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On Jul 14, 2004 12:54 -0600, Sonja Tideman wrote:> I am seeing low read rates, where reads are typically range from
> 200-300MB/s (versus writes, which are getting in the 500-600 MB/s range).
> This is on a system with the 2MB stripe size, striping over 8 OSTs. I am
> running 1.2.1.10. This is running a test where writes and reads requests
> are 4MB in size. Has anyone else seen this? Would upgrading to a newer
> version (1.2.2 or 1.2.3) help?
You will probably notice an improvement when 1.2.4 is available. Until then
you can do some tuning. Interestingly, turning off the read cache on the OSTs
will improve performance for both read and write of large files because the
OST can keep more filesystem metadata in RAM and not have to wait for many
small metadata reads in order to complete the larger data reads. For
"cold"
files this doesn''t help much, but it is noticable for files recently
written.
On the clients:
# turn off debugging (default =3D 0x3f0400 if you are submitting a bug report!)
echo 0 > /proc/sys/portals/debug
for OSC in /proc/fs/lustre/osc/OSC*/; do
# increase number of concurrent requests to each OST
echo 8 > $OSC/max_rpcs_in_flight
# increase client-side writeback cache
echo 64 > $OSC/max_dirty_mb
done
=20
On the OSTs:
# turn off debugging (default =3D 0x3f0400 if you are submitting a bug report!)
echo 0 > /proc/sys/portals/debug
for OST in /proc/fs/lustre/obdfilter/OST*/; do
# only read cache files up to 32MB, not larger files
echo $((32 * 1024 * 1024)) > $OST/readcache_max_filesize
done
Cheers, Andreas
--
Andreas Dilger
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