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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!

3 3

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

1 0

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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[OT] ups advice
by admin lewis 15 Apr '11

15 Apr '11

Hi I have a Dell PowerEdge T310 *tower* server.. I have to buy an ups by apc... anyone could help me giving an hint ? a simple "smart ups 1000" could be enough ? thx so much!! lewis.

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php53 and MSSQL
by John Beranek 15 Apr '11

15 Apr '11

[Reposted now I've joined the list, so I hopefully don't get moderated out] Hi, I've upgraded lots of machines to 5.6 (thanks!) and there was one particular machine that I'd also like to upgrade to PHP 5.3. Unfortunately it seems I can't. On the machine I have php-mssql installed, and it appears that there is no php53-mssql. php-mssql is built from the php-extras SRPM, so is there going to be a php53-extras SRPM? I've checked upstream, and they also don't have a php53-mssql package, so if there _were_ to be solved it'd have to be in the 'Extras' repository I guess... Cheers, John. -- John Beranek To generalise is to be an idiot. http://redux.org.uk/ -- William Blake

2 3

php53 and mcrypt
by Geoff Galitz 15 Apr '11

15 Apr '11

More PHP fun! I can see in the spec files that php-mcrypt support was removed by Redhat. I tried to find out why but I don't have sufficient access to redhat bugzilla. I am wondering if it is actually necessary as I have also run across a post or two that indicates applications that rely on mcrypt still work with the new php53. Perhaps mcrypt was superceded by another module or PHP core code?

3 2

php53 and eacclerator
by Geoff Galitz 15 Apr '11

15 Apr '11

Hi. There does not seem to be a php53-eaccelerator in standard Centos yum channels, from what I can see. That is a mainstay for us. Has anyone found that any particular php53-eacclerator from other locations play well with it? Thanks.

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