Discuss May 2008

discuss@lists.centos.org

268 participants
281 discussions

Yum + priorities plugin question
by jleaver+centos＠reachone.com 07 May '08

07 May '08

Hello all! I've recently started using the priorities plugin as part of my best practices. It's very effective, and prevents nasty things from happening (like atrpms upgrading python and disabling yum.) I'm wondering if there's a simple and elegant way to allow package-name-based exclusions. For example: For my mysql cluster, I'd prefer to have the latest mysql and mysql-server packages which I can get from utterramblings (Thanks Jason!), however, to do so while using the priorities plugin, I'd need to make that repo an equal priority with base, so that it'll upgrade. I've worked around the problem by creating a duplicate repo with the exceptions as an includepkg and a priority equal to that of base, but it seems less than elegant, and I know it results in double the internet traffic for the repo mirror, which is less than friendly. Does anyone know if there's a more elegant way to deal with this issue, or might this be an appropriate feature request for the plugin developer? Sincerely, Jacob Leaver Sr. System Administrator ReachONE Internet

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VSFTPD with LDAP
by Jake 07 May '08

07 May '08

It appears as I have VSFTPD allowing access authenticating to my LDAP server correctly. I did this by configuring my server to authenticate to my LDAP server from the GUI using System -> Administration -> Authentication. However now when I look at /var/log/secure it says authentication failure. How is this possible and how do I correct this? --Thanks, Jake

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centOS xen domU kernel
by David Hláčik 07 May '08

07 May '08

Hi, how can i make actual xen kernel to work under my domU virtual machines? When i will provide as kernel /boot/vmlinuz-2.6.18-53.1.14.el5xen as ramdisk /boot/initrd-2.6.18-53.1.14.el5xen.img , it will not work becouse of error that root device does not exists. And when it is booting it is showing that raid md0 and my logical volumes does not exists - like those on dom0. I believe it is becouse of ram disk. What is the best approach to solve this .. in official way? Can i use same ramdisk as for dom0, how? or should i create a new one for xen ... Thanks in advance!

2 1

File Permissions or Partition Write/Read for everyone
by Victor Padro 07 May '08

07 May '08

Hello all, I am kinda new to Linux, FreeBSD...most Windows user, anyway. I got a little problem here maybe you can help me solve it. I just bought a new 500Gb HDD which i formated using ext3 under Centos 5, my plan was to use it under FreeNAS as another Backup File Disk(It has already like 400gb of data), when I try to access the disk via samba/cifs I just have the read attribute or permission, how can i change the whole partition permission rights to be accessible to write/read for everyone? (I will mantain the security using samba users and groups of course.), or do I have to apply the chmod comand to the main folder? I'm really stuck here. Thank you Victor. P.S. Sorry for my english.

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Re: [CentOS] I need storage server advice
by Ross S. W. Walker 07 May '08

07 May '08

Yes, though slammed hardware RAID a bit. Software RAID has it's place don't get me wrong, it's just knowing when and where. Now the problem I have with your approach under the OP's requirements is the only way to fit that kinda storage over that long a period is with external enclosures and there isn't many systems that have external 4 lane serial storage connectors builtin, so one needs a card that can perform that and if you are shopping for a card to do that then you might as well get one for a few $100 more that has on board RAID. Also if the OP wanted to switch distro's he will not have to worry about losing the RAID configuration or hosing it in the process. -Ross ----- Original Message ----- From: centos-bounces(a)centos.org <centos-bounces(a)centos.org> To: CentOS mailing list <centos(a)centos.org> Sent: Tue May 06 20:39:52 2008 Subject: Re: [CentOS] I need storage server advice The point was, acceptable performance can be had without purchasing a hardware controller. And for archival purposes on a tight budget $500 bucks means one controller for 3 more drives. On Tue, May 6, 2008 at 6:17 PM, John R Pierce <pierce(a)hogranch.com> wrote: Ross S. W. Walker wrote: Take these benchmarks with a grain of salt. and, more importantly, for the thread at hand, this guy wants an ARCHIVE server, where performance is quite secondary, reliablity and data retention are more important. If he had the budget, I'd be suggesting looking at something like Copan's MAID system. _______________________________________________ CentOS mailing list CentOS(a)centos.org http://lists.centos.org/mailman/listinfo/centos -- Jason Luck favors the prepared. ______________________________________________________________________ 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] I need storage server advice
by Ross S. W. Walker 07 May '08

07 May '08

Take these benchmarks with a grain of salt. We don't know how these hardware controllers were setup and by the numbers posted, not very well, or they are not very good. A SATA and a SAS drive will have roughly the same sequential io performance. Where SAS shines is in random io. So if it's archive, buy SATA. 65MB/s is roughly what you will see with a single SAS or SATA drive on reads, around 30MB/s for writes. Sequential io is measured in MB/s and random io in IOPS or ios per second. Each spindle in a stripe set will roughly add 50% perf to sequential io and add to the IOPS by the IOPS of the spindle (IOPS+IOPS...). A mirror counts as 1 spindle for reads and 1/2 a spindle for writes (unless RAID is capable of doing parallel reads then it counts as 1 1/2 of reads). A RAID 5 is always one less spindle due to parity and each spindle on writes counts as 1/#spindles (write-back cache helps lessen that hurt). For 4k sequential ios (larger block sizes will post larger numbers). 1 spindle = 65MB/s and 175 IOPS 2 spindles = 97.5MB/s and 350 IOPS 3 spindles = 146.25MB/s and 525 IOPS 4 spindles = 219.375MB/s and 700 IOPS (175 IOPS is from 15K SAS with 3.5ms read seek and 2ms avg latency, figure 80 IOPS for good SATA drive) Now any performance below those numbers is a failure of the RAID system and any performance above those numbers is due to caching and read-ahead. I hope that helps. -Ross ----- Original Message ----- From: centos-bounces(a)centos.org <centos-bounces(a)centos.org> To: CentOS mailing list <centos(a)centos.org> Sent: Tue May 06 17:20:16 2008 Subject: Re: [CentOS] I need storage server advice I just posted this on my website, oddly enough. While you need to really understand your storage requirements to make an informed choice between hardware or software RAID, with quad core CPUs being as cheap as they are it's hard to not make the argument for software. This is just hdparm over an average of 5 runs each on very similar machines. 5 disc SAS array with 136g 10k drives and a hardware controller Timing cached reads: 13336 MB in 2.00 seconds = 6673.96 MB/sec Timing buffered disk reads: 98 MB in 1.18 seconds = 83.31 MB/sec 4 disc RAID 5 with 3Ware 9650SE and 500g 7200RPM drives Timing cached reads: 6576 MB in 2.00 seconds = 3293.08 MB/sec Timing buffered disk reads: 448 MB in 3.00 seconds = 149.20 MB/sec Single 500g 7200 RPM SATA drive Timing cached reads: 14220 MB in 2.00 seconds = 7119.78 MB/sec Timing buffered disk reads: 198 MB in 3.02 seconds = 65.51 MB/sec 6 500g 7200 RPM SATA drives in a software RAID 5 array Timing cached reads: 14364 MB in 2.00 seconds = 7191.86 MB/sec Timing buffered disk reads: 852 MB in 3.00 seconds = 283.64 MB/sec Jason www.cyborgworkshop.org Michael Semcheski wrote: > On Tue, May 6, 2008 at 3:11 PM, Ed Morrison <edward.morrison(a)gmail.com > <mailto:edward.morrison@gmail.com>> wrote: > > Situation: > My current storage needs are approximately 1.5 TB annually. This > will increase to about 3.5 TB annually over the next 5 years (rough > est.). This box will just be a data archive and once it is full it > will only be used very infrequently if not used at all. Files are > small up to 10 MB but numerous. > > > The solution I found best was to buy a 2U server that has 8*750GB disks, > though they'd probably be 1TB today. Put the disks into a RAID 5 or 6. > Using hardware RAID, divvy them up into one 50GB drive, and one really > large drive. Put the OS on the 50GB drive, mount the really big drive. > > Now you have a 50GB drive and a 7*750-50 drive. When you fill that up, > just buy another 2U server. When you do fill it up, the next one will > be cheaper and or bigger. > > The keys to this type of setup are: > 1) Don't buy storage you'll need next year today. The best time to buy > this kind of hardware is right before you need it. > 2) Look at the overall cost per gigabyte. That's the metric that drives > things. > 3) Understand your tolerance for downtime and data protection. If you > have another copy, or a backup, and its not mission critical data, its > much cheaper not to waste disks on redundancy. > > We have tape backups of our systems, and factoring in the cost of tape > and other costs, its still possible to get storage with a marginal cost > below $1 / GB. That includes a 3 year warranty, quad core processor, > 4GB of RAM which you can probably put to use elsewhere. > > > > ------------------------------------------------------------------------ > > _______________________________________________ > CentOS mailing list > CentOS(a)centos.org > http://lists.centos.org/mailman/listinfo/centos _______________________________________________ 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.

3 2

Postfix+MySQL - how to create DB
by Kanwar Ranbir Sandhu 07 May '08

07 May '08

Hi All, I'm toying around with Postfix and MySQL on a CentOS 4 server (no longer using stock postfix and mysql rpms, obviously). I've read several "How-TOs", and it all looks fairly easy to do. The one thing that puzzles me is the table structure for the postfix mysql database: where is everyone getting it? Also, I've noticed that some people create more tables than others. But, this looks like it's just based on which bits of postfix people want to put into the database. I can just copy the SQL people have posted to create the tables I want. I'd much rather know if there is an official source for this, though. So far I haven't found it. Regards, Ranbir -- Kanwar Ranbir Sandhu Linux 2.6.22.14-72.fc6 i686 GNU/Linux 22:25:36 up 9 days, 16:23, 2 users, load average: 0.29, 0.27, 0.27

3 2

I need storage server advice
by Ed Morrison 06 May '08

06 May '08

Hi: I need advice on implementing a storage server. I really do not have the $ to spend for a Dell iSCSI storage divice and I am thinking trunning CentOS 5.x with ftp or FreeNAS. Here is what I am looking at and concerned about. Situation: My current storage needs are approximately 1.5 TB annually. This will increase to about 3.5 TB annually over the next 5 years (rough est.). This box will just be a data archive and once it is full it will only be used very infrequently if not used at all. Files are small up to 10 MB but numerous. CentOS: Upgrading to the newer CentOS flavors. I will not have the ability to archive this data to tape and I am concerned about loosing the data when upgrading the OS. How best to handle this? Storage limitation. It is my understanding that there is a 2 TB storage limitation with Linux (and windows) in general particularly for stability. I see that ReiserFS can go up to 16 TB. Is any one using this? If so, how has it been for you? FreeNAS Anyone using FreeNAS? What is your experience? How easy is it to add new drives and keep your data? Upgrading to newer versions? Thanks, Ed

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ext3 filesystems larger than 8TB
by Monty Shinn 06 May '08

06 May '08

Greetings. I am trying to create a 10TB (approx) ext3 filesystem. I am able to successfully create the partition using parted, but when I try to use mkfs.ext3, I get an error stating there is an 8TB limit for ext3 filesystems. I looked at the specs for 5 on the "upstream" vendor's website, and they indicate that there is a 16TB limit on ext3. Has anyone been able to create a ext3 filesystem larger than 8TB? If ext3 isn't an option, has anyone used the kmod-xfs-smp.i686 module mentioned on the centos site? Surely it doesn't have an 8TB limit... specs: Centos 5.1 kernel-2.6.18-53.1.14.el5 3Ware 9550SXU 12port raid card Am I just walking into a big nightmare? Any thoughts would be greatly appreciated. Thanks, Monty

10 24

httpd reverse proxy
by Craig White 06 May '08

06 May '08

I am trying to figure this out and I always seem to have trouble configuring apache to do more than basic stuff... I have a web server that has several cnames assigned to it. I want srv1.tobyhouse.com to be served by apache. I want to proxy connections to www.tobyhouse.com to cms.tobyhouse.com (different system) If I do this... <VirtualHost www.tobyhouse.com:*> ProxyPass / http://cms.tobyhouse.com ProxyPassReverse / http://cms.tobyhouse.com </VirtualHost> then I am good but it seemed to not pull the assets like css and javascripts from cms.tobyhouse.com When I did this... <VirtualHost www.tobyhouse.com:*> RedirectPermanent / http://cms.tobyhouse.com </VirtualHost> It sent ALL traffic over to the other server which is clearly not what I want. How can handle this? Must I give a unique ip address to www.tobyhouse.com? Craig

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Discuss May 2008