[Lustre-discuss] tuning max_sectors

[Stuart Midgley]

Even if max_hw_sectors_in=32767?

--
Stuart Midgley Ph.D.
Manager Production Services
DownUnder GeoSolutions
stuartm at dugeo.com

On 18/04/2009, at 3:06, Andreas Dilger <adilger at sun.com> wrote:

> On Apr 17, 2009  08:40 -0400, Robin Humble wrote:
>> we have a similar problem.
>>  Lustre: short-OST0001: underlying device md0 should be tuned for  
>> larger I/O requests: max_sectors = 1024 could be up to  
>> max_hw_sectors=1280
>>
>> sadly, that sys entry doesn't exist:
>>  cat: /sys/block/md0/queue/max_sectors_kb: No such file or directory
>>
>> do you have any other suggestions?
>> perhaps the devices below md need looking at?
>> they all report /sys/block/sd*/queue/max_sectors_kb == 512.
>> we have an md raid6 8+2.
>
> Since MD RAID is really composed of underlying disks, and doing the
> mapping from /dev/md0 -> /sys/block/sd* is difficult, mount.lustre
> can't do the tuning itself.  Instead, you should add a line into
> /etc/init.d/rc.local like:
>
> for DEV in sdc sdl sdk sdj sdi sdh sdg sdf sde sdd; do
>    cp /sys/block/$DEV/queue/{max_hw_sectors_kb,max_sectors_kb}
> done
>
>> uname -a
>>  Linux sox2 2.6.18-92.1.10.el5_lustre.1.6.6.fixR5 #2 SMP Wed Feb 4  
>> 16:58:30 EST 2009 x86_64 x86_64 x86_64 GNU/Linux
>> (which is 1.6.6 + the patch from bz 15428 which is (I think) now in  
>> 1.6.7.1)
>>
>> cat /proc/mdstat
>> ...
>> md0 : active raid6 sdc[0] sdl[9] sdk[8] sdj[7] sdi[6] sdh[5] sdg[4]  
>> sdf[3] sde[2] sdd[1]
>>      5860595712 blocks level 6, 64k chunk, algorithm 2 [10/10]  
>> [UUUUUUUUUU]
>>                in: 64205147 reads, 97489370 writes; out: 3730773413  
>> reads, 3281459807 writes
>>                2222983790 in raid5d, 498868 out of stripes, 4280451425 
>>  handle called
>>                reads: 0 for rmw, 709671189 for rcw. zcopy writes: 1573400576 
>> , copied writes: 20983045
>>                0 delayed, 0 bit delayed, 0 active, queues: 0 in, 0  
>> out
>>                0 expanding overlap
>>
>> cheers,
>> robin
>> _______________________________________________
>> Lustre-discuss mailing list
>> Lustre-discuss at lists.lustre.org
>> http://lists.lustre.org/mailman/listinfo/lustre-discuss
>
> Cheers, Andreas
> --
> Andreas Dilger
> Sr. Staff Engineer, Lustre Group
> Sun Microsystems of Canada, Inc.
>
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