Discuss April 2011

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312 participants
282 discussions

40TB File System Recommendations
by Matthew Feinberg 18 Apr '11

18 Apr '11

Hello All I have a brand spanking new 40TB Hardware Raid6 array to play around with. I am looking for recommendations for which filesystem to use. I am trying not to break this up into multiple file systems as we are going to use it for backups. Other factors is performance and reliability. CentOS 5.6 array is /dev/sdb So here is what I have tried so far reiserfs is limited to 16TB ext4 does not seem to be fully baked in 5.6 yet. parted 1.8 does not support creating ext4 (strange) Anyone work with large filesystems like this that have any suggestions/recommendations? -- Matthew Feinberg matthew(a)choopa.com AIM: matthewchoopa

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Gnome Notification Applet
by Ron Blizzard 18 Apr '11

18 Apr '11

I tried out Scientific Linux 6 Live to see (basically) what I can expect with CentOS 6 and was pleased to find that everything looks pretty familiar and is easily customizable to make it look and feel like 5.6 -- except for one thing that I also noticed in Ubuntu's newest beta (my Dad uses Linux Mint). For whatever reason, Gnome has decided to put the Volume Control and Network Manager in the Notification Applet. (It's worse with Ubuntu, they've put four applets there by default.) On my desktop I don't display the Network Manager, but I like the Volume Control to be there (on the very right beside the clock). I spent most of my "trial time" with SL 6 trying to figure out how to separate these two applets from the Notification Applet -- without success. Is there a configuration file I can change or a configuration program I can run to customize this? I realize it's not a huge deal, but it's an irritant. Why does Gnome want to limit the ability to customize? Thanks for any pointers. -- RonB -- Using CentOS 5.6

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Script Problem
by Matt 17 Apr '11

17 Apr '11

I have a script I put in /etc/cron.fiveminutes graphs.sh #!/bin/sh env LANG=C mrtg /home/admin/domains/my---server.com/public_html/traffic/load/mrtg.cfg --logging /dev/null >/dev/null 2>&1 env LANG=C mrtg /home/admin/domains/my---server.com/public_html/traffic/eth0/mrtg.cfg --logging /dev/null >/dev/null 2>&1 #exit 0; Problem is there is some bug that raises an error even though mrtg still graphs fine. [root@server cron.fiveminutes]# env LANG=C mrtg /home/admin/domains/my---server.com/public_html/traffic/eth0/mrtg.cfg --logging /dev/null Subroutine SNMPv1_Session::AF_INET6 redefined at /usr/lib/perl5/5.8.8/Exporter.pm line 65. at /usr/bin/../lib64/mrtg2/SNMP_Session.pm line 594 Subroutine main::AF_INET6 redefined at /usr/lib/perl5/5.8.8/Exporter.pm line 65. at /usr/bin/mrtg line 97 /usr/bin/rateup: /usr/local/lib/libpng12.so.0: no version information available (required by /usr/lib64/libgd.so.2) The issue is it tries to alert root every time this script is run. I thought adding the ">/dev/null 2>&1" would stop that but it does not. Is there anyway to get the script to ignore the error and not alert root? Another solution is to install a newer version of mrtg from source which supposedly resolves the issue but I would rather just ignore the error for now until a newer 64bit rpm comes out since its not hurting anything except the annoying warning messages.

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2 encrypted VG's on 1 disk - HOW?
by johhny_at_poland77 17 Apr '11

17 Apr '11

I don't think it's a "distro related" issue, so i'm posting it here too: http://unix.stackexchange.com/questions/11289/how-to-install-fedoraubuntu-w… what am i missing? why doesn't GRUB offer the 2 distros@boot, why is it only offering only 1?? why doesn't it sees the other one?? Thanks for any help...

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ksplice within CentOS
by Marian Marinov 17 Apr '11

17 Apr '11

Hello guys, I saw that a few days back there was a talk about encorporating the ksplice toolchain into CentOS and creating rebootless upgrades to the CentOS kernel. I'm really interested in helping for that. Where/how we can start work ? Best regards, Marian Marinov

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timezone issue
by Tim Dunphy 17 Apr '11

17 Apr '11

hey list! having a slightly odd time issue on one host... can I get some help with this? This is the current time from a working system: Sun Apr 17 00:28:18 EDT 2011 However from the problem system this is the time: Sat Apr 16 20:30:01 EDT 2011 I have set the time zone as such: lrwxrwxrwx 1 root root 23 Apr 16 19:41 /etc/localtime -> /usr/share/zoneinfo/EST But when I run ntpdate it returns the wrong time: 16 Apr 19:46:13 ntpdate[1968]: step time server 204.235.61.9 offset 14408.651330 sec [root@VIRTCENT08:/etc] #date Sat Apr 16 19:46:42 EST 2011 can someone hit me upside the head with the cluehammer? tx!

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To PAE or not to PAE...
by John Doe 16 Apr '11

16 Apr '11

Hi, I was wondering if anyone would know the cons of running a PAE kernel...? I have a 4GB pc and was wondering if it was worth going the PAE way to gain those exta 700MB... In the past, I heard that these 700MB were normally reserved for bios or chipset stuff... And that running in PAE would slow down some processes. By the way, I know 64 bits would solve this dilemn but right now I am 32bits... Thx, JD

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Re: [CentOS] 40TB File System Recommendations
by Christopher Chan 16 Apr '11

16 Apr '11

> > As matter of interest, does anyone know how to use an SSD drive for cach > purposes on Linux software RAID drives? ZFS has this feature and it > makes a helluva difference to a storage server's performance. You cannot. You can however use one for the external journal of ext3/4 in full journaling mode for something similar.

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Re: [CentOS] 40TB File System Recommendations
by Ross Walker 15 Apr '11

15 Apr '11

On Apr 15, 2011, at 12:32 PM, Rudi Ahlers <Rudi(a)SoftDux.com> wrote: > > > On Fri, Apr 15, 2011 at 6:26 PM, Ross Walker <rswwalker(a)gmail.com> wrote: > On Apr 15, 2011, at 9:17 AM, Rudi Ahlers <Rudi(a)SoftDux.com> wrote: > >> >> >> On Fri, Apr 15, 2011 at 3:05 PM, Christopher Chan <christopher.chan(a)bradbury.edu.hk> wrote: >> On Friday, April 15, 2011 07:24 PM, Benjamin Franz wrote: >> > On 04/14/2011 09:00 PM, Christopher Chan wrote: >> >> >> >> Wanna try that again with 64MB of cache only and tell us whether there >> >> is a difference in performance? >> >> >> >> There is a reason why 3ware 85xx cards were complete rubbish when used >> >> for raid5 and which led to the 95xx/96xx series. >> >> _ >> > >> > I don't happen to have any systems I can test with the 1.5TB drives >> > without controller cache right now, but I have a system with some old >> > 500GB drives (which are about half as fast as the 1.5TB drives in >> > individual sustained I/O throughput) attached directly to onboard SATA >> > ports in a 8 x RAID6 with *no* controller cache at all. The machine has >> > 16GB of RAM and bonnie++ therefore used 32GB of data for the test. >> > >> > Version 1.96 ------Sequential Output------ --Sequential Input- >> > --Random- >> > Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- >> > --Seeks-- >> > Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP >> > /sec %CP >> > pbox3 32160M 389 98 76709 22 91071 26 2209 95 264892 26 >> > 590.5 11 >> > Latency 24190us 1244ms 1580ms 60411us 69901us >> > 42586us >> > Version 1.96 ------Sequential Create------ --------Random >> > Create-------- >> > pbox3 -Create-- --Read--- -Delete-- -Create-- --Read--- >> > -Delete-- >> > files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP >> > /sec %CP >> > 16 10910 31 +++++ +++ +++++ +++ 29293 80 +++++ +++ >> > +++++ +++ >> > Latency 775us 610us 979us 740us 370us >> > 380us >> > >> > Given that the underlaying drives are effectively something like half as >> > fast as the drives in the other test, the results are quite comparable. >> >> Woohoo, next we will be seeing md raid6 also giving comparable results >> if that is the case. I am not the only person on this list that thinks >> cache is king for raid5/6 on hardware raid boards and the using hardware >> raid + bbu cache for better performance one of the two reasons why we >> don't do md raid5/6. >> >> >> > >> > Cache doesn't make a lot of difference when you quickly write a lot more >> > data than the cache can hold. The limiting factor becomes the slowest >> > component - usually the drives themselves. Cache isn't magic performance >> > pixie dust. It helps in certain use cases and is nearly irrelevant in >> > others. >> > >> >> Yeah, you are right - but cache is primarily to buffer the writes for >> performance. Why else go through the expense of getting bbu cache? So >> what happens when you tweak bonnie a bit? >> _______________________________________________ >> >> >> >> As matter of interest, does anyone know how to use an SSD drive for cach purposes on Linux software RAID drives? ZFS has this feature and it makes a helluva difference to a storage server's performance. > > Put the file system's log device on it. > > -Ross > > > _______________________________________________ > > > > Well, ZFS has a separate ZIL for that purpose, and the ZIL adds extra protection / redundancy to the whole pool. > > But the Cache / L2ARC drive caches all common reads & writes (simply put) onto SSD to improve overall system performance. > > So I was wondering if one could do this with mdraid or even just EXT3 / EXT4? Ext3/4 and XFS allow specifying an external log device which if is an SSD can speed up writes. All these file systems aggressively use page cache for read/write cache. The only thing you don't get is L2ARC type cache, but I heard of a dm-cache project that might provide provide that type of cache. -Ross

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Two cleanly installed CentOS 5.6 servers but with different Xen kernel versions
by Hans Vos 15 Apr '11

15 Apr '11

Hello, Earlier this week I installed a test server with CentOS 5.6 with Virtualization enabled during the installer. Today I installed another server using the same method (they are identical servers). I just did a yum update and I found something curious. Both servers have a different kernel. Server 1 is at 9.1 version and server 2 at 5.1. How can this be? How to I get the latest version on server 2? If I run yum update there are none available. If I input xm info I get this one server 1: host : server1 release : 2.6.18-238.9.1.el5xen version : #1 SMP Tue Apr 12 18:53:56 EDT 2011 machine : x86_64 nr_cpus : 4 nr_nodes : 1 sockets_per_node : 1 cores_per_socket : 4 threads_per_core : 1 cpu_mhz : 2400 hw_caps : bfebfbff:20100800:00000000:00000940:0000e3bd:00000000:00000001 total_memory : 4095 free_memory : 383 node_to_cpu : node0:0-3 xen_major : 3 xen_minor : 1 xen_extra : .2-238.9.1.el5 xen_caps : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 hvm-3.0-x86_32p hvm-3.0-x86_64 xen_pagesize : 4096 platform_params : virt_start=0xffff800000000000 xen_changeset : unavailable cc_compiler : gcc version 4.1.2 20080704 (Red Hat 4.1.2-50) cc_compile_by : mockbuild cc_compile_domain : centos.org cc_compile_date : Tue Apr 12 18:01:03 EDT 2011 xend_config_format : 2 And on server 2 it is this: host : server2 release : 2.6.18-238.5.1.el5xen version : #1 SMP Fri Apr 1 19:35:13 EDT 2011 machine : x86_64 nr_cpus : 4 nr_nodes : 1 sockets_per_node : 1 cores_per_socket : 4 threads_per_core : 1 cpu_mhz : 2400 hw_caps : bfebfbff:20100800:00000000:00000940:0000e3bd:00000000:00000001 total_memory : 4095 free_memory : 383 node_to_cpu : node0:0-3 xen_major : 3 xen_minor : 1 xen_extra : .2-238.5.1.el5 xen_caps : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 hvm-3.0-x86_32p hvm-3.0-x86_64 xen_pagesize : 4096 platform_params : virt_start=0xffff800000000000 xen_changeset : unavailable cc_compiler : gcc version 4.1.2 20080704 (Red Hat 4.1.2-50) cc_compile_by : mockbuild cc_compile_domain : centos.org cc_compile_date : Fri Apr 1 18:30:53 EDT 2011 xend_config_format : 2 -- Met vriendelijke groet / With kind regards, Hans Vos

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Discuss April 2011