[Lustre-discuss] raid5 patches for rhel5

[Robin Humble]

On Sun, Jul 20, 2008 at 11:08:41PM -0600, Andreas Dilger wrote:
>On Jul 18, 2008  08:39 -0400, Robin Humble wrote:
>> I notice that Lustre 1.6.5 brings with it the md layer RAID5 patches
>> for RHEL5 kernels. thanks! :-)
>> are all the RHEL4 optimisations there, so we should get the same
>> performance if we now move our OSS's to RHEL5?
>That is my understanding, yes.

done, and yes, performance is largely the same as RHEL4. cool!

Version  1.03       ------Sequential Output------ --Sequential Input- --Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine   Size:chnk K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
rhel4 oss  16G:256k 84624  99 842138 92 310044 91 77675  99 491239 96 285.8  10
rhel5 oss  16G:256k 86085  99 827731 95 327007 97 79639 100 495487 98 456.2  18

streaming writes are down marginally on rhel5, but seeks/s are up 50%.

BTW - the above is with 1.6.4.3 clients.
1.6.5.1 client still perform badly for us. eg.

Version  1.03       ------Sequential Output------ --Sequential Input- --Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine   Size:chnk K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
           16G:256k 77216  99 462659 100 296050  96 68100  81 648350  93 422.2  13

which shows better streaming writes, but ~1/2 the streaming read speed :-(

> Note that there are also similar
>performance improvements for RAID-6.

I can't see the RAID6 patches in the tree for RHEL5... am I missing
something?

cheers,
robin