Discuss December 2007

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279 participants
374 discussions

weird load values
by J. Potter 06 Dec '07

06 Dec '07

Hi List, I'm stumped by this: load average: 10.65, 594.71, 526.58 We're monitoring load every ~3 minutes. It'll be fine (i.e. something like load average: 2.14, 1.27, 1.03), and then in a single sample, jump to something like the above. This seems to happen once a week or so on a few different servers (all running in a similar application). I've never seen the 1 minute sample spike as high as the 5 or 15 minute samples. Seeing as that last value is a 15 minute period, well, it doesn't seem possible that one can have a 500+ 15 minute sample without having observed a spike in the 5 minute sample at least 5 minutes before. Also, there aren't 500+ processes on these systems -- it's typically around 100 total processes (ps auxw | wc -l). (Is there a way to see the total count of kernel-level threads?) Thoughts? best, Jeff Linux someHostName 2.6.18-8.1.8.el5 #1 SMP Tue Jul 10 06:39:17 EDT 2007 x86_64 x86_64 x86_64 GNU/Linux CentOS release 5 (Final) 09:31:15 up 65 days, 17:45, 2 users, load average: 0.92, 200.91, 371.30

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A few questions about remastering
by Mário Gamito 06 Dec '07

06 Dec '07

Hi, I've searched all over Google, but couldn't find a proper answer to my needs. I've installed CentOS 5.1 only with the packages I need and then made a few of my own. Now, here's what I need: a) To integrate my self-made packages in a remasterized DVD; b) That the install process of the new version skips package choosing, i. e., when it reaches this stage it just installs all the packages of the new version; c) And last, but not the least, how to remasterize the new DVD with the original packages I've installed, plus the ones I've made. Any help would be appreciated. Warm Regards, Mário Gamito

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Filesystem that doesn't store duplicate data
by rsivak＠istandfor.com 06 Dec '07

06 Dec '07

Is there such a filesystem available? It seems like it wouldn't be too hard to implement... Basically do things on a block by block basis. Store md5 of a block in the table, and when writing a new block, check if the md5 already exists and then point the new block to the old block. Since md5 is not guaranteed unique, might need to do a diff between the 2 blocks and if the blocks are indeed different, handle it somehow. When modifying an existing block that has multiple pointers, copy the block and modify the new block. I know I'm oversimplifying things a lot, but something like this could work, no? Would be a great filesystem to store backups on, or things like vmware volumes... Russ Sent from my Verizon Wireless BlackBerry

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Re: [CentOS] Re: SCSI bad block table display
by Brent L. Bates 06 Dec '07

06 Dec '07

Hugh Cruickshank, you are not mistaken. SCSI drives do keep bad block information on the drive. I've also been using this for YEARS on SGI's under IRIX. Under IRIX, the command `fx' is used to partition SCSI drives, exercise them, format them (which is something one never does to SCSI drives), spare out bad blocks, list the bad block table, etc., etc.. -- Brent L. Bates (UNIX Sys. Admin.) M.S. 912 Phone:(757) 865-1400, x204 NASA Langley Research Center FAX:(757) 865-8177 Hampton, Virginia 23681-0001 Email: B.L.BATES(a)larc.nasa.gov http://www.vigyan.com/~blbates/

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Re: [CentOS] Re: are RPMForge and EPEL compatible?
by David Thompson 06 Dec '07

06 Dec '07

Paul Heinlein wrote: > >Tom Lehrer sang it best: > > http://www.youtube.com/watch?v=aIlJ8ZCs4jY I was thinking more along the lines on Mick Jager: http://www.youtube.com/watch?v=4FqGz0z4dI0 Dave Thompson UW-Madison

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Re: Load Balancing
by Rajagopal Swaminathan 06 Dec '07

06 Dec '07

Greetings, First let me thank the gentleman who allayed my fears about CentOS 5.1's "yum update" download size. but all the same it turned out to be in megabytes. not to mention the k3b *roasted* couple of DVD's to uselessness and I am still giving explanations to the stupid ancient,retired, former stupid cretin bean counters masquerading as "managers" and "management Accountants" on. a piddly amount wasted. I found this thread in the GMANE list as I subscribed to this list rather late. Let me propose a solution: Let two nodes run the greatest ever CentOS 5.0 on two nodes. Let two nodes of the cluster run DRBD 0.8 and export block devices in Primary/Primary mode and the GFS be mounted on them. Let the NFS export be a managed service of the Cluster infrastructure from these nodes exporting the NFS on a cluster managed virtual IP as rw. let n (as permitted by the infrastructure) nodes import NFS as client on their nodes. and do the job I am seeing a 3-node cluster exactly that far past fes days and naturally, given the maturity of CentOS 5, do that for, hopefully, ever. In the ,eantime of the replies hopefully the readers will enjoy the solutions proposed by me regards, Rajagopal

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Prevent kernel upgrade unless given dependencies satisfied
by Ross S. W. Walker 06 Dec '07

06 Dec '07

Dear List Members, Is there a way to prevent a kernel from being upgraded unless a list of given dependencies are satisfied? What I am getting at is sometimes updated kernels are available before the upgraded versions of the kernel modules in 'extras' are (ie drbd). If there were a way to list these modules as dependencies that must be satisfied before a kernel upgrade can be performed it would prevent a lot of pain around upgrade management. Thanks, Ross S. W. Walker Information Systems Manager Medallion Financial, Corp. 437 Madison Avenue 38th Floor New York, NY 10022 Tel: (212) 328-2165 Fax: (212) 328-2125 WWW: http://www.medallion.com <http://www.medallion.com/> ______________________________________________________________________ This e-mail, and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, you are hereby notified that any dissemination, distribution or copying of this e-mail, and any attachments thereto, is strictly prohibited. If you have received this e-mail in error, please immediately notify the sender and permanently delete the original and any copy or printout thereof.

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Re: [CentOS] Filesystem that doesn't store duplicate data
by Ross S. W. Walker 06 Dec '07

06 Dec '07

These are all good and valid issues. Thinking about it some more I might just implement it as a system service that scans given disk volumes in the background, keeps a hidden directory where it stores it's state information and hardlinks named after the md5 hash of the files on the volume. If a collission occurs with an existing md5 hash then the new file is unlinked and re-linked to the md5 hash file, if an md5 hash file exists with no secondary links then it is removed. Maybe monitor the journal or use inotify to just get new files and once a week do a full volume scan. This way the file system performs as well as it normally does and as things go forward duplicate files are eliminated (combined). Of course the problem arises of what to do when 1 duplicate is modified, but the other should remain the same... Of course what you said about revisions that differ just a little won't take advantage of this, but it's file level so it only works with whole files, still better then nothing. -Ross -----Original Message----- From: centos-bounces(a)centos.org <centos-bounces(a)centos.org> To: CentOS mailing list <centos(a)centos.org> Sent: Thu Dec 06 08:10:38 2007 Subject: Re: [CentOS] Filesystem that doesn't store duplicate data On Thursday 06 December 2007, Ross S. W. Walker wrote: > How about a FUSE file system (userland, ie NTFS 3G) that layers > on top of any file system that supports hard links That would be easy but I can see a few issues with that approach: 1) On file level rather than block level you're going to be much more inefficient. I for one have gigabytes of revisions of files that have changed a little between each file. 2) You have to write all datablocks to disk and then erase them again if you find a match. That will slow you down and create some weird behavior. I.e. you know the FS shouldn't store duplicate data, yet you can't use cp to copy a 10G file if only 9G are free. If you copy a 8G file, you see the usage increase till only 1G is free, then when your app closes the file, you are going to go back to 9G free... 3) Rather than continuously looking for matches on block level, you have to search for matches on files that can be any size. That is fine if you have a 100K file - but if you have a 100M or larger file, the checksum calculations will take you forever. This means rather than adding a specific, small penalty to every write call, you add a unknown penalty, proportional to file size when closing the file. Also, the fact that most C coders don't check the return code of close doesn't make me happy there... Peter. _______________________________________________ CentOS mailing list CentOS(a)centos.org http://lists.centos.org/mailman/listinfo/centos ______________________________________________________________________ This e-mail, and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, you are hereby notified that any dissemination, distribution or copying of this e-mail, and any attachments thereto, is strictly prohibited. If you have received this e-mail in error, please immediately notify the sender and permanently delete the original and any copy or printout thereof.

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File system cache corruption with CentOS4?
by James Pearson 06 Dec '07

06 Dec '07

Just wondering if anyone else has come across an issue where files cached in memory appear to become 'corrupted' - for example, on one workstation, I've just had the issue: # yum Traceback (most recent call last): File "/usr/bin/yum", line 4, in ? import yum File "__init__.py", line 36, in ? File "config.py", line 34, in ? File "repos.py", line 29, in ? File "repoMDObject.py", line 18, in ? strace'ing the process didn't show up anything obvious However, I ran a simple process that just grabs memory - which has the side effect of 'flushing' caches from memory. After, doing this, yum ran fine ... I've seen this issue quite a few times with various applications and on different machines - and flushing the caches in the way fixes the issue ... OK, it could be a real memory problem, but given the number of times I see this issue, on machines that are fine otherwise, it makes we wonder if it could be a cache issue ... All the machines are running a CentOS4.4 based kernel - (I plan to move to a CentOS4.6 based kernel when it is out). The kernel is not a vanilla CentOS4.4 kernel - it includes a few small non-standard patches - but nothing that touches the VFS layer (AFAIK). The issue occurs on i686 or x86_64 boxes. All machines have at least 4GB of memory. They also use the nVidia binary-only module. Anyone seen issues like this? Thanks James Pearson

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smartd.conf get overridden
by Christian Volker 06 Dec '07

06 Dec '07

Yohoo! I have some issues with the smartd in CentOS5/x64 I edited the /etc/smartd.conf for my needs and restarted the smartd with "service smartd restart". But the start script is overriding my file. I checked it and saw the following lines: ---------------/etc/init.d/smartd------------ case "$1" in start | reload | restart) GEN_CONF="*SMARTD*AUTOGENERATED*" [ ! -f /etc/smartd.conf ] || read DUMMY GEN_CONF DUMMY </etc/smartd.conf \ && [ "$GEN_CONF" == "*SMARTD*AUTOGENERATED*" ] \ && smartd-conf.py 2>/dev/null >/etc/smartd.conf.new-autogenerated \ && mv -f /etc/smartd.conf.new-autogenerated /etc/smartd.conf ;; esac ---------------/etc/init.d/smartd------------ So how can I prevent my file beeeing overriden without editing this script (which will probably get lots the next update)? ------/etc/sysctl/smartmontools--------- # command line options for smartd smartd_opts="-q never" ---------------------------------------- Any ideas? Christian Volker Technical Support Engineer -- Parnell House, Barrack Square, Ballincollig, Co. Cork, Ireland t: + 353 21 466 0019 e: cvolker(a)vmware.com

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Discuss December 2007