apache, nothing, as well as /etc/bashrc, restart apache. still nothing. setting environment variable in httpd.conf: I added SetEnv ENVIRONMENT 'local-httpd to the end of my /etc/apache2/httpd.conf file (but before I load other conf files, such as virtual host [Include /private/etc/apache2/other/*.conf]). I now see the variable in the array print_r($_SERVER); but not print_r($_ENV);. setting environment variable in httpd-vhosts.conf: I added SetEnv ENVIRONMENT 'local-vhost to my /etc/apache2/extra/httpd-vhosts.conf file in my generic directive that points to my default document root. I now see the variable has been overwritten (to local-vhost from local-httpd, so I know where the variable is getting set). setting environment variable in php.ini: while searching for a proper place to put my environment variable, I noticed that variables_order = "GPCS" was set to the production value rather than EGPCS. I changed it, restarted my server and found that I was now getting output for print_r($_ENV); but not my expected custom variable. It also appears that I am not able to set a custom variable in this file. Please tell me if I am wrong setting environment variable in .htaccess: I added SetEnv ENVIRONMENT 'local-htaccess'. This worked as expected, overwriting all other values that were set. setting / overwriting environment variable in PHP: if (...) { putenv('ENVIRONMENT=local'); } I'm asking this question because I have a lot of local and remote testing servers, some of which may or may not allow me access to modify httpd, httpd-vhost, php.ini or environment variables. I want to understand what is best for those difference scenarios (shared hosting, heroku, local servers, etc) I obviously don't know how to properly set the environment variable in bash in a way that php can use it, I'd like to know how to do that (as I think Heroku does something similar with heroku config set...)

  Read the article

• How to grow to be global sysadmin of an organization?

  - by user64729

  Bit of a non-technical question but I have seen questions of the career development type on here before so hopefully it is fine. I work for a fast growing but still small organization (~65 employees). I have been their external sysadmin for a while now, looking after hosted Linux servers and infrastructure. In the past 12 months I have been transforming into the internal sysadmin for our office too. I'm currently studying Cisco CCNA to cover the demands of being an internal sysadmin and looking after the office LAN, routers, switches and VPNs. Now they want me to look after the global sysadmin function of the organization as a whole. The organization has 3 offices in total, 2 in the UK and 1 in the US. I work in one of the UK offices. The other offices are primarily Windows desktops with AD domain shops. My office is primarily a Linux shop with a file-server and NFS/NIS (no AD domain for the Windows desktops yet but it's in the works). Each other office has a sysadmin which in theory I am supposed to supervise but in reality each is independent. I have a very competent junior sysadmin working with me who shares the day-to-day tasks and does some of the longer term projects with my supervision. My boss has asked me how to grow from being the external sysadmin to the global sysadmin. I am to ponder this and then report back to him on how to achieve this. My current thoughts are: Management training or professional development - eg. reading books such as "Influencer" and "7 Habits". Also I feel I should take steps to improving communication skills since a senior person is expected to talk and speak out more often. Learn more about Windows and Active Directory - I'm an LPI-certified guy and have a lot of experience in Linux (Ubuntu or desktop, Debian/Ubuntu as server). Since the other offices are mainly Windows-domains it makes sense to skill-up in that area so I can understand what the other admins are talking about. Talk to previous colleagues who have are are in this role already - to try and get the benefit of their experience. Produce an "IT Roadmap" or similar that maps out where we want the organization to be and when, plotted out over the next couple of years with regards to internal and external infrastructure. I have produced a "Security roadmap" already which does cover some of these things. I guess this can summed up as "thinking more strategically"? I'd appreciate comments from anyone who has been through a similar situation, thanks.

  Read the article

• SAS Expanders vs Direct Attached (SAS)?

  - by jemmille

  I have a storage unit with 2 backplanes. One backplane holds 24 disks, one backplane holds 12 disks. Each backplane is independently connected to a SFF-8087 port (4 channel/12Gbit) to the raid card. Here is where my question really comes in. Can or how easily can a backplane be overloaded? All the disks in the machine are WD RE4 WD1003FBYX (black) drives that have average writes at 115MB/sec and average read of 125 MB/sec I know things would vary based on the raid or filesystem we put on top of that but it seems to be that a 24 disk backplane with only one SFF-8087 connector should be able to overload the bus to a point that might actually slow it down? Based on my math, if I had a RAID0 across all 24 disks and asked for a large file, I should, in theory should get 24*115 MB/sec wich translates to 22.08 GBit/sec of total throughput. Either I'm confused or this backplane is horribly designed, at least in a perfomance environment. I'm looking at switching to a model where each drive has it's own channel from the backplane (and new HBA's or raid card). EDIT: more details We have used both pure linux (centos), open solaris, software raid, hardware raid, EXT3/4, ZFS. Here are some examples using bonnie++ 4 Disk RAID-0, ZFS WRITE CPU RE-WRITE CPU READ CPU RND-SEEKS 194MB/s 19% 92MB/s 11% 200MB/s 8% 310/sec 194MB/s 19% 93MB/s 11% 201MB/s 8% 312/sec --------- ---- --------- ---- --------- ---- --------- 389MB/s 19% 186MB/s 11% 402MB/s 8% 311/sec 8 Disk RAID-0, ZFS WRITE CPU RE-WRITE CPU READ CPU RND-SEEKS 324MB/s 32% 164MB/s 19% 346MB/s 13% 466/sec 324MB/s 32% 164MB/s 19% 348MB/s 14% 465/sec --------- ---- --------- ---- --------- ---- --------- 648MB/s 32% 328MB/s 19% 694MB/s 13% 465/sec 12 Disk RAID-0, ZFS WRITE CPU RE-WRITE CPU READ CPU RND-SEEKS 377MB/s 38% 191MB/s 22% 429MB/s 17% 537/sec 376MB/s 38% 191MB/s 22% 427MB/s 17% 546/sec --------- ---- --------- ---- --------- ---- --------- 753MB/s 38% 382MB/s 22% 857MB/s 17% 541/sec Now 16 Disk RAID-0, it's gets interesting WRITE CPU RE-WRITE CPU READ CPU RND-SEEKS 359MB/s 34% 186MB/s 22% 407MB/s 18% 1397/sec 358MB/s 33% 186MB/s 22% 407MB/s 18% 1340/sec --------- ---- --------- ---- --------- ---- --------- 717MB/s 33% 373MB/s 22% 814MB/s 18% 1368/sec 20 Disk RAID-0, ZFS WRITE CPU RE-WRITE CPU READ CPU RND-SEEKS 371MB/s 37% 188MB/s 22% 450MB/s 19% 775/sec 370MB/s 37% 188MB/s 22% 447MB/s 19% 797/sec --------- ---- --------- ---- --------- ---- --------- 741MB/s 37% 376MB/s 22% 898MB/s 19% 786/sec 24 Disk RAID-1, ZFS WRITE CPU RE-WRITE CPU READ CPU RND-SEEKS 347MB/s 34% 193MB/s 22% 447MB/s 19% 907/sec 347MB/s 34% 192MB/s 23% 446MB/s 19% 933/sec --------- ---- --------- ---- --------- ---- --------- 694MB/s 34% 386MB/s 22% 894MB/s 19% 920/sec 28 Disk RAID-0, ZFS 32 Disk RAID-0, ZFS 36 Disk RAID-0, ZFS More details: Here is the exact unit: http://www.supermicro.com/products/chassis/4U/847/SC847E1-R1400U.cfm

  Read the article

• Preinstalled Windows 8 and Linux UEFI dual boot on a laptop

  - by itchy355

  I am trying to set up Windows 8 and Arch Linux on a new Sony Vaio E14 with preinstalled windows 8. So far: installed W8 to my new SSD (switched for the original HDD) using Recovery Media shrunk the W8 partition, deleted recovery partition, disabled swap confirmed W8 booting just fine On to Arch: disabled Secure Boot in bios confirmed W8 booting just fine Booted Arch off the CD and installed everything to 4th and 5th partition set up rEFInd for EFIstub kernel bootloader After that it got worse. I was unable to boot anything else than Windows 8 (although I was glad that they at least kept working just fine). Tried: creating EFI\refind\ and putting the .efi there (as per Arch manual overwriting EFI\boot\bootx64.efi overwriting EFI\Microsoft\Boot\bootmgr.efi overwriting EFI\Microsoft\Boot\bootmgfw.efi --- YAY rEFInd shown up! So far, so good. I've kept the whole W8 Boot\ directory in EFI\windows8 and set up a boot menuentry for it; and it booted just fine. But, upon restart, everything was wrong -- 'Operating system not found' instead of any bootloader (refind or w8). Booted back into Arch using the live CD to find out that the EFI partition had erroneous FAT table. fsck.vfat fixed it, and I've found that EFI\Microsoft\Boot was back to it's original state (all refind files deleted and replaced with W8 bootloaders). I've overwritten them again and got back to rEFInd showing up correctly and Arch being perfectly bootable. After that I've tried only renaming EFI\Microsoft\Boot\bootmgfw.efi to bootmgfw.001.efi (then copying refind's .efi to bootmgfw.efi and keeping EVERY OTHER file as it was), but with exactly the same result. Tried marking the GPT EFI partition as read-only, same result. Now I'm kinda out of luck. Arch boots fine, so does W8 but it destroys the EFI partition in the process. Thanks for any ideas, Googling brought me this far and I can't find any better. PS -- windows 8 MAYBE destroys the partition upon shutdown -- when I order a shutdown in W8, it takes unusually long (about half a minute instead of ~5 seconds). So in theory I could solve this by hard-resetting the laptop instead of a normal shutdown, but that's just not nice.

  Read the article

• Ubuntu Lucid: Erratic screen behaviour after boot

  - by fgysin

  In short: about 50% of the time I have a screwed up monitor setup after reboot. About 50% it is totally correct. Now the longer version: I updated my machine from 9.04 to 10.04 (via 9.10). At first I run into some monitor problems (I have a 3-monitor setup) because of the known bug in the new xserver driver for xinerama. This messes up behaviour if the mouse goes either left or above the screen number 0, i.e. I had to make my left-most monitor screen 0. Everything worked out fine finally, I got my 3-monitor setup back with xinerama enabled to get one big desktop streched over 3 screens. Now the fun part: Every time I start up my machine only one of the 3 monitors gets a signal and is woken up: it only recognizes the left-most monitor (screen 0) and crams all the desktop stuff into this one screen. If I go into nvidia settings I only see one physical device although all 3 are connected and have power. When I look into the xorg.conf I can still see my old setup with 3 devices, 3 screens, xinerama active etc... But I was totally unable to get 3 montitors to work. (I tried unplugging monitors, reconfiguring whole nvidia setup, ...) But it gets even better: When I restart my machine (i.e. choose the restart option from the Ubuntu menu) it shuts down and tries to restart. The restart then gets stuck after showing the Ubuntu splash screen with the 'loading bar' (the moving dots thingy) and I am forced to kill the machine by cutting power. But after the power cut the machine boots up normally and suddenly I get my 3 monitor setup back up working. That is until the next time I shut down and start up, where it all starts over again and I only have one monitor... (see above) I really have a hard time seeing where the error is. It must be that the restart boot somehow differs from the 'normal' boot. But the fact that it gets stuck and I need to cut power which then basically triggers a 'normal' boot does not really support this theory... My setup (please tell me if you need further info): 3 monitors as 3 screens as one desktop (with xinerama) 2 nvidia cards where screen 0 and 1 are on card 0 and screen 2 is on card 1 Ubuntu 10.04 Lucid Lynx (updated from 9.10, 9.04, ....) I would appreciate every idea on the subject, at the moment I really don't have any clue what to do...

  Read the article

• Tracking down rogue disk usage

  - by Amadan

  I found several other questions regarding the theory behind my problem (e.g. this, this), but I don't know how to apply the answers to my machine. # du -hsx / 11000283 / # df -kT / Filesystem Type 1K-blocks Used Available Use% Mounted on /dev/mapper/csisv13-root ext4 516032952 361387456 128432532 74% / There is a big difference between 11G (du) and 345G (df). Where are the remaining 334G? It's not in deleted files. There was only one, it was short, and I truncated it just in case. This is what remains: # lsof -a +L1 / COMMAND PID USER FD TYPE DEVICE SIZE/OFF NLINK NODE NAME zabbix_ag 4902 zabbix 1w REG 252,0 0 0 28836028 /var/log/zabbix-agent/zabbix_agentd.log.1 (deleted) zabbix_ag 4902 zabbix 2w REG 252,0 0 0 28836028 /var/log/zabbix-agent/zabbix_agentd.log.1 (deleted) zabbix_ag 4906 zabbix 1w REG 252,0 0 0 28836028 /var/log/zabbix-agent/zabbix_agentd.log.1 (deleted) zabbix_ag 4906 zabbix 2w REG 252,0 0 0 28836028 /var/log/zabbix-agent/zabbix_agentd.log.1 (deleted) zabbix_ag 4907 zabbix 1w REG 252,0 0 0 28836028 /var/log/zabbix-agent/zabbix_agentd.log.1 (deleted) zabbix_ag 4907 zabbix 2w REG 252,0 0 0 28836028 /var/log/zabbix-agent/zabbix_agentd.log.1 (deleted) zabbix_ag 4908 zabbix 1w REG 252,0 0 0 28836028 /var/log/zabbix-agent/zabbix_agentd.log.1 (deleted) zabbix_ag 4908 zabbix 2w REG 252,0 0 0 28836028 /var/log/zabbix-agent/zabbix_agentd.log.1 (deleted) zabbix_ag 4909 zabbix 1w REG 252,0 0 0 28836028 /var/log/zabbix-agent/zabbix_agentd.log.1 (deleted) zabbix_ag 4909 zabbix 2w REG 252,0 0 0 28836028 /var/log/zabbix-agent/zabbix_agentd.log.1 (deleted) zabbix_ag 4910 zabbix 1w REG 252,0 0 0 28836028 /var/log/zabbix-agent/zabbix_agentd.log.1 (deleted) zabbix_ag 4910 zabbix 2w REG 252,0 0 0 28836028 /var/log/zabbix-agent/zabbix_agentd.log.1 (deleted) I rebooted to see if fsck does anything. But, from /var/log/boot.log, it seems there are no issues: /dev/mapper/server-root: clean, 3936097/32768000 files, 125368568/131064832 blocks Thinking maybe someone overzealously reserved root space, I checked the master record: # tune2fs -l /dev/mapper/server-root tune2fs 1.42 (29-Nov-2011) Filesystem volume name: <none> Last mounted on: / Filesystem UUID: 86430ade-cea7-46ce-979c-41769a41ecbe Filesystem magic number: 0xEF53 Filesystem revision #: 1 (dynamic) Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize Filesystem flags: signed_directory_hash Default mount options: user_xattr acl Filesystem state: clean Errors behavior: Continue Filesystem OS type: Linux Inode count: 32768000 Block count: 131064832 Reserved block count: 6553241 Free blocks: 5696264 Free inodes: 28831903 First block: 0 Block size: 4096 Fragment size: 4096 Reserved GDT blocks: 992 Blocks per group: 32768 Fragments per group: 32768 Inodes per group: 8192 Inode blocks per group: 512 Flex block group size: 16 Filesystem created: Fri Feb 1 13:44:04 2013 Last mount time: Tue Aug 19 16:56:13 2014 Last write time: Fri Feb 1 13:51:28 2013 Mount count: 9 Maximum mount count: -1 Last checked: Fri Feb 1 13:44:04 2013 Check interval: 0 (<none>) Lifetime writes: 1215 GB Reserved blocks uid: 0 (user root) Reserved blocks gid: 0 (group root) First inode: 11 Inode size: 256 Required extra isize: 28 Desired extra isize: 28 Journal inode: 8 First orphan inode: 28836028 Default directory hash: half_md4 Directory Hash Seed: bca55ff5-f530-48d1-8347-25c004f66d43 Journal backup: inode blocks The system is: # uname -a Linux server 3.2.0-67-generic #101-Ubuntu SMP Tue Jul 15 17:46:11 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux # cat /etc/lsb-release DISTRIB_ID=Ubuntu DISTRIB_RELEASE=12.04 DISTRIB_CODENAME=precise DISTRIB_DESCRIPTION="Ubuntu 12.04.2 LTS" Does anyone have any tips on what exactly to do to find and hopefully reclaim the missing space?

  Read the article

• Fedora 13 post security update boot problem

  - by Alex

  Hello. About a month ago I installed a security update that had new Kernek 2.6.34.x from 2.6.33.x), this is when the problem occurred for the first time. After the install my computer would not boot at all, black screen without any visible hard drive activity (I gave it good 30 minutes on black screen, before took actions)... I poped in installation DVD and went in rescue mode to change back the boot option to old kernel (was just a guess where the problem was). After restart computer loaded just file, took a long time for it to start because of SELinux targeted policy relabel is required. Relabeling could take very long time depending on file size. I assumed that the update got messed up somehow and continued working with modified boot option. Couple of days ago, there was another kernel update. I installed it and same problem as before. This rules out corrupted update theory... Black screen right after 'BIOS' screen before OS gets loaded. I had to rescue system again... Below is copy of my grub.conf file. I am fairly new to LINUX (couple of years of experience), mostly development and basic config... nothing crazy. # grub.conf generated by anaconda # # Note that you do not have to rerun grub after making changes to this file # NOTICE: You have a /boot partition. This means that # all kernel and initrd paths are relative to /boot/, eg. # root (hd0,0) # kernel /vmlinuz-version ro root=/dev/mapper/vg_obalyuk-lv_root # initrd /initrd-[generic-]version.img #boot=/dev/sda default=2 timeout=0 splashimage=(hd0,0)/grub/splash.xpm.gz hiddenmenu title Fedora (2.6.34.6-54.fc13.i686.PAE) root (hd0,0) kernel /vmlinuz-2.6.34.6-54.fc13.i686.PAE ro root=/dev/mapper/vg_obalyuk-lv_root rd_LVM_LV=vg_obalyuk/lv_root rd_LVM_LV=vg_obalyuk/lv_swap rd_NO_LUKS rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYTABLE=us rhgb quiet initrd /initramfs-2.6.34.6-54.fc13.i686.PAE.img title Fedora (2.6.34.6-47.fc13.i686.PAE) root (hd0,0) kernel /vmlinuz-2.6.34.6-47.fc13.i686.PAE ro root=/dev/mapper/vg_obalyuk-lv_root rd_LVM_LV=vg_obalyuk/lv_root rd_LVM_LV=vg_obalyuk/lv_swap rd_NO_LUKS rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYTABLE=us rhgb quiet initrd /initramfs-2.6.34.6-47.fc13.i686.PAE.img title Fedora (2.6.33.8-149.fc13.i686.PAE) root (hd0,0) kernel /vmlinuz-2.6.33.8-149.fc13.i686.PAE ro root=/dev/mapper/vg_obalyuk-lv_root rd_LVM_LV=vg_obalyuk/lv_root rd_LVM_LV=vg_obalyuk/lv_swap rd_NO_LUKS rd_NO_MD rd_NO_DM LANG=en_US.UTF-8 SYSFONT=latarcyrheb-sun16 KEYTABLE=us rhgb quiet initrd /initramfs-2.6.33.8-149.fc13.i686.PAE.img I like my system to be up to date... Let me know if I can post any other files that can be of help. Has anyone else had this problem? Does anyone has any ideas how to fix this problem? p.s. Anything helps, you ppl are great! thx for ur time.

  Read the article

• Windows XP machine not seeing external FAT32 partitions correctly

  - by Rob_before_edits

  About 8 months ago my Windows XP machine stopped being able to see FAT32 external drives when I plug them in... mostly. I will explain... It happens with all my FAT32 drives, whether they be unpowered external hard drives, powered external hard drives, SDHC cards plugged directly into the machine's card reader, or SDHC cards plugged in via a separate USB card reader. All of these drives/cards used to work fine on this machine. They all stopped working at about the same time. NTFS volumes are not affected. If I plug in NTFS external drives they are recognized right away. I even have one external drive with two partitions on it, one is NTFS which is recognized, the other is FAT32, which is not recognized. If I attach a FAT32 drive, then reboot, then the drive almost always becomes visible to the machine after the reboot. Sometimes I can plug in a FAT32 drive and it works right away. Not often though. I'd say I get lucky more often with SDHC cards than hard drives. I'm developing a theory that I only get lucky with hard drives if I'm running Acronis Disk Director when I plug them in, though that usually doesn't work either - I need more data here, this may be a red herring. Getting lucky with a hard drive is really rare, usually I have to reboot. When a FAT32 is recognized, either because I got lucky or because I rebooted, I can almost never safely disconnect it. It tells me "The device 'Generic volume' cannot be stopped right now. Try stopping the device again later". I can't seem to get around this. IIRC, I've tried closing every open window, and still no luck. Since I care about my data usually the only way to disconnect a FAT32 drive is to shut down the machine. As you can imagine, two reboots just to read a drive is getting pretty old... When the machine fails to see a FAT32 drive it usually comes up with the appropriate drive letter and the words "Local Disk" in Windows Explorer instead of the correct partition name. If I click on it I get "J:\ is not accessible. The parameter is incorrect." Before this problem arose I always clicked the "safely remove" button for everything, including SDHC cards where I think it's not necessary. I've known for a long time that this is the correct procedure for hard drives, so I don't think failing to do this was the cause of this problem (before someone asks :) Any answers or suggestions most welcome.

  Read the article

• Email delivery management grievances

  - by joxl

  The question I have may be more of principle than anything else, but here's my dilemma. I manage an email system for a small company (about 20 email users). We own a plain-letter .com domain name through Network Solutions. Our email service is hosted by Google Apps. Recently (Feb. 2011) we've been having customers report that they aren't getting our emails. Upon further investigation it seems that the failed emails are all to a common (well known) domain. We have not received any bounce messages for the emails. We've also contacted a few of the intended recipients, who have reported that the messages are not in their spam box; they simply did not receive anything. In these cases we re-sent the same email to an alternate address on another domain, which was successful received. One customer contacted their email provider about the issue. The provider recommended that we submit a form to be white-listed by their domain. Here's where my problem begins. I feel like this is heading down a slippery slope. Doesn't this undermine the very principle of email? If this is the appropriate action to take in these situations where will it end? In theory (following this model) it could be argued that eventually one will first need to "whitelist" (or more appropriately termed "authenticate") themselves with an email host before actually sending any messages. More to this point, what keeps the "bad" spammers from doing the same thing...? We've just gone full circle. I know avoiding anti-spam measures is a big cat-and-mouse game, but I think this is the wrong way of "patching" the problem. Email standards say that messages should not just disappear silently. I have a problem supporting a model that says "you must do < this to make sure your emails aren't ignored". I have a notion to call the provider and voice my complaint, although I have a feeling it will probably fall on deaf ears. Am I missing something here? Is this an acceptable approach to email spam problems? What should I do?

  Read the article

• Crashes and freezes after fixing "BOOTMGR is missing" error

  - by Greg-J

  I came back from a 3-day weekend to a computer that was off. I leave my PC on 24/7, so this was odd. Turn it on to get the dreaded "BOOTMGR is missing" screen. Two attempts at Windows Recovery and it booted into Windows fine. After an hour or so, I get a frozen Chrome and my start bar disappears. Ctrl+Alt+Del brings up an error box telling me that Ctrl+Alt+Del failed to work properly. Clicking on any open application triggers an error (I can't recall the error now, but it essentially just said that the application couldn't be found running or something along those lines). I restart, and again, the same thing happens after a while of use. I turn it on, install the 47 updates I have or so, and then restart it. After a while of use (under an hour), it just freezes completely. My thoughts are: SSDs, RAM or PS. My system specs below: (RAID0) 2 x Crucial M4 CT128M4SSD2 2.5" 128GB SATA III MLC Internal Solid State Drive (SSD) CORSAIR Vengeance 16GB (4 x 4GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model CML16GX3M4A1600C9 CORSAIR HX Series HX750 750W ATX12V 2.3 / EPS12V 2.91 SLI Ready CrossFire Ready 80 PLUS GOLD Certified Modular Active 1 x ASUS Maximus IV Gene-Z/GEN3 LGA 1155 Intel Z68 HDMI SATA 6Gb/s USB 3.0 Micro ATX Intel Motherboard 1 x Hitachi GST Deskstar 7K1000.C 0F10383 1TB 7200 RPM SATA 3.0Gb/s 3.5" Internal Hard Drive -Bare Drive 1 x Intel Core i7-2600K Sandy Bridge 3.4GHz (3.8GHz Turbo Boost) LGA 1155 95W Quad-Core Desktop Processor Intel HD Graphics 1 x SAPPHIRE 21197-00-40G Radeon HD 7970 3GB 384-bit GDDR5 PCI Express 3.0 x16 HDCP Ready CrossFireX Support Video Card 1 x Noctua NH-D14 120mm & 140mm SSO CPU Cooler This is all crammed in a pretty small case (NZXT Vulcan) and has been running perfectly problem-free since January. The only thing out of the ordinary is that there is a fan in the case that is now making noise whereas the case has previously been completely silent. I have no reason to believe this is anything more then correlation, but felt it is worth mentioning. I believe it MAY be the SSDs simply because of the BOOTMGR error, but not sure how to test that theory. My belief that it may be the RAM is simply from experience with frozen machines. I haven't had the time to memtest it, but will. The PS being the culprit is something I've picked up by reading similar threads on various forums, and it seems plausible. I am unsure how to test this though. ANY insight whatsover would be greatly appreciated!

  Read the article

• Do RAID controllers commonly have SATA drive brand compatibility issues?

  - by Jeff Atwood

  We've struggled with the RAID controller in our database server, a Lenovo ThinkServer RD120. It is a rebranded Adaptec that Lenovo / IBM dubs the ServeRAID 8k. We have patched this ServeRAID 8k up to the very latest and greatest: RAID bios version RAID backplane bios version Windows Server 2008 driver This RAID controller has had multiple critical BIOS updates even in the short 4 month time we've owned it, and the change history is just.. well, scary. We've tried both write-back and write-through strategies on the logical RAID drives. We still get intermittent I/O errors under heavy disk activity. They are not common, but serious when they happen, as they cause SQL Server 2008 I/O timeouts and sometimes failure of SQL connection pools. We were at the end of our rope troubleshooting this problem. Short of hardcore stuff like replacing the entire server, or replacing the RAID hardware, we were getting desperate. When I first got the server, I had a problem where drive bay #6 wasn't recognized. Switching out hard drives to a different brand, strangely, fixed this -- and updating the RAID BIOS (for the first of many times) fixed it permanently, so I was able to use the original "incompatible" drive in bay 6. On a hunch, I began to assume that the Western Digital SATA hard drives I chose were somehow incompatible with the ServeRAID 8k controller. Buying 6 new hard drives was one of the cheaper options on the table, so I went for 6 Hitachi (aka IBM, aka Lenovo) hard drives under the theory that an IBM/Lenovo RAID controller is more likely to work with the drives it's typically sold with. Looks like that hunch paid off -- we've been through three of our heaviest load days (mon,tue,wed) without a single I/O error of any kind. Prior to this we regularly had at least one I/O "event" in this time frame. It sure looks like switching brands of hard drive has fixed our intermittent RAID I/O problems! While I understand that IBM/Lenovo probably tests their RAID controller exclusively with their own brand of hard drives, I'm disturbed that a RAID controller would have such subtle I/O problems with particular brands of hard drives. So my question is, is this sort of SATA drive incompatibility common with RAID controllers? Are there some brands of drives that work better than others, or are "validated" against particular RAID controller? I had sort of assumed that all commodity SATA hard drives were alike and would work reasonably well in any given RAID controller (of sufficient quality).

  Read the article

• Ubuntu Lucid: Erratic screen behaviour after boot

  - by fgysin

  In short: about 50% of the time I have a screwed up monitor setup after reboot. About 50% it is totally correct. Now the longer version: I updated my machine from 9.04 to 10.04 (via 9.10). At first I run into some monitor problems (I have a 3-monitor setup) because of the known bug in the new xserver driver for xinerama. This messes up behaviour if the mouse goes either left or above the screen number 0, i.e. I had to make my left-most monitor screen 0. Everything worked out fine finally, I got my 3-monitor setup back with xinerama enabled to get one big desktop streched over 3 screens. Now the fun part: Every time I start up my machine only one of the 3 monitors gets a signal and is woken up: it only recognizes the left-most monitor (screen 0) and crams all the desktop stuff into this one screen. If I go into nvidia settings I only see one physical device although all 3 are connected and have power. When I look into the xorg.conf I can still see my old setup with 3 devices, 3 screens, xinerama active etc... But I was totally unable to get 3 montitors to work. (I tried unplugging monitors, reconfiguring whole nvidia setup, ...) But it gets even better: When I restart my machine (i.e. choose the restart option from the Ubuntu menu) it shuts down and tries to restart. The restart then gets stuck after showing the Ubuntu splash screen with the 'loading bar' (the moving dots thingy) and I am forced to kill the machine by cutting power. But after the power cut the machine boots up normally and suddenly I get my 3 monitor setup back up working. That is until the next time I shut down and start up, where it all starts over again and I only have one monitor... (see above) I really have a hard time seeing where the error is. It must be that the restart boot somehow differs from the 'normal' boot. But the fact that it gets stuck and I need to cut power which then basically triggers a 'normal' boot does not really support this theory... My setup (please tell me if you need further info): 3 monitors as 3 screens as one desktop (with xinerama) 2 nvidia cards where screen 0 and 1 are on card 0 and screen 2 is on card 1 Ubuntu 10.04 Lucid Lynx (updated from 9.10, 9.04, ....) I would appreciate every idea on the subject, at the moment I really don't have any clue what to do...

  Read the article

• SQL Clustering on Hyper V - is a cluster within a cluster a benefit.

  - by Chris W

  This is a re-hash of a question I asked a while back - after a consultant has come in firing ideas in to other teams in the department the whole issue has been raised again hence I'm looking for more detailed answers. We're intending to set-up a multi-instance SQL Cluster across a number of physical blades which will run a variety of different systems across each SQL instance. In general use there will be one virtual SQL instance running on each VM host. Again, in general operation each VM host will run on a dedicated underlying blade. The set-up should give us lots of flexibility for maintenance of any individual VM or underlying blade with all the SQL instances able to fail over as required. My original plan had been to do the following: Install 2008 R2 on each blade Add Hyper V to each blade Install a 2008 R2 VM to each blade Within the VMs - create a failover cluster and then install SQL Server clustering. The consultant has suggested that we instead do the following: Install 2008 R2 on each blade Add Hyper V to each blade Install a 2008 R2 VM to each blade Create a cluster on the HOST machines which will host all the VMs. Within the VMs - create a failover cluster and then install SQL Server clustering. The big difference is the addition of step 4 whereby we cluster all of the guest VMs as well. The argument is that it improves maintenance further since we have no ties at all between the SQL cluster and physical hardware. We can in theory live migrate the guest VMs around the hosts without affecting the SQL cluster at all so we for routine maintenance physical blades we move the SQL cluster around without interruption and without needing to failover. It sounds like a nice idea but I've not come across anything on the internet where people say they've done this and it works OK. Can I actually do the live migrations of the guests without the SQL Cluster hosted within them getting upset? Does anyone have any experience of this set up, good or bad? Are there some pros and cons that I've not considered? I appreciate that mirroring is also a valuable option to consider - in this case we're favouring clustering since it will do the whole of each instance and we have a good number of databases. Some DBs are for lumbering 3rd party systems that may not even work kindly with mirroring (and my understanding of clustering is that fail overs are completely transparent to the clients). Thanks.

  Read the article

• When upgrading from Vista to Windows 7 on a DELL laptop, how do I know which drivers to reinstall an

  - by msorens

  According to Dell's upgrade page for Vista to Windows 7, after using the upgrade assistant the final step is to install drivers. They refer to this page for the order of driver installation, listing 9 items. From there I go to the Dell Drivers and Downloads page, enter my system tag, and get a list of the downloads available for my specific box. That page, by the way, has a link to driver install instructions that lists 10 rather than 9 items. Going to Drivers Help in the side panel and clicking on "In what order should drivers be installed?" shows yet a third list, this one containing 13 items. Not surprisingly, the order of these 3 lists of drivers are not quite the same for the common items! Furthermore, of the 26 files Dell's site recommends for my machine, there are several not shown on any of the 3 lists! I can make determinations for some of these: 6 of them are "applications" so I know which of those I want and that they could probably be safely installed after all drivers. BIOS: I would think this should be unaffected by an OS upgrade so could be skipped. Two tools in the diagnostics category: could probably be done after all drivers. That leaves just a CD/DVD driver and a webcam driver unaccounted for. So my two related questions are these: How critical is the driver installation order and which one do I follow? (Keep in mind this is for an upgrade, not a fresh install.) Where in the order do I insert the CD/DVD and the webcam drivers (if needed) ? Dell's driver download page provides (in theory) the list of all downloads relevant to my specific machine, via the service tag. But do I actually need to reinstall all of them? some? none? How does one determine this? They do label each with Recommended or Optional, so do I need to reinstall all the recommended ones? (Part of the reason for my perplexed frown is that I wonder why I would need to reinstall a CD/DVD driver since I would already be using the drive to install the OS!)

  Read the article

• Why won't IE let users login to a website unless in In Private mode?

  - by Richard Fawcett

  I'm not entirely sure this belongs on SuperUser.com. I also considered ServerFault.com and StackOverflow.com, but on balance, I think it should belong here? We host a website which has the same code responding to multiple domain names. On 28th December (without any changes deployed to the website) a percentage of users suddenly could not login, and the blank login page was just rendered again even when the correct credentials were entered. The issue is still ongoing. After remote controlling an affected user's PC, we've found the following: The issue affects Internet Explorer 9. The user can login from the same machine on Chrome. The user can login from an In Private browser session using IE9. The user can login if the website is added to the Trusted Sites security zone. The user can NOT login from an IE session in safe mode (started with iexplore -extoff). Only one hostname that the website responds to prevents login, the same user account on the other hostname works fine (note that this is identical code and database running server side), even though that site is not in trusted sites zone. Series of HTTP requests in the failure case: GET request to protected page, returns a 302 FOUND response to login page. GET request to login page. POST to login page, containing credentials, returns redirect to protected page. GET request to protected page... for some reason auth fails and browser is redirected to login page, as in step 1. Other information: Operating system is Windows 7 Ultimate Edition. AV system is AVG Internet Security 2012. I can think of lots of things that could be going wrong, but in every case, one of the findings above is incompatible with the theory. Any ideas what is causing login to fail? Update 06-Jan-2012 Enhanced logging has shown that the .ASPXAUTH cookie is being set in step 3. Its expiry date is 28 days in the future, its path is /, the domain is mysite.com, and its value is an encrypted forms ticket, as expected. However, the cookie is not being received by the web server during step 4. Other cookies are being presented to the server during step 4, it's just this one that is missing. I've seen that cookies are usually set with a domain starting with a period, but mine isn't. Should it be .mysite.com instead of mysite.com? However, if this was wrong, it would presumably affect all users?

  Read the article

• System won't boot: Gigabyte HD 7790 1GB OC GPU issue or Corsair VS550 PSU issue?

  - by MGOwen

  Installed a new GPU, and PC won't boot. Turn it on and: No monitor signal at all (tried HDMI and VGA via DVI, on 2 working monitors). CPU and GPU fans DO spin, but No system beeps, no sounds from drives (they might make a small noise in the first 1 second or so, but there's definitely no OS loading or anything like that) If hit "power off" button it turns off immediately (no holding down for 3 seconds like usual) If I put my old HD 5670 GPU back in, everything works fine. But (plot twist!) card is not totally dead. My friend put it in his PC, and it works fine (he even played a game for 15 minutes, no issues). He has a Corsair TX850 850W and a Gigabyte MB. So my main theory is: the GPU isn't getting enough power from the PSU. But is it: Bad PSU? Seems unlikely, since it works fine with the other GPU. Also, the PSU Is brand new and 550W (single 42A/504W 12V rail). Overkill for this GPU. Corsair is a decent brand, but maybe just mine is faulty? Bad GPU? Could it be drawing more power than it should be, somehow, or something? Supposedly HD 7790 needs only 21A/75W on the 12v rail, though this one is factory overclocked a bit... but should that triple the power requirement? Something else? Could there be a motherboard incompatibility somehow? Both MB and GPU are less than a year old and PCI Express 3.0 x16. Things I've tried: Re-seating the video card Testing PC with old GPU (works fine, same PCIe slot). Checked AMD's stated amp/watt requirements of a 7790 and my PSU (see above). My PSU can output twice the amps (single rail) and 5x the Wattage a 7790 needs. Here are the full specs: Gigabyte HD 7790 1GB OC GPU Corsair VS550 550W PSU 4GB RAM AsRock H61M U3S3 motherboard i3-2100 500GB SATA HDD (2007-ish) blu-ray drive (new) PCI 802.11g card Edit: Motherboard BIOS Update seems to have fixed it. (If anyone has same problem and it doesn't work, comment here).

  Read the article

• SanjayP&rsquo;s venture after Microsoft involves no Microsoft

  - by eddraper

  When I was at Microsoft, I always found Sanjay Parthasarathy to be a bright and passionate leader.  While he was a bit disconnected at times with what was really going on out in the trenches, I always thought he was true believer in what we in Developer Platform and Evangelism (DPE) were doing.  He got it.  He had started DPE and kicked a lot of doors down up in Redmond to make it happen.  Back in the early 2000s, battles over platform choices at large customers was trench warfare… bayonets and hand grenades at the P-Code level.  This model was not at all suited to Microsoft’s org structure at the time.  While there were plenty of people fully able to have competitive conversations around Windows Server, or AD, or Exchange, or the desktop, there weren’t many that could have deep technical conversations around Java vs .NET and the platform “stack” as a cohesive, unified unit of value.  This task fell to DPE. Sanjay ended up leaving Microsoft a number of months before me in 2009 and I remember thinking these exact words: “holy shit, SanjayP left Microsoft.”  When SanjayP left DPE years before that,  Sheila Gulati had stepped into his shoes and I thought we where starting to miss a beat.  Sheila had built an amazing business at Microsoft India, but I don’t recall being inspired by her as a leader.  SanjayP’s talks felt like the opening scene of “Patton” with George C. Scott pacing in front of the American flag.  Sheila was a voice on a con-call.  When she moved on in 2007, Walid Abu-Hadba was given the reigns.  Personally, I don’t ever recall even seeing his face.  I think I might recall hearing his voice on some con-calls, but for all intents and purposes he was invisible to me.  Perhaps this was the beginning of my carelessness around seeking “visibility.” Fast forward to Build 2011.  First off, we have no PDC – we have Build.  Microsoft had made an 11 year investment by this time in building an organization to make its technology relevant to developers.  One would think such an org would be in the driver’s seat of such an event, but we see Windows product group people on the podiums.  Watching, I could see the messaging unfold… but no story.  It was like the old days.  Demos and PowerPoints by team members building the tech, and in many cases VPs.  The ensuing confusion is almost legendary now.  Windows 8 was, and is, a pretty big deal… but who is telling the story – not just features and benefits, but the story around how it all fits together. Having been out of Microsoft for two years now, and looking in, I can only conclude that the “DPE of old” has at best been emasculated, and at worst been completely marginalized by internal politics, or perhaps the eternal march of the corporate entropy generator that resides at all large companies.  I don’t think this is a good thing for anyone. And now, back to Sanjay who is the father of Microsoft DPE… I noticed that he has moved back to India and is doing start-up work.  His current company Indix looks to be doing some interesting things with “big data” and here’s their stack: Nary a trace of anything Microsoft.  What could account for this?  I wonder….  Better availability of labor and expertise in India for this stack?  Donno, but even in India, leet R and Hadoop skills have to be hard to find. Technical superiority?  This, I sincerely doubt. This stack, with SanjayP’s name as CEO leaves me with an unsettling feeling.  If he did believe, he no longer does.  One doesn’t place bets with real money on things they don’t believe in.  Perhaps he never did believe, and was a corporate creature seeking to find a niche for himself after which he manipulated me and others.  Or perhaps… anger… be it passive aggression or an outright “in your face F*** you” to his former masters. I guess in the end, only he knows the true reason… But I have my theory...

  Read the article

• Performance considerations for common SQL queries

  - by Jim Giercyk

  Originally posted on: http://geekswithblogs.net/NibblesAndBits/archive/2013/10/16/performance-considerations-for-common-sql-queries.aspxSQL offers many different methods to produce the same results.  There is a never-ending debate between SQL developers as to the “best way” or the “most efficient way” to render a result set.  Sometimes these disputes even come to blows….well, I am a lover, not a fighter, so I decided to collect some data that will prove which way is the best and most efficient.  For the queries below, I downloaded the test database from SQLSkills:  http://www.sqlskills.com/sql-server-resources/sql-server-demos/.  There isn’t a lot of data, but enough to prove my point: dbo.member has 10,000 records, and dbo.payment has 15,554.  Our result set contains 6,706 records. The following queries produce an identical result set; the result set contains aggregate payment information for each member who has made more than 1 payment from the dbo.payment table and the first and last name of the member from the dbo.member table.   /*************/ /* Sub Query  */ /*************/ SELECT  a.[Member Number] ,         m.lastname ,         m.firstname ,         a.[Number Of Payments] ,         a.[Average Payment] ,         a.[Total Paid] FROM    ( SELECT    member_no 'Member Number' ,                     AVG(payment_amt) 'Average Payment' ,                     SUM(payment_amt) 'Total Paid' ,                     COUNT(Payment_No) 'Number Of Payments'           FROM      dbo.payment           GROUP BY  member_no           HAVING    COUNT(Payment_No) > 1         ) a         JOIN dbo.member m ON a.[Member Number] = m.member_no         /***************/ /* Cross Apply  */ /***************/ SELECT  ca.[Member Number] ,         m.lastname ,         m.firstname ,         ca.[Number Of Payments] ,         ca.[Average Payment] ,         ca.[Total Paid] FROM    dbo.member m         CROSS APPLY ( SELECT    member_no 'Member Number' ,                                 AVG(payment_amt) 'Average Payment' ,                                 SUM(payment_amt) 'Total Paid' ,                                 COUNT(Payment_No) 'Number Of Payments'                       FROM      dbo.payment                       WHERE     member_no = m.member_no                       GROUP BY  member_no                       HAVING    COUNT(Payment_No) > 1                     ) ca /********/                    /* CTEs  */ /********/ ; WITH    Payments           AS ( SELECT   member_no 'Member Number' ,                         AVG(payment_amt) 'Average Payment' ,                         SUM(payment_amt) 'Total Paid' ,                         COUNT(Payment_No) 'Number Of Payments'                FROM     dbo.payment                GROUP BY member_no                HAVING   COUNT(Payment_No) > 1              ),         MemberInfo           AS ( SELECT   p.[Member Number] ,                         m.lastname ,                         m.firstname ,                         p.[Number Of Payments] ,                         p.[Average Payment] ,                         p.[Total Paid]                FROM     dbo.member m                         JOIN Payments p ON m.member_no = p.[Member Number]              )     SELECT  *     FROM    MemberInfo /************************/ /* SELECT with Grouping   */ /************************/ SELECT  p.member_no 'Member Number' ,         m.lastname ,         m.firstname ,         COUNT(Payment_No) 'Number Of Payments' ,         AVG(payment_amt) 'Average Payment' ,         SUM(payment_amt) 'Total Paid' FROM    dbo.payment p         JOIN dbo.member m ON m.member_no = p.member_no GROUP BY p.member_no ,         m.lastname ,         m.firstname HAVING  COUNT(Payment_No) > 1   We can see what is going on in SQL’s brain by looking at the execution plan.  The Execution Plan will demonstrate which steps and in what order SQL executes those steps, and what percentage of batch time each query takes.  SO….if I execute all 4 of these queries in a single batch, I will get an idea of the relative time SQL takes to execute them, and how it renders the Execution Plan.  We can settle this once and for all.  Here is what SQL did with these queries:   Not only did the queries take the same amount of time to execute, SQL generated the same Execution Plan for each of them.  Everybody is right…..I guess we can all finally go to lunch together!  But wait a second, I may not be a fighter, but I AM an instigator.     Let’s see how a table variable stacks up.  Here is the code I executed: /********************/ /*  Table Variable  */ /********************/ DECLARE @AggregateTable TABLE     (       member_no INT ,       AveragePayment MONEY ,       TotalPaid MONEY ,       NumberOfPayments MONEY     ) INSERT  @AggregateTable         SELECT  member_no 'Member Number' ,                 AVG(payment_amt) 'Average Payment' ,                 SUM(payment_amt) 'Total Paid' ,                 COUNT(Payment_No) 'Number Of Payments'         FROM    dbo.payment         GROUP BY member_no         HAVING  COUNT(Payment_No) > 1   SELECT  at.member_no 'Member Number' ,         m.lastname ,         m.firstname ,         at.NumberOfPayments 'Number Of Payments' ,         at.AveragePayment 'Average Payment' ,         at.TotalPaid 'Total Paid' FROM    @AggregateTable at         JOIN dbo.member m ON m.member_no = at.member_no In the interest of keeping things in groupings of 4, I removed the last query from the previous batch and added the table variable query.  Here’s what I got:     Since we first insert into the table variable, then we read from it, the Execution Plan renders 2 steps.  BUT, the combination of the 2 steps is only 22% of the batch.  It is actually faster than the other methods even though it is treated as 2 separate queries in the Execution Plan.  The argument I often hear against Table Variables is that SQL only estimates 1 row for the table size in the Execution Plan.  While this is true, the estimate does not come in to play until you read from the table variable.  In this case, the table variable had 6,706 rows, but it still outperformed the other queries.  People argue that table variables should only be used for hash or lookup tables.  The fact is, you have control of what you put IN to the variable, so as long as you keep it within reason, these results suggest that a table variable is a viable alternative to sub-queries. If anyone does volume testing on this theory, I would be interested in the results.  My suspicion is that there is a breaking point where efficiency goes down the tubes immediately, and it would be interesting to see where the threshold is. Coding SQL is a matter of style.  If you’ve been around since they introduced DB2, you were probably taught a little differently than a recent computer science graduate.  If you have a company standard, I strongly recommend you follow it.    If you do not have a standard, generally speaking, there is no right or wrong answer when talking about the efficiency of these types of queries, and certainly no hard-and-fast rule.  Volume and infrastructure will dictate a lot when it comes to performance, so your results may vary in your environment.  Download the database and try it!

  Read the article

• NET Math Libraries

  - by JoshReuben

  NET Mathematical Libraries   .NET Builder for Matlab The MathWorks Inc. - http://www.mathworks.com/products/netbuilder/ MATLAB Builder NE generates MATLAB based .NET and COM components royalty-free deployment creates the components by encrypting MATLAB functions and generating either a .NET or COM wrapper around them. .NET/Link for Mathematica www.wolfram.com a product that 2-way integrates Mathematica and Microsoft's .NET platform call .NET from Mathematica - use arbitrary .NET types directly from the Mathematica language. use and control the Mathematica kernel from a .NET program. turns Mathematica into a scripting shell to leverage the computational services of Mathematica. write custom front ends for Mathematica or use Mathematica as a computational engine for another program comes with full source code. Leverages MathLink - a Wolfram Research's protocol for sending data and commands back and forth between Mathematica and other programs. .NET/Link abstracts the low-level details of the MathLink C API. Extreme Optimization http://www.extremeoptimization.com/ a collection of general-purpose mathematical and statistical classes built for the.NET framework. It combines a math library, a vector and matrix library, and a statistics library in one package. download the trial of version 4.0 to try it out. Multi-core ready - Full support for Task Parallel Library features including cancellation. Broad base of algorithms covering a wide range of numerical techniques, including: linear algebra (BLAS and LAPACK routines), numerical analysis (integration and differentiation), equation solvers. Mathematics leverages parallelism using .NET 4.0's Task Parallel Library. Basic math: Complex numbers, 'special functions' like Gamma and Bessel functions, numerical differentiation. Solving equations: Solve equations in one variable, or solve systems of linear or nonlinear equations. Curve fitting: Linear and nonlinear curve fitting, cubic splines, polynomials, orthogonal polynomials. Optimization: find the minimum or maximum of a function in one or more variables, linear programming and mixed integer programming. Numerical integration: Compute integrals over finite or infinite intervals, over 2D and higher dimensional regions. Integrate systems of ordinary differential equations (ODE's). Fast Fourier Transforms: 1D and 2D FFT's using managed or fast native code (32 and 64 bit) BigInteger, BigRational, and BigFloat: Perform operations with arbitrary precision. Vector and Matrix Library Real and complex vectors and matrices. Single and double precision for elements. Structured matrix types: including triangular, symmetrical and band matrices. Sparse matrices. Matrix factorizations: LU decomposition, QR decomposition, singular value decomposition, Cholesky decomposition, eigenvalue decomposition. Portability and performance: Calculations can be done in 100% managed code, or in hand-optimized processor-specific native code (32 and 64 bit). Statistics Data manipulation: Sort and filter data, process missing values, remove outliers, etc. Supports .NET data binding. Statistical Models: Simple, multiple, nonlinear, logistic, Poisson regression. Generalized Linear Models. One and two-way ANOVA. Hypothesis Tests: 12 14 hypothesis tests, including the z-test, t-test, F-test, runs test, and more advanced tests, such as the Anderson-Darling test for normality, one and two-sample Kolmogorov-Smirnov test, and Levene's test for homogeneity of variances. Multivariate Statistics: K-means cluster analysis, hierarchical cluster analysis, principal component analysis (PCA), multivariate probability distributions. Statistical Distributions: 25 29 continuous and discrete statistical distributions, including uniform, Poisson, normal, lognormal, Weibull and Gumbel (extreme value) distributions. Random numbers: Random variates from any distribution, 4 high-quality random number generators, low discrepancy sequences, shufflers. New in version 4.0 (November, 2010) Support for .NET Framework Version 4.0 and Visual Studio 2010 TPL Parallellized – multicore ready sparse linear program solver - can solve problems with more than 1 million variables. Mixed integer linear programming using a branch and bound algorithm. special functions: hypergeometric, Riemann zeta, elliptic integrals, Frensel functions, Dawson's integral. Full set of window functions for FFT's. Product  Price Update subscription Single Developer License $999  $399  Team License (3 developers) $1999  $799  Department License (8 developers) $3999  $1599  Site License (Unlimited developers in one physical location) $7999  $3199    NMath http://www.centerspace.net .NET math and statistics libraries matrix and vector classes random number generators Fast Fourier Transforms (FFTs) numerical integration linear programming linear regression curve and surface fitting optimization hypothesis tests analysis of variance (ANOVA) probability distributions principal component analysis cluster analysis built on the Intel Math Kernel Library (MKL), which contains highly-optimized, extensively-threaded versions of BLAS (Basic Linear Algebra Subroutines) and LAPACK (Linear Algebra PACKage). Product  Price Update subscription Single Developer License $1295 $388 Team License (5 developers) $5180 $1554   DotNumerics http://www.dotnumerics.com/NumericalLibraries/Default.aspx free DotNumerics is a website dedicated to numerical computing for .NET that includes a C# Numerical Library for .NET containing algorithms for Linear Algebra, Differential Equations and Optimization problems. The Linear Algebra library includes CSLapack, CSBlas and CSEispack, ports from Fortran to C# of LAPACK, BLAS and EISPACK, respectively. Linear Algebra (CSLapack, CSBlas and CSEispack). Systems of linear equations, eigenvalue problems, least-squares solutions of linear systems and singular value problems. Differential Equations. Initial-value problem for nonstiff and stiff ordinary differential equations ODEs (explicit Runge-Kutta, implicit Runge-Kutta, Gear's BDF and Adams-Moulton). Optimization. Unconstrained and bounded constrained optimization of multivariate functions (L-BFGS-B, Truncated Newton and Simplex methods).   Math.NET Numerics http://numerics.mathdotnet.com/ free an open source numerical library - includes special functions, linear algebra, probability models, random numbers, interpolation, integral transforms. A merger of dnAnalytics with Math.NET Iridium in addition to a purely managed implementation will also support native hardware optimization. constants & special functions complex type support real and complex, dense and sparse linear algebra (with LU, QR, eigenvalues, ... decompositions) non-uniform probability distributions, multivariate distributions, sample generation alternative uniform random number generators descriptive statistics, including order statistics various interpolation methods, including barycentric approaches and splines numerical function integration (quadrature) routines integral transforms, like fourier transform (FFT) with arbitrary lengths support, and hartley spectral-space aware sequence manipulation (signal processing) combinatorics, polynomials, quaternions, basic number theory. parallelized where appropriate, to leverage multi-core and multi-processor systems fully managed or (if available) using native libraries (Intel MKL, ACMS, CUDA, FFTW) provides a native facade for F# developers

  Read the article

• Partition Wise Joins

  - by jean-pierre.dijcks

  Some say they are the holy grail of parallel computing and PWJ is the basis for a shared nothing system and the only join method that is available on a shared nothing system (yes this is oversimplified!). The magic in Oracle is of course that is one of many ways to join data. And yes, this is the old flexibility vs. simplicity discussion all over, so I won't go there... the point is that what you must do in a shared nothing system, you can do in Oracle with the same speed and methods. The Theory A partition wise join is a join between (for simplicity) two tables that are partitioned on the same column with the same partitioning scheme. In shared nothing this is effectively hard partitioning locating data on a specific node / storage combo. In Oracle is is logical partitioning. If you now join the two tables on that partitioned column you can break up the join in smaller joins exactly along the partitions in the data. Since they are partitioned (grouped) into the same buckets, all values required to do the join live in the equivalent bucket on either sides. No need to talk to anyone else, no need to redistribute data to anyone else... in short, the optimal join method for parallel processing of two large data sets. PWJ's in Oracle Since we do not hard partition the data across nodes in Oracle we use the Partitioning option to the database to create the buckets, then set the Degree of Parallelism (or run Auto DOP - see here) and get our PWJs. The main questions always asked are: How many partitions should I create? What should my DOP be? In a shared nothing system the answer is of course, as many partitions as there are nodes which will be your DOP. In Oracle we do want you to look at the workload and concurrency, and once you know that to understand the following rules of thumb. Within Oracle we have more ways of joining of data, so it is important to understand some of the PWJ ideas and what it means if you have an uneven distribution across processes. Assume we have a simple scenario where we partition the data on a hash key resulting in 4 hash partitions (H1 -H4). We have 2 parallel processes that have been tasked with reading these partitions (P1 - P2). The work is evenly divided assuming the partitions are the same size and we can scan this in time t1 as shown below. Now assume that we have changed the system and have a 5th partition but still have our 2 workers P1 and P2. The time it takes is actually 50% more assuming the 5th partition has the same size as the original H1 - H4 partitions. In other words to scan these 5 partitions, the time t2 it takes is not 1/5th more expensive, it is a lot more expensive and some other join plans may now start to look exciting to the optimizer. Just to post the disclaimer, it is not as simple as I state it here, but you get the idea on how much more expensive this plan may now look... Based on this little example there are a few rules of thumb to follow to get the partition wise joins. First, choose a DOP that is a factor of two (2). So always choose something like 2, 4, 8, 16, 32 and so on... Second, choose a number of partitions that is larger or equal to 2* DOP. Third, make sure the number of partitions is divisible through 2 without orphans. This is also known as an even number... Fourth, choose a stable partition count strategy, which is typically hash, which can be a sub partitioning strategy rather than the main strategy (range - hash is a popular one). Fifth, make sure you do this on the join key between the two large tables you want to join (and this should be the obvious one...). Translating this into an example: DOP = 8 (determined based on concurrency or by using Auto DOP with a cap due to concurrency) says that the number of partitions >= 16. Number of hash (sub) partitions = 32, which gives each process four partitions to work on. This number is somewhat arbitrary and depends on your data and system. In this case my main reasoning is that if you get more room on the box you can easily move the DOP for the query to 16 without repartitioning... and of course it makes for no leftovers on the table... And yes, we recommend up-to-date statistics. And before you start complaining, do read this post on a cool way to do stats in 11.

  Read the article

• Independence Day for Software Components &ndash; Loosening Coupling by Reducing Connascence

  - by Brian Schroer

  Today is Independence Day in the USA, which got me thinking about loosely-coupled “independent” software components. I was reminded of a video I bookmarked quite a while ago of Jim Weirich’s “Grand Unified Theory of Software Design” talk at MountainWest RubyConf 2009. I finally watched that video this morning. I highly recommend it. In the video, Jim talks about software connascence. The dictionary definition of connascence (con-NAY-sense) is: 1. The common birth of two or more at the same time 2. That which is born or produced with another. 3. The act of growing together. The brief Wikipedia page about Connascent Software Components says that: Two software components are connascent if a change in one would require the other to be modified in order to maintain the overall correctness of the system. Connascence is a way to characterize and reason about certain types of complexity in software systems. The term was introduced to the software world in Meilir Page-Jones’ 1996 book “What Every Programmer Should Know About Object-Oriented Design”. The middle third of that book is the author’s proposed graphical notation for describing OO designs. UML became the standard about a year later, so a revised version of the book was published in 1999 as “Fundamentals of Object-Oriented Design in UML”. Weirich says that the third part of the book, in which Page-Jones introduces the concept of connascence “is worth the price of the entire book”. (The price of the entire book, by the way, is not much – I just bought a used copy on Amazon for $1.36, so that was a pretty low-risk investment. I’m looking forward to getting the book and learning about connascence from the original source.) Meanwhile, here’s my summary of Weirich’s summary of Page-Jones writings about connascence: The stronger the form of connascence, the more difficult and costly it is to change the elements in the relationship. Some of the connascence types, ordered from weak to strong are: Connascence of Name Connascence of name is when multiple components must agree on the name of an entity. If you change the name of a method or property, then you need to change all references to that method or property. Duh. Connascence of name is unavoidable, assuming your objects are actually used. My main takeaway about connascence of name is that it emphasizes the importance of giving things good names so you don’t need to go changing them later. Connascence of Type Connascence of type is when multiple components must agree on the type of an entity. I assume this is more of a problem for languages without compilers (especially when used in apps without tests). I know it’s an issue with evil JavaScript type coercion. Connascence of Meaning Connascence of meaning is when multiple components must agree on the meaning of particular values, e.g that “1” means normal customer and “2” means preferred customer. The solution to this is to use constants or enums instead of “magic” strings or numbers, which reduces the coupling by changing the connascence form from “meaning” to “name”. Connascence of Position Connascence of positions is when multiple components must agree on the order of values. This refers to methods with multiple parameters, e.g.: eMailer.Send("[email protected]", "[email protected]", "Your order is complete", "Order completion notification"); The more parameters there are, the stronger the connascence of position is between the component and its callers. In the example above, it’s not immediately clear when reading the code which email addresses are sender and receiver, and which of the final two strings are subject vs. body. Connascence of position could be improved to connascence of type by replacing the parameter list with a struct or class. This “introduce parameter object” refactoring might be overkill for a method with 2 parameters, but would definitely be an improvement for a method with 10 parameters. This points out two “rules” of connascence:  The Rule of Degree: The acceptability of connascence is related to the degree of its occurrence. The Rule of Locality: Stronger forms of connascence are more acceptable if the elements involved are closely related. For example, positional arguments in private methods are less problematic than in public methods. Connascence of Algorithm Connascence of algorithm is when multiple components must agree on a particular algorithm. Be DRY – Don’t Repeat Yourself. If you have “cloned” code in multiple locations, refactor it into a common function.   Those are the “static” forms of connascence. There are also “dynamic” forms, including… Connascence of Execution Connascence of execution is when the order of execution of multiple components is important. Consumers of your class shouldn’t have to know that they have to call an .Initialize method before it’s safe to call a .DoSomething method. Connascence of Timing Connascence of timing is when the timing of the execution of multiple components is important. I’ll have to read up on this one when I get the book, but assume it’s largely about threading. Connascence of Identity Connascence of identity is when multiple components must reference the entity. The example Weirich gives is when you have two instances of the “Bob” Employee class and you call the .RaiseSalary method on one and then the .Pay method on the other does the payment use the updated salary?   Again, this is my summary of a summary, so please be forgiving if I misunderstood anything. Once I get/read the book, I’ll make corrections if necessary and share any other useful information I might learn.   See Also: Gregory Brown: Ruby Best Practices Issue #24: Connascence as a Software Design Metric (That link is failing at the time I write this, so I had to go to the Google cache of the page.)

  Read the article

• An Alphabet of Eponymous Aphorisms, Programming Paradigms, Software Sayings, Annoying Alliteration

  - by Brian Schroer

  Malcolm Anderson blogged about “Einstein’s Razor” yesterday, which reminded me of my favorite software development “law”, the name of which I can never remember. It took much Wikipedia-ing to find it (Hofstadter’s Law – see below), but along the way I compiled the following list: Amara’s Law: We tend to overestimate the effect of a technology in the short run and underestimate the effect in the long run. Brook’s Law: Adding manpower to a late software project makes it later. Clarke’s Third Law: Any sufficiently advanced technology is indistinguishable from magic. Law of Demeter: Each unit should only talk to its friends; don't talk to strangers. Einstein’s Razor: “Make things as simple as possible, but not simpler” is the popular paraphrase, but what he actually said was “It can scarcely be denied that the supreme goal of all theory is to make the irreducible basic elements as simple and as few as possible without having to surrender the adequate representation of a single datum of experience”, an overly complicated quote which is an obvious violation of Einstein’s Razor. (You can tell by looking at a picture of Einstein that the dude was hardly an expert on razors or other grooming apparati.) Finagle's Law of Dynamic Negatives: Anything that can go wrong, will—at the worst possible moment. - O'Toole's Corollary: The perversity of the Universe tends towards a maximum. Greenspun's Tenth Rule: Any sufficiently complicated C or Fortran program contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Common Lisp. (Morris’s Corollary: “…including Common Lisp”) Hofstadter's Law: It always takes longer than you expect, even when you take into account Hofstadter's Law. Issawi’s Omelet Analogy: One cannot make an omelet without breaking eggs - but it is amazing how many eggs one can break without making a decent omelet. Jackson’s Rules of Optimization: Rule 1: Don't do it. Rule 2 (for experts only): Don't do it yet. Kaner’s Caveat: A program which perfectly meets a lousy specification is a lousy program. Liskov Substitution Principle (paraphrased): Functions that use pointers or references to base classes must be able to use objects of derived classes without knowing it Mason’s Maxim: Since human beings themselves are not fully debugged yet, there will be bugs in your code no matter what you do. Nils-Peter Nelson’s Nil I/O Rule: The fastest I/O is no I/O.    Occam's Razor: The simplest explanation is usually the correct one. Parkinson’s Law: Work expands so as to fill the time available for its completion. Quentin Tarantino’s Pie Principle: “…you want to go home have a drink and go and eat pie and talk about it.” (OK, he was talking about movies, not software, but I couldn’t find a “Q” quote about software. And wouldn’t it be cool to write a program so great that the users want to eat pie and talk about it?) Raymond’s Rule: Computer science education cannot make anybody an expert programmer any more than studying brushes and pigment can make somebody an expert painter.  Sowa's Law of Standards: Whenever a major organization develops a new system as an official standard for X, the primary result is the widespread adoption of some simpler system as a de facto standard for X. Turing’s Tenet: We shall do a much better programming job, provided we approach the task with a full appreciation of its tremendous difficulty, provided that we respect the intrinsic limitations of the human mind and approach the task as very humble programmers.  Udi Dahan’s Race Condition Rule: If you think you have a race condition, you don’t understand the domain well enough. These rules didn’t exist in the age of paper, there is no reason for them to exist in the age of computers. When you have race conditions, go back to the business and find out actual rules. Van Vleck’s Kvetching: We know about as much about software quality problems as they knew about the Black Plague in the 1600s. We've seen the victims' agonies and helped burn the corpses. We don't know what causes it; we don't really know if there is only one disease. We just suffer -- and keep pouring our sewage into our water supply. Wheeler’s Law: All problems in computer science can be solved by another level of indirection... Except for the problem of too many layers of indirection. Wheeler also said “Compatibility means deliberately repeating other people's mistakes.”. The Wrong Road Rule of Mr. X (anonymous): No matter how far down the wrong road you've gone, turn back. Yourdon’s Rule of Two Feet: If you think your management doesn't know what it's doing or that your organisation turns out low-quality software crap that embarrasses you, then leave. Zawinski's Law of Software Envelopment: Every program attempts to expand until it can read mail. Zawinski is also responsible for “Some people, when confronted with a problem, think 'I know, I'll use regular expressions.' Now they have two problems.” He once commented about X Windows widget toolkits: “Using these toolkits is like trying to make a bookshelf out of mashed potatoes.”

  Read the article

< Previous Page | 47 48 49 50 51 52 53 54 55 56 57 58  | Next Page >