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• Sendmail Tuning For Batch Mail Jobs

  - by Kyle Brandt

  I have a webservers that send out emails to a sendmail relay server as a batch job. The emails need to be accepted by the relay sendmail server as fast as possible, however, they do not need to go out (be relayed) very quickly. I am seeing a couple timeouts once and a while from the webserver trying to connect to the relay server. The load currently is about 30 emails a second for a couple minutes. There are quite a few tuning options for sendmail in the sendmail tuning guide. What I am focusing on now is the Delivery Mode: Delivery Mode There are a number of delivery modes that sendmail can operate in, set by the DeliveryMode ( d) configuration option. These modes specify how quickly mail will be delivered. Legal modes are: i deliver interactively (synchronously) b deliver in background (asynchronously) q queue only (don't deliver) d defer delivery attempts (don't deliver) There are tradeoffs. Mode i gives the sender the quickest feedback, but may slow down some mailers and is hardly ever necessary. Mode b delivers promptly but can cause large numbers of processes if you have a mailer that takes a long time to deliver a message. Mode q minimizes the load on your machine, but means that delivery may be delayed for up to the queue interval. Mode d is identical to mode q except that it also prevents lookups in maps including the -D flag from working during the initial queue phase; it is intended for ``dial on demand'' sites where DNS lookups might cost real money. Some simple error messages (e.g., host unknown during the SMTP protocol) will be delayed using this mode. Mode b is the usual default. If you run in mode q (queue only), d (defer), or b (deliver in background) sendmail will not expand aliases and follow .forward files upon initial receipt of the mail. This speeds up the response to RCPT commands. Mode i should not be used by the SMTP server. I currently have the CentOS default modes: Sendmail.cf: DeliveryMode=background Submit.cf: DeliveryMode=i Is sendmail.cf/mc for outgoing email from relay (to the intertubes) and sumbit.cf/mc for incoming eamil (from my webservers). Would it make sense to change the outgoing delivery mode to queue? If I did, what would the outbound email flow behave like? If this is the right thing to do, can anyone show me example mc configurations for this change? If it isn't, what recommendations are there for these constraints?

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• Computer experiencing slowdowns and lockups despite low cpu useage

  - by user157145

  my setup i5-2300 nvidia gtx 550 ti 6 gigs ram 600 w ocz modular psu recently reformatted and already experiencing drastic slowdown as soon as windows comes up, including repeated lockups with multiple various programs reporting that they are not responsive, then recovering after 10-30 seconds. ive checked memory and hard drive both of which come out fine. despite my plethura of worthless antiviral software im forced to assume that my illicit downloading practices have lead me into some comp trouble that i cant seem to determine. i have used ccleaner, search and destroy and malware bytes, all of which have found nothing to indicate what is causing this massive slowdown. in addition according to my resource manager my computer is operating at a load of only 30-50 percent CPU useage and 60 ram useage but taking 5-10 seconds to load files and open folders, and repeated lockups of multiple programs, especially firefox which seems to go unresponsive every 2-3 minutes. any help would be appreciated, i used a program called OTL by old timer, but cant make any sense of the results i was given. any help or suggestions would be appreciated, thank you for taking the time to read this i have avast but it didnt even find anything when i had it do a full system scan, so im thinking its clueless(also nortons, avg, and ad-aware). i also have mse but it has yet to complete a full scan it takes so long (i left it on last night but when i woke up my computer had a problem and had to restart). my hard drive has 300 gigs out of 1tb open and i already used hd tune pro, which said my harddrive was fine and its not a ssd. also im a noob at comps and only have the hd that is currently inside the computer in addition im not sure if studdering is the issue im suffering. my problem is that during my typing of these responses firefox has gone "not responsive" at least 5 times, each for times of about 5-10 seconds. when i try to control alt delete to bring up windows task manager it took 20 seconds. essentially its that my computer goes super slow at bringing up anything, or taking any action whatsoever that opens a program or file and has repeated incidents where i cant even click on whatever im trying to do because it locks up. the confusing thing about these incidents is that its right after restarting where there are minimal programs running and the computer and memory load is light.

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• DVD playback with Windows Media Player 11 works fine, but when copied to HDD and then played back, t

  - by stakx

  I have several DVDs with short documentaries on it. Since the notebook I'm using (a Dell Latitude E6400) has only one DVD drive, and I might play back those short movies very often, I thought of copying them to the HDD and playing them back from there. However, I've run into a problem, namely stuttering audio. Problem description: When I play back these movies directly from DVD (with Windows Media Player 11 under Windows Vista), everything works fine. Smooth video, no significant audio problems (only the occasional click). But as soon as I copy any of these DVDs to the HDD and try to play them back from there (e.g. using the wmpdvd://drive/title/chapter?contentdir=path protocol, I get stuttering audio — audio playback sounds like a machine gun for a third of a second or so, approx. every 8 seconds. I have tried converting the VOB files from the DVD to another format (ie. ripping), but that resulted in a noticeable downgrade of picture quality. Therefore I thought it best to keep the files in their original format, if possible. Still, I suspect that the stuttering audio is due to some (de-)muxing problem, and that changing the file format might help. (After all, video playback is fine; therefore I don't think that the hardware is too slow for playback.) Only thing is, I don't know how to convert the VOB files to another Windows Media Player-compatible format without quality loss. I hope someone can help me, or give me further pointers on things I could try out to get HDD playback to work without the problem described. Some things I've tried so far, without any success: VOB2MPG, in order to convert the .vob file to a .mpg file. But that changes only the A/V container, not the content. No re-encoding takes place at all. Re-encoding with MPlayer/MEncoder. Lots of quality loss there, and I frankly haven't got the time to test all possible settings combinations available. Disabling all plug-ins, equalizers, etc. in Windows Media Player. Disabling all hardware acceleration on the audio playback device. Further info on the VOB files I'm trying to playback: The video format is MPEG ES, PAL 720x576 pixels @ 24/25 frames per second. The sound stream is uncompressed PCM, 16-bit stereo @ 48kHz. (Might it help if I somehow re-encoded the sound stream at a lower resolution, or as an MP3? If so, how would I do this without changing the video stream?) P.S.: I am limited to using Windows Media Player (11). (I previously tried MPlayer btw., but the video playback quality was surprisingly bad.)

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• How do i enable innodb on ubuntu server 10.04

  - by Matt

  Here is my entire my.cnf [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] key_buffer = 224M sort_buffer_size = 4M read_buffer_size = 4M read_rnd_buffer_size = 4M myisam_sort_buffer_size = 12M query_cache_size = 44M # # * 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/ And here is my show engines call....i have no idea what i need to do to enable innodb show engines; +------------+---------+----------------------------------------------------------------+--------------+------+------------+ | Engine | Support | Comment | Transactions | XA | Savepoints | +------------+---------+----------------------------------------------------------------+--------------+------+------------+ | MyISAM | DEFAULT | Default engine as of MySQL 3.23 with great performance | NO | NO | NO | | MRG_MYISAM | YES | Collection of identical MyISAM tables | NO | NO | NO | | BLACKHOLE | YES | /dev/null storage engine (anything you write to it disappears) | NO | NO | NO | | CSV | YES | CSV storage engine | NO | NO | NO | | MEMORY | YES | Hash based, stored in memory, useful for temporary tables | NO | NO | NO | | FEDERATED | NO | Federated MySQL storage engine | NULL | NULL | NULL | | ARCHIVE | YES | Archive storage engine | NO | NO | NO | +------------+---------+----------------------------------------------------------------+--------------+------+------------+ 7 rows in set (0.00 sec)

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• Linux per-process resource limits - a deep Red Hat Mystery

  - by BobBanana

  I have my own multithreaded C program which scales in speed smoothly with the number of CPU cores.. I can run it with 1, 2, 3, etc threads and get linear speedup.. up to about 5.5x speed on a 6-core CPU on a Ubuntu Linux box. I had an opportunity to run the program on a very high end Sunfire x4450 with 4 quad-core Xeon processors, running Red Hat Enterprise Linux. I was eagerly anticipating seeing how fast the 16 cores could run my program with 16 threads.. But it runs at the same speed as just TWO threads! Much hair-pulling and debugging later, I see that my program really is creating all the threads, they really are running simultaneously, but the threads themselves are slower than they should be. 2 threads runs about 1.7x faster than 1, but 3, 4, 8, 10, 16 threads all run at just net 1.9x! I can see all the threads are running (not stalled or sleeping), they're just slow. To check that the HARDWARE wasn't at fault, I ran SIXTEEN copies of my program independently, simultaneously. They all ran at full speed. There really are 16 cores and they really do run at full speed and there really is enough RAM (in fact this machine has 64GB, and I only use 1GB per process). So, my question is if there's some OPERATING SYSTEM explanation, perhaps some per-process resource limit which automatically scales back thread scheduling to keep one process from hogging the machine. Clues are: My program does not access the disk or network. It's CPU limited. Its speed scales linearly on a single CPU box in Ubuntu Linux with a hexacore i7 for 1-6 threads. 6 threads is effectively 6x speedup. My program never runs faster than 2x speedup on this 16 core Sunfire Xeon box, for any number of threads from 2-16. Running 16 copies of my program single threaded runs perfectly, all 16 running at once at full speed. top shows 1600% of CPUs allocated. /proc/cpuinfo shows all 16 cores running at full 2.9GHz speed (not low frequency idle speed of 1.6GHz) There's 48GB of RAM free, it is not swapping. What's happening? Is there some process CPU limit policy? How could I measure it if so? What else could explain this behavior? Thanks for your ideas to solve this, the Great Xeon Slowdown Mystery of 2010!

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• Wireless Network Performance Issues

  - by colithium

  My brand new Dell XPS system has been running flawlessly except its abysmal download speeds. I have tried isolating every variable I could possibly think of but I can't figure out the problem. I've talked to Dell and Belkin without making progress (thought I'd try). Here are the speeds: Note that most of the time, upload speeds are actually much faster than download speeds (around 4.0 Mb/s which is better than most other devices on the network) It's not the ISP. The slowdown happens even when transferring files inside the network. Plus every other wireless device gets approximately this: It's not the wireless router. It's a Lynksis WRT160N v1 with the latest firmware (1.02.2). Plus everything else connected to it has normal speeds. It's not the browser. Speeds are the same in IE, FF, and when transferring files with Windows between computers. It's not the wireless adapter. I've tried a Belkin N Wireless USB Adapter (which works fine on another computer) and a Dell Wireless Draft 802.11n WLAN Mini-Card. They have the same slow speeds when connected to the problem computer. It's not the adapter connection. One adapter used USB and the other is a Mini-Card. It's not antenna placement. With the same antenna position and the same device, I get different speeds when connected to the problem computer vs a good computer. Plus everything reports the connection speed as at least 11Mbps and good signal strength. I've tried disabling IPv6 since it sometimes causes weird problems. I've tried disabling Windows Firewall/anti-virus. I've ensured the computer has updated drivers for both adapters. I've ensured that Windows is up to date and so is the BIOS. For the USB adapter I ensured that that USB port functioned at normal speeds with other USB devices. What else could it possibly be? I finally received my copy of Windows 7 and will be trying that. I'd rather not install Windows 7 because of a particular program that will stop working so a solution besides that is welcome. Specs: Vista x64 Core i7 920 6GB RAM 500GB HD GTX 260

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• Why is the server performance so poor? What can be done to improve the speed of the server?

  - by fslsyed

  Very slow processing using Windows Server2008 R2 Standard with Service Pack One. Situation: Read a text file using the text data to populate a series of MS Sql tables. The converted data is used to generate monthly PDF invoice files; the PDF files are saved directly to the hard drive. The application is multi-threading with one thread used for the text conversion and three threads for PDF invoice generation. The text conversion is occurring concurrently with the invoice generation. Application Software: C# using Microsoft Visual Studio 2010 Ultimate. Crystal Report Writer 2011 with runtime 13_0_3 64 bit version. Targeted platform is x64; also tested as x86, and Any CPU with similar results. Microsoft .NET Framework 4.0. Microsoft Sql 2008 Issue: The software is running very slowly. The conversion of the text file is approximately six hundred fifty records per second and generation of the PDF files is approximately twelve invoices per minute. The text file to be converted is six hundred Meg with seven thousand invoices to be generated. The software was installed on three different machines from the same distribution files. The same text file was converted on each machine. The user executing the application was an administrator on each machine. The only variances were the machine and operating system. The configurations are as follows: Server: Operating System: Windows Server2008 R2 Standard 64-bit (6.1, Build7601) SP1 Service Pack: System Manufacturer: IBM System Model: System x3550 M3-[7944AC1]- BIOS: Default System BIOS Processor: Intel® Xeon® CPU E5620@ 2.4GHz (16 CPUs) Memory: 16384MB Notebook: Operating System: Windows 7 Home Premium Standard 64-bit (6.1, Build7601) System Manufacturer: Hewlett-Packard System Model: HP Pavilion dv7 Notebook PC BIOS: Default System BIOS Processor: AMD Phenom II N640 Dual-Core Processor 2.9GHz (2 CPUs) Memory: 6144MB Desktop: Operating System: Windows 7 Professional 64-bit (6.1, Build7601) SP1 System Manufacturer: Dell Inc. System Model: OptiPlex 960 BIOS: Phoenix ROM BIOS PLUS Version 1.10 A11 Processor: Intel Core™2 Quad CPU Q9650 @3.00GHZ (4 CPUs) Memory: 16384MB Processing results per machine: The applications were executed seven times with the averages being displayed below. Machine Text Records Invoices Generated Converted Per Minute Per Minute Server (1) 650 12 Notebook 980 17 Desktop 2,100 45 (1) The server is dedicated to execution of this application; no additional applications are being executed. Question: Why is the server performance so poor? What can be done to improve the speed of the server?

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• Suggestions for splitting server roles amongst Hyper-V virtual servers / RAID6 or RAID10? / AppAssure

  - by Anon

  We have 2 Hyper-V hosts at present running 1 virtual server that was converted from a physical box running all roles. My plan is to split the roles over various virtual machines, upgrading to the latest software versions as I go, and use the backup server as a standby in case the main server fails. AppAssure backup software has a feature called Virtual Standby, so the VHD's can be ready to be fired up on the backup server if necessary. Off-site backups will be done via external USB drive for now. I'm just seeking some input/suggestions into how I'm planning to split the roles out amongst various virtual servers. Also, I'm curious how to setup the storage on the servers. We do not have any NAS's, SAN'S or any budget for this. What would the best RAID level be to use? I'm thinking either RAID6 (which is currently used) however I'm concerned about the write speeds, or RAID10 but again I'm worried that I can only lose 1 drive (from the same mirror) as opposed to any 2 with RAID6. I realise I have a hot swap for this, but what if a further drive fails during a rebuild? Is the write penalty of RAID6 worth the extra reliability over RAID10? Or will it be too slow with all the roles I am planning, therefore RAID10 is my only real option? The reason for the needed redundancy is I am the only technician and I'm not always on-site. Options I've considered: 1) 5 drives in RAID6 set, 200gb for host OS, rest for VM storage. 1 drive for hot swap - this is how it is currently setup 2) 4 drives in RAID10 set, 200gb for host OS, rest for VM storage. 2 drives for hot swap 3) 4 drives in RAID10 set for VM storage, 2 drives in RAID1 set for host OS. No drives for hot swap - While this is probably the best option with the amount of drives I have, I don't like the idea of having no hot swap 4) 3 drives in RAID6 set for VM storage, 2 drives in RAID1 set for host OS. 1 drive for hot swap All options give us enough storage capacity for our files, etc. We don't have any budget for extra drives or extra hot swap HD chassis for the servers. We have about 70 clients and about 150 users. MAIN SERVER Intel Xeon 5520 @ 2.27 GHz (2 processors) 16GB RAM 6 x 1TB Seagate Barracuda ES.2 Enterprise SATA drives Intel SRCSATAWB RAID controller Virtual machine workload using Hyper-V on Windows Server 2008 R2: DC01 - Active Directory Domain Controller / DNS server / Global catalog - 1GB RAM DC02 - Active Directory Domain Controller / DNS server / Global catalog - 1GB RAM Member Server - DHCP server, File server, Print server - 1GB RAM SCCM Member Server - 4GB RAM Third Party Software Member Server - A/V server, Ticketing software, etc - 4GB RAM Exchange 2007 - 4GB RAM - however we are probably migrating to a hosted solution, therefore freeing up resources BACKUP SERVER Intel Xeon E5410 @ 2.33GHz (2 processors) 16GB RAM 6 x 2TB WD RE4 SATA drives Intel SRCSASRB RAID controller Virtual machine workload using Hyper-V on Windows Server 2008 R2: AppAssure backup software - 8GB RAM

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• Linux filesystem with inodes close on the disk

  - by pts

  I'd like to make the ls -laR /media/myfs on Linux as fast as possible. I'll have 1 million files on the filesystem, 2TB of total file size, and some directories containing as much as 10000 files. Which filesystem should I use and how should I configure it? As far as I understand, the reason why ls -laR is slow because it has to stat(2) each inode (i.e. 1 million stat(2)s), and since inodes are distributed randomly on the disk, each stat(2) needs one disk seek. Here are some solutions I had in mind, none of which I am satisfied with: Create the filesystem on an SSD, because the seek operations on SSDs are fast. This wouldn't work, because a 2TB SSD doesn't exist, or it's prohibitively expensive. Create a filesystem which spans on two block devices: an SSD and a disk; the disk contains file data, and the SSD contains all the metadata (including directory entries, inodes and POSIX extended attributes). Is there a filesystem which supports this? Would it survive a system crash (power outage)? Use find /media/myfs on ext2, ext3 or ext4, instead of ls -laR /media/myfs, because the former can the advantage of the d_type field (see in the getdents(2) man page), so it doesn't have to stat. Unfortunately, this doesn't meet my requirements, because I need all file sizes as well, which find /media/myfs doesn't print. Use a filesystem, such as VFAT, which stores inodes in the directory entries. I'd love this one, but VFAT is not reliable and flexible enough for me, and I don't know of any other filesystem which does that. Do you? Of course, storing inodes in the directory entries wouldn't work for files with a link count more than 1, but that's not a problem since I have only a few dozen such files in my use case. Adjust some settings in /proc or sysctl so that inodes are locked to system memory forever. This would not speed up the first ls -laR /media/myfs, but it would make all subsequent invocations amazingly fast. How can I do this? I don't like this idea, because it doesn't speed up the first invocation, which currently takes 30 minutes. Also I'd like to lock the POSIX extended attributes in memory as well. What do I have to do for that? Use a filesystem which has an online defragmentation tool, which can be instructed to relocate inodes to the the beginning of the block device. Once the relocation is done, I can run dd if=/dev/sdb of=/dev/null bs=1M count=256 to get the beginning of the block device fetched to the kernel in-memory cache without seeking, and then the stat(2) operations would be fast, because they read from the cache. Is there a way to lock those inodes and/or blocks into memory once they have been read? Which filesystem has such a defragmentation tool?

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• Getting an boot error when starting computer

  - by Rob Avery IV

  I was in the middle of watching a movie on Netflix, then suddenly everything started crashing. First, explorer.exe closed down, then Google chrome. I had multiple things running in the background (Steam, Raptr, etc.). Individuality, each of those apps closed down also. When they did, a small dialog box popped up for each of them, one at a time, saying that it was missing a file, it couldn't run anymore, or something similar to that. It also had some jumbled up "code" with numbers and letters that I couldn't read. Ever since then, everytime I turn my computer on, it will run for a few seconds and give this error "Reboot and select proper boot device or insert boot media in selected boot device and press a key_". No matter how many times I try to reboot it, it always gives me the same error. A day later after this happened I was able to start the computer, but before it booted, it told me that I didn't shut down the computer properly and asked how I wanted to run the OS (Run Windows in Safety Mode, Run Windows Normally, etc.). Once I logged, everything went SUPER slow and everything crashed almost instantly. The only thing I opened was Microsoft Security Essentials and only got in about two clicks before it was "Not Responding". Then, after that the whole computer froze and I had to restart it. Now, it's back to saying what it originally said, "Reboot and select proper boot device or insert boot media in selected boot device and press a key_". I built this PC back in February 2012. Here are the specs: OS: Windows 7 Ultimate CPU: AMD 8-core GPU: Nvidia GTX Force 560 Ti RAM: 16GB Hard Drive: Hitachi Deskstar 750GB I'm usually very good taking care of my PC. I don't download anything that's not from a trusted site or source. I don't open up any spam email or such or go to any harmful websites like porn or stream movies. I am very clean with the things I do with my PC and don't do many DIFFERENT things with it. I use it pretty often especially for video games and doing homework in Eclipse. Also, good to note that I don't have any Norton or antisoftware installed. I have Microsoft Security Essentials installed but never did a scan. Thanks!

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• Secure, efficient, version-preserving, filename-hiding backup implemented in this way?

  - by barrycarter

  I tried writing a "perfect" backup program (below), but ran into problems (also below). Is there an efficient/working version of this?: Assumptions: you're backing up from 'local', which you own and has limited disk space to 'remote', which has infinite disk space and belongs to someone else, so you need encryption. Network bandwidth is finite. 'local' keeps a db of backed-up files w/ this data for each file: filename, including full path file's last modified time (mtime) sha1sum of file's unencrypted contents sha1sum of file's encrypted contents Given a list of files to backup (some perhaps already backed up), the program runs 'find' and gets the full path/mtime for each file (this is fairly efficient; conversely, computing the sha1sum of each file would NOT be efficient) The program discards files whose filename and mtime are in 'local' db. The program now computes the sha1sum of the (unencrypted contents of each remaining file. If the sha1sum matches one in 'local' db, we create a special entry in 'local' db that points this file/mtime to the file/mtime of the existing entry. Effectively, we're saying "we have a backup of this file's contents, but under another filename, so no need to back it up again". For each remaining file, we encrypt the file, take the sha1sum of the encrypted file's contents, rsync the file to its sha1sum. Example: if the file's encrypted sha1sum was da39a3ee5e6b4b0d3255bfef95601890afd80709, we'd rsync it to /some/path/da/39/a3/da39a3ee5e6b4b0d3255bfef95601890afd80709 on 'remote'. Once the step above succeeds, we add the file to the 'local' db. Note that we efficiently avoid computing sha1sums and encrypting unless absolutely necessary. Note: I don't specify encryption method: this would be user's choice. The problems: We must encrypt and backup 'local' db regularly. However, 'local' db grows quickly and rsync'ing encrypted files is inefficient, since a small change in 'local' db means a big change in the encrypted version of 'local' db. We create a file on 'remote' for each file on 'local', which is ugly and excessive. We query 'local' db frequently. Even w/ indexes, these queries are slow, since we're often making one query for each file. Would be nice to speed this up by batching queries or something. Probably other problems that I've now forgotten.

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• Unable to burn Windows ISO from Fedora

  - by user331947

  First of all, English is not my native tongue, so apologies for any mistakes. My computer recently started prompting that it can't launch Windows successfully. So I just choose start Windows normally. Then, I found that the startup freezes at the Windows screen (before the login prompt). I have tried rebooting several times and get the same results. So I just gave up. After few days, I tried to boot up my laptop again. This time it got to the desktop, but it's extremely slow and the icons on my Desktop don't show up. I decided to format the Windows partition and reinstall a new one. (It is usually faster that way since I kept my 400GB+ data on aother partition and programs and the rest in the same partition as Windows). The thing is I get the Windows disc at the moment (Traveling aboard). But I have a Windows 7 disc image on my hard disk. So, I downloaded Ubuntu 14.04 LTS, made a Live USB, and then try to burn the image from Ubuntu. But the program just freezes and I don't know why. I tried several times and it's still the same. So I tried using Fedora instead, just to see if it will work. The Disk Image Writer report something like this. Error unmounting /dev/dm-0: Command-line `umount "/dev/dm-0"' exited with non-zero exit status 32: umount: /: target is busy (In some cases useful info about processes that use the device is found by lsof(8) or fuser(1).) (udisks-error-quark, 14) Also, I tried installing linux on the windows partition. The installation program freezes (both Ubuntu and Fedora). So, I thought that maybe something are wrong with my hard disk. I seek the solution on the internet and found that gparted can be used to format a partition. And it also froze at "Searching /dev/sda/ partition ...". I'm using Lenovo Y570. Spec below. http://www.notebookreview.com/notebookreview/lenovo-ideapad-y570-review-a-lenovo-bestseller/3/ Can anyone suggest a next step in diagnosing and fixing this problem? Thanks in advance.

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• Automating silent software deployments on Solaris 10

  - by datSilencer

  Hello everyone. Essentially, the question I'd like to ask is related to the automation of software package deployments on Solaris 10. Specifically, I have a set of software components in tar files that run as daemon processes after being extracted and configured in the host environment. Pretty much like any server side software package out there, I need to ensure that a list of prerequisites are met before extracting and running the software. For example: Checking that certain users exists, and they are associated with one or many user groups. If not, then create them and their group associations. Checking that target application folders exist and if not, then create them with preconfigured path values defined when the package was assembled. Checking that such folders have the appropriate access control level and ownership for a certain user. If not, then set them. Checking that a set of environment variables are defined in /etc/profile, pointed to predefined path locations, added to the general $PATH environment variable, and finally exported into the user's environment. Other files include /etc/services and /etc/system. Obviously, doing this for many boxes (the goal in question) by hand can be slow and error prone. I believe a better alternative is to somehow automate this process. So far I have thought about the following options, and discarded them for one reason or another. 1) Traditional shell scripts. I've only troubleshooted these before, and I don't really have much experience with them. These would be my last resort. 2) Python scripts using the pexpect library for analyzing system command output. This was my initial choice since the target Solaris environments have it installed. However, I want to make sure that I'm not reinveting the wheel again :P. 3) Ant or Gradle scripts. They may be an option since the boxes also have java 1.5 enabled, and the fileset abstractions can be very useful. However, they may fall short when dealing with user and folder permissions checking/setting. It seems obvious to me that I'm not the first person in this situation, but I don't seem to find a utility framework geared towards this purpose. Please let me know if there's a better way to accomplish this. I thank you for your time and help.

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• Suspected network performance issue on VirtualBox Ubuntu guest on Win7 host

  - by Adam

  I set up Ubuntu 12.04 in VirtualBox on the Win7 machine I was allocated on my new project. I am running Java, Eclipse, Tomcat to develop a large data-intensive application and I noticed that this application runs at half the speed of my colleague's identical machine, where he runs it all under Windows. I think I have narrowed down the performance issue to the network, after comparing and equalising all the Java VM settings with my colleague. Is there a ping test I can do or some other network diagnostic test to flag up any problems? To give some background, the network performance is confusing. Running a network speed test to my colleague's machine with iperf shows speeds of 6 Mb/s from my Ubuntu guest, and 90 Mb/s from the win7 host. Large downloads, e.g. the Java SDK, come down at about 1.2 MB/s on both the guest and the host. Pings are sub-1ms on the host, but 1.5ms on the guest. I also did a broadband speed test, and got 10Mb/s download speed on both, but the host has an upload speed of 10Mb/s but the guest only uploads at 3Mb/s. I've been trying to diagnose any MTU problems with ping -M do to identify any kind of packet fragmentation problem but it's progressing very slow because I don't have much experience in this area. From what I read on other people's networking issues with VB and Linux guests on Win7 hosts, I should be able to get the speed on the guest up to the same level as the host. I installed a fresh VM with Ubuntu again to see if I'd foobar'd it somehow, but I'm getting the same readings with iperf on the virgin installation. My setup is: Adapter 1: Intel PRO/1000 MT Desktop (NAT) Adapter 2: ditto (host-only adapter) eth0 Link encap:Ethernet HWaddr 08:00:27:0b:76:bf inet addr:10.0.2.15 Bcast:10.0.2.255 Mask:255.255.255.0 inet6 addr: fe80::a00:27ff:fe0b:76bf/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:86236 errors:0 dropped:0 overruns:0 frame:0 TX packets:49369 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:69163946 (69.1 MB) TX bytes:3530535 (3.5 MB) eth2 Link encap:Ethernet HWaddr 08:00:27:a3:26:b8 inet addr:192.168.56.101 Bcast:192.168.56.255 Mask:255.255.255.0 inet6 addr: fe80::a00:27ff:fea3:26b8/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:59 errors:0 dropped:0 overruns:0 frame:0 TX packets:57 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:9148 (9.1 KB) TX bytes:7648 (7.6 KB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:701 errors:0 dropped:0 overruns:0 frame:0 TX packets:701 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:66321 (66.3 KB) TX bytes:66321 (66.3 KB)

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• Unable to boot from LiveCD/USB and even Super Grub Disk!

  - by Reuben L.

  Hi all, I'm in a fix. Basically this morning, I decided to format my Win7 as it was getting really slow and I did so with no problems. I also have a Linux Mint OS on dual boot. Since I was springcleaning my windows partition, I decided it was a good idea to do the same to my linux partition. I downloaded the latest version of Linux Mint (Julia) and burned the LiveCD. Now here is where the problem lies, when I restarted Windows and chose to boot from the LiveCD, it didn't work. No joke. There was just a little underscore blinking for a long time before it went back to GRUB which prompted me to select an OS to boot. However, when I went into my old Linux Mint OS and restarted the machine, the LiveCD worked... to a certain extent. It would load and look as though it was ready to install Linux Mint 10 but the moment it got to the option screen, the whole screen turned into a checkered and jumbled mess. At this point I thought it was the LiveCD or the .iso file. I had an Ubuntu LiveUSB for recovery purposes and I tried that. The exact same thing happened. Can't boot the LiveUSB if I restarted from Windows, but works when I reboot from Linux. BUT still the same checkered screen that doesnt respond. Did a bit of googling and reckoned it might be something wrong with my GRUB. Did some updating and didnt make a difference. Then I tried the Super Grub Disk and STUPIDLY uninstalled GRUB. (Note that booting to SGD had the exact same problem - can't be done if I rebooted from Windows). Now I can't access my Linux Mint 9 cos the the bootup screen (mbr) only has Windows 7 as an option. Remember me mentioning that I can't boot from any CD/USB/recovery CD when I reboot from Windows? And now that I can't access Linux, there's no way for me to do any form of recovery! I've tried using the command prompt utility at startup recovery but to no avail. Anyone can help me with this?

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• How do I (robustly) remotely execute tasks on Windows workstations in a domain?

  - by Zac B

  I'm not even sure if "robustly" is a word. Anyway. Context: We have a few hundred Windows 7 workstations on a LAN. We use AD/GPO management pretty heavily, but there are a lot of periodic and/or manual maintenance tasks we need to do that can't be done via GPO/scheduled task. For example, say I want to execute program X (which runs silently, in the background, and doesn't bother the user) on workstation Y, or say I want to execute task A on a workstation group B either on a schedule or on demand. Kicking the users off of their computers to do this (i.e. using RDP) is a no-no, and doesn't work on groups anyway. Question: What's the best way to do this that is robust enough that, after setup, I could give it to beginner support people (read: people who are phobic of the command line, and get confused with GUI interfaces more complicated than Firefox)? I'm a competent programmer, and, if there is a robust set of tools or framework out there for this type of task, I'd consider hacking something together myself if it didn't take too long. If there's some combination of tools or techniques that others use to make remote-workstation-administration doable by beginners, I have yet to find it. For those who care about the "why": I'm midlevel IT, and was told to implement a remote management solution that allows arbitrary/scheduled remote execution, with confirmation that programs actually ran remotely, and the ability to view what they returned. "Why?" I asked, "Can't I just use PsExec and the task scheduler on a dispatcher machine?" "No," I was told, "'Joe' the second-week tech is going to be in charge of this one, and he needs something simple with a GUI." What I've tried: I've played with making a bunch of one-clickable "transfer files to remote computer and run them with PsExec" batch/VB scrips, but those tend to break down and don't easily support running on customizable groups. I've played a little bit with the Windows version of Puppet, but it doesn't support arbitrary-time remote execution (it's ability to group computers into a tree/node structure is really nice though). I've used an older version of Altiris, and, while it does a lot of what I want, it's interface is awful, it's slow, crashes a lot, and is probably too expensive for management. SwiftWater's DMS solution does some of what I want, but it's very underdeveloped, closed-source (not a deal breaker but not ideal), and I get the impression that support and reliability are lacking.

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• Multiple OS's and GRUB chainloading

  - by Kent

  Hi, I want to have multiple OS installations and I have been advised that chain loading using GRUB is a good way to handle this. I have looked at tutorials on the web but I still have some questions before I can start. I want: Windows XP: 20 GB. For running some school stuff and a game which does not work through WINE. Xubuntu 9.04: 85 GB. My main OS. Another Linux distribution: 15 GB . For experimenting and trying Linux distributions out. I will: Wipe and install various distributions quite often on the 15 Use dd to make a copy of my Windows partition after installing it and getting things to work as I like. My experience is that Windows needs to be re-installed maybe once per year to not get bloated and slow. I have been told: To use GRUB chain loading. It will make it easier when kernel upgrades are made in the Linux distributions, as they modify the GRUB boot-menu. To my understanding I need to: (I might very well be mistaken) Install Windows first. Then install Xubuntu and let it write over the MBR with GRUB (I guess this is the default). Get the GRUB on the MBR start Windows XP if I want to (it's done by default), start Xubuntu using the kernel of my choice or defer execution to the boot sector of my other Linux distribution. The actual chain loading will only occur when I want to start my experimental install of Linux. I wonder: Is step 3 above correct and a good way to handle this? Is it also a good way to use chain-loading for both Xubuntu and my experimental Linux installation? How do I get a Linux distribution to install the boot loader it comes with to the boot sector of its partition and not to the MBR? If I can't get it to not touch the MBR. Then I could make a backup of the MBR using dd and then write it back after installing my experimental Linux installation. But then, how would I get the boot loader (lets say GRUB) into the boot sector of the experimental Linux installation? How would it work if said Linux installation gets a new kernel update and needs to update the GRUB menu?

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• Triple (3) Monitors under Linux

  - by widgisoft

  I have a 3 monitor setup (each 1680x1050) via an Nvidia NVS440 (2 GPUs, 2 outputs per GPU totalling 4 outputs); this works fine under Windows XP,7 but caused considerable headaches under Linux (Ubuntu 9.04). I had previously used an XFX 9600GT and the onboard XFX 9300GS to produce the same result but the card was noisy and power hungry and I was hoping that there was some magical switch in the NVS4400 that got rid of this annoying problem - turns out the NVS440 is just 2 cards on one physical PCB :-p (I searched the net high and low for people using this card under Linux but found nothing, if anything the card uses less power and is fan less so I was to benefit from it either way) Anyway, using either set up there were 5 solutions available: Have 3 separate X instances, all un joined Have 3 separate X instances, adjoined by Xinerama Have 2 separate X instances - One using twin-view, both adjoined by Xinerama Have 2 separate X instances - One using twin-view but no Xinerama Have a single Twin-view setup and leave the 3rd screen unplugged :-p The 4rd option, using 2 separate X instances and twinview (but no xinerama) was the best balance in terms of performance and usability but caused 2 really annoying issues You couldn't control (without altering the shortcuts) which screen an application opened onto - and once it was opened you couldn't move it to another screen without opening up terminal and forcing it to move Nvidia's overriding or falsifying of Xinerama breaks and the 2 screens joined by Twin view behave like a single huge screen causing popups to open in the middle of both screens and maximising of windows stretches to the width of the first 2 screens Firefox can only run one instance as the same user so having multiple firefox windows requires at least 2 users The second option "feels" like the right option, but OpenGL is basically disabled and playing any sort of game or even running anything graphical causes a huge performance drop and instability - even trying to run a basic emulator for gba or gens just causes the system to fall over. It works just enough to stare at your desktop and do nothing but as soon as you start doing some work - opening windows, dragging things around - running multiple copies of firefox it just really feels slow. The last open, only going dual screen works perfectly and everything performs as required, full GPU acceleration - two logical screen spaces - perfect, just make it work across GPUs like windows! :-p Anyway, I know RandR was supposed to pick up the slack when it would introduced GPU objects of sorts to allow multiple GPUs to be stitched together to create one huge desktop at a much deeper layer than Xinerama. I was wondering if this has now been fixed (I noticed X server 1.7 is out) and whether anyone has got it running successfully? Again, my requirements are: One huge desktop to drag any window across Maximising of windows to each screen (as XP does) Running fullscreen apps on the primary screen and disabling the mouse from moving onto the others or on all 3 stretched Finally as a side note; I am aware of the Matrox triple (and dual) head splitter but even the price they go for on eBay is more than I can afford atm, my argument: I shouldn't have to buy extra hardware to get something to work on Linux when it's something that's existed in the windows world for a long time (can you tell I don't get on with X :-p); If I had the cash I'd have bought the latest version of this box already (the new version finally supports large resolutions as the displays I have 1680x1050 each).

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• How to disable or tune filesystem cache sharing for OpenVZ?

  - by gertvdijk

  For OpenVZ, an example of container-based virtualization, it seems that host and all guests are sharing the filesystem cache. This sounds paradoxical when talking about virtualization, but this is actually a feature of OpenVZ. It makes sense too. Because only one kernel is running, it's possible to benefit from sharing the same pages of filesystem cache in memory. And while it sounds beneficial, I think a set up here actually suffers in performance from it. Here's why I think why: my machines aren't actually sharing any files on disk so I can't benefit from this feature in OpenVZ. Several OpenVZ machines are running MySQL with MyISAM tables. MyISAM relies on the system's filesystem cache for caching of data files, unlike InnoDB's buffer pool. Also some virtual machines are known to do heavy and large I/O operations on the same filesystem in the host. For example, when running cat *.MYD > /dev/null on some large database in one machine, I saw the filesystem cache lowering in another, monitored by htop. This essentially flushes all the useful filesystem cache in guests (FIFO) and so it flushes the MySQL caches in the guests. Now users are complaining that MySQL is very slow. And it is. Some simple SELECT queries take several seconds on times disk I/O is heavily used by other machines. So, simply put: Is there a way to avoid filesystem cache being wiped out by other virtual machines in container-based virtualization? Some thoughts: Choosing algorithm for flushing filesystem cache in the kernel. (possible? how?) Reserving a certain amount of pages for a single VM. (seems no option for filesystem cache type of pages that reading man vzctl) Will running MySQL on another filesystem get me anywhere? If not, I think my alternatives are: Use KVM for MySQL-MyISAM running VMs. KVM actually assigns memory to the VM and does not allow swapping out caches unless using a balloon driver. Move to InnoDB and tune the buffer pools, dirty pages, etc. This is now considered to be 'nice to have' on the long-term as not everyone responsible for administration of the system understands InnoDB. more suggestions welcome. System software: Proxmox (now 1.9, could be upgraded to 2.x). One big LV assigned for the VMs.

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• Alternative Windows Offline Files + Windows Backup + Previous Version Setup

  - by Herson

  Currently our documents are all hosted in a Windows 7 box. Users can access the files using Windows share and the documents are available offline (windows 7 feature). The documents are being backed up daily by Windows 7 backup and restore utility. Users can access previous versions of the file (from the backups) using Windows Explorer "previous versions" feature. This setup is currently working well, except for the following: We would prefer to have access to hourly versions of the file, not daily. The previous version mechanism is tied up to the backup mechanism. Windows 7 performs a full backup every week and incremental backup everyday. The previous versions of a file is actually what are the available in the backups. If you 20GB documents and want to maintain at least three(3) year history, you will use at minimum 3 years * 52 weeks * 20GB or about 3TB even if there are few changes in the documents. Its pretty inefficient use of space. Looking up previous versions of a file is very slow (tens of minutes). This is probably related to the previous issue - Windows has to traverse its all of its backups. I am considering using SVN + autocommit/autoupdate tortoisesvn. It will have the following advantages: Backups are easy and will also backup the whole history of each documents. (Just backup the repository). Creating previous versions can be frequent. I think svn commit / update can be done every two minutes or so. Users can sync over the net. However, I can see the following issues: More conflicts than the original setup because both multiple users can now edit the same file even both are online, i.e. can connect to the SVN repo. The users can off course lock the file first before editing, but that would mean they have to adjust. Delay on propagation of file changes. On windows 7 file sharing, changes made by one online user will be instantaneously available to other online users. With the SVN setup, changes will only be propagated when the users execute the svn add/commit/update sequence. Delay will be probably a few minutes. This workflow will no longer work: "Hi, I just edited document X, can you have a quick look?" I would like to ask the opinion of the community for alternative setups, or improvements on the above setups to work out the kinks.

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• Wifi randomly drops on Windows 8 laptop

  - by JosiahS

  First of all, I did a lot of research on this problem, and I wasn't able to come to any helpful conclusion. I've finally decided that I need advice from those who might know where to look. So don't let me down. :P I used to have an older Windows 7 laptop, which worked great for basic office and web browsing. However, I wanted something that would play actual modern games. So I recently bought a Sager NP8235 with the Intel Wireless-AC 7260 wifi card, and installed Windows 8 Pro on it. And ever since, I've been having problems with the wifi. Generally, what happens is if I leave the laptop on but inactive for an extended amount of time (I've estimated it around an hour to two), the wifi will start dropping randomly. If I happened to have a download going at the time, it usually causes the download to fail. Or, if I put the laptop to sleep overnight, the next morning I usually have to restart the computer because the wifi device apparently stops working (it literally won't turn on). Also, and most frustrating, whenever I'm on a video chat (like Skype), after about ten minutes, the connection will start lagging like crazy, until it forces Skype to end the call. After that, I usually have to disable and reenable the wifi to get it working again. I know it isn't our internet, because all the other computers in our house (~8) don't have any issues. Even the old Windows 7 laptop (connected also over wifi) works just fine, scoring the normal ~3Mbps average on speedtest.net (yes, I know our internet is slow, we live out in the country). Additionally, when I connect the Sager directly to the router via ethernet, the internet instantly starts working just great. Like I said, I've done a lot of googling to figure out what's going on, and I haven't been able to find anything that worked for me. Is it Windows 8 conflicting with the Wifi drivers? As of this writing, I have the Intel drivers v16.1.5.2 installed (without the extra Intel software). Or is it our router? It's a TP-Link TL-WR841ND, set to the default settings. The Sager is currently being assigned to a static IP, if that makes any difference. And yet, the old windows 7 laptop has a much more stable connection than the Sager. Anyone have any ideas? At this point, I'd appreciate even knowing what the problem is.

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• I can't connect to mysql on a remote server

  - by eisaacson

  I'm trying to connect from an Ubuntu server to a RHEL6 server using mysql. I've tried telneting into the server as well as trying to connect with mysql. I've tried commenting out the bind-address but didn't have any success with that either. I don't get an error code or anything with telnet. It just fails after a minute or so. With mysql, I get this error code ERROR 2003 (HY000): Can't connect to MySQL server on 'SERVER_IP' (111). "SERVER_IP" is of course a placeholder where actual error gives that actual IP. I've included my my.cnf as well as well as my iptables from the destination server. On Destination Server... my.cnf: [mysqld] bind-address=0.0.0.0 tmp_table_size=512M max_heap_table_size=512M sort_buffer_size=32M read_buffer_size=128K read_rnd_buffer_size=256K table_cache=2048 key_buffer_size=512M thread_cache_size=50 query_cache_type=1 query_cache_size=256M query_cache_limit=24M #query_alloc_block_size=128 #query_cache_min_res_unit=128 innodb_log_buffer_size=16M innodb_flush_log_at_trx_commit=2 innodb_file_per_table innodb_log_files_in_group=2 innodb_buffer_pool_size=32G innodb_log_file_size=512M innodb_additional_mem_pool_size=20M join_buffer_size=128K max_allowed_packet=100M max_connections=256 wait_timeout=28800 interactive_timeout=3600 # modify isolation method for faster inserting. # Do not uncomment the line below unless you understand what this does. # transaction-isolation = READ-COMMITTED # do not reverse lookup clients skip-name-resolve #long_query_time=6 #log_slow_queries=/var/log/mysqld-slow.log #log_queries_not_using_indexes=On #log_slow_admin_statements=On datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock user=mysql # Disabling symbolic-links is recommended to prevent assorted security risks symbolic-links=0 #Added by Magento ECG long_query_time=1 slow_query_log [mysqld_safe] log-error=/var/log/mysqld.log pid-file=/var/run/mysqld/mysqld.pid iptables: :INPUT ACCEPT [0:0] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [0:0] -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT -A INPUT -p icmp -j ACCEPT -A INPUT -i lo -j ACCEPT -A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT -A INPUT -m state --state NEW -m tcp -p tcp --dport 3306 -j ACCEPT -A INPUT -m state --state NEW -m tcp -p tcp --dport 225 -j ACCEPT -A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT -A INPUT -m state --state NEW -m tcp -p tcp -i eth1 --dport 11211 -j ACCEPT -A INPUT -j REJECT --reject-with icmp-host-prohibited -A FORWARD -j REJECT --reject-with icmp-host-prohibited COMMIT sudo netstat -ntpl Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN - tcp 0 0 0.0.0.0:11211 0.0.0.0:* LISTEN - tcp 0 0 0.0.0.0:2123 0.0.0.0:* LISTEN - tcp 0 0 0.0.0.0:1581 0.0.0.0:* LISTEN - tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN - tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN - tcp 0 0 :::11211 :::* LISTEN - tcp 0 0 :::22 :::* LISTEN - tcp 0 0 :::225 :::* LISTEN -

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• MongoDB and datasets that don't fit in RAM no matter how hard you shove

  - by sysadmin1138

  This is very system dependent, but chances are near certain we'll scale past some arbitrary cliff and get into Real Trouble. I'm curious what kind of rules-of-thumb exist for a good RAM to Disk-space ratio. We're planning our next round of systems, and need to make some choices regarding RAM, SSDs, and how much of each the new nodes will get. But now for some performance details! During normal workflow of a single project-run, MongoDB is hit with a very high percentage of writes (70-80%). Once the second stage of the processing pipeline hits, it's extremely high read as it needs to deduplicate records identified in the first half of processing. This is the workflow for which "keep your working set in RAM" is made for, and we're designing around that assumption. The entire dataset is continually hit with random queries from end-user derived sources; though the frequency is irregular, the size is usually pretty small (groups of 10 documents). Since this is user-facing, the replies need to be under the "bored-now" threshold of 3 seconds. This access pattern is much less likely to be in cache, so will be very likely to incur disk hits. A secondary processing workflow is high read of previous processing runs that may be days, weeks, or even months old, and is run infrequently but still needs to be zippy. Up to 100% of the documents in the previous processing run will be accessed. No amount of cache-warming can help with this, I suspect. Finished document sizes vary widely, but the median size is about 8K. The high-read portion of the normal project processing strongly suggests the use of Replicas to help distribute the Read traffic. I have read elsewhere that a 1:10 RAM-GB to HD-GB is a good rule-of-thumb for slow disks, As we are seriously considering using much faster SSDs, I'd like to know if there is a similar rule of thumb for fast disks. I know we're using Mongo in a way where cache-everything really isn't going to fly, which is why I'm looking at ways to engineer a system that can survive such usage. The entire dataset will likely be most of a TB within half a year and keep growing.

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• SQLS Timeouts - High Reads in Profiler

  - by lb01

  I've audited a SQLS2008 server with Profiler for one day.. the overhead didn't seem to trouble this new client my company has. They are using a legacy VB6 application as a front-end. They're experiencing timeouts once SQLS RAM usage is high. The server is currently running x64 sqls2008 on a VM with nearly 9 GB of RAM. SQL Server's 'max server memory option' is currently set to 6GB. I've put the results of the trace in a table and queried them using this query. SELECT TextData, ApplicationName, Reads FROM [TraceWednesday] WHERE textdata is not null and EventClass = 12 GROUP BY TextData, ApplicationName, Reads ORDER BY Reads DESC As I expected, some values are very high. Top Reads, in pages. 2504188 1965910 1445636 1252433 1239108 1210153 1088580 1072725 Am I correct in thinking that the top one (2504188 pages) is 20033504 KB, which then is roughly ~20'000 MB, 20GB? These queries are often executed and can take quite some time to run. Eventually RAM is used up because of the cache fattening, and timeouts occur once SQL cannot 'splash' pages in the buffer pool as much. Costs go up. Am I correct in my understanding? I've read that I should tune the associated T-SQL and create appropriate indices. Obviously cutting down the I/O would make SQL Server use less RAM. OR, maybe it might just slow down the process of chewing up the whole RAM. If a lot less pages are read, maybe it'll all run much better even when usage is high? (less time swapping, etc.) Currently, our only option is to restart SQL once a week when RAM usage is high, suddenly the timeouts disappear. SQL breathes again. I'm sure lots of DBAs have been in this situation.. I'm asking before I start digging out all of the bad T-SQL and put indices here and there, is there is something else I can do? Any advice except from what I know (not much yet..) Much appreciated. Leo.

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• Troubleshooting Network Speeds -- The Age Old Inquiry

  - by John K

  I'm looking for help with what I'm sure is an age old question. I've found myself in a situation of yearning to understand network throughput more clearly, but I can't seem to find information that makes it "click" We have a few servers distributed geographically, running various versions of Windows. Assuming we always use one host (a desktop) as the source, when copying data from that host to other servers across the country, we see a high variance in speed. In some cases, we can copy data at 12MB/s consistently, in others, we're seeing 0.8 MB/s. It should be noted, after testing 8 destinations, we always seem to be at either 0.6-0.8MB/s or 11-12 MB/s. In the building we're primarily concerned with, we have an OC-3 connection to our ISP. I know there are a lot of variables at play, but I guess I was hoping the experts here could help answer a few basic questions to help bolster my understanding. 1.) For older machines, running Windows XP, server 2003, etc, with a 100Mbps Ethernet card and 72 ms typical latency, does 0.8 MB/s sound at all reasonable? Or do you think that slow enough to indicate a problem? 2.) The classic "mathematical fastest speed" of "throughput = TCP window / latency," is, in our case, calculated to 0.8 MB/s (64Kb / 72 ms). My understanding is that is an upper bounds; that you would never expect to reach (due to overhead) let alone surpass that speed. In some cases though, we're seeing speeds of 12.3 MB/s. There are Steelhead accelerators scattered around the network, could those account for such a higher transfer rate? 3.) It's been suggested that the use SMB vs. SMB2 could explain the differences in speed. Indeed, as expected, packet captures show both being used depending on the OS versions in play, as we would expect. I understand what determines SMB2 being used or not, but I'm curious to know what kind of performance gain you can expect with SMB2. My problem simply seems to be a lack of experience, and more importantly, perspective, in terms of what are and are not reasonable network speeds. Could anyone help impart come context/perspective?

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