[Lustre-discuss] lustre performance question (contd)

[Balagopal Pillai]

Hi,

     Please ignore the previous email. It seemed to solve itself after 10 
- 15 minutes of mounting the filled volume. Now it is as fast as the empty 
volumes.

Thanks
Balagopal

---------- Forwarded message ----------
Date: Tue, 25 Dec 2007 10:36:28 -0400 (AST)
From: Balagopal Pillai <pillai at mathstat.dal.ca>
To:  <lustre-discuss at clusterfs.com>
Subject: lustre performance question

Hi,

         We have one Lustre volume that is getting full and some other 
volumes that are totally empty. The one that is full is a little sluggish 
at times with the following messages appearing in syslog on the OSS -

Lustre: 5809:0:(filter_io_26.c:698:filter_commitrw_write()) data1-OST0001: 
slow i_mutex 82s
Lustre: 5809:0:(filter_io_26.c:711:filter_commitrw_write()) data1-OST0001: 
slow brw_start 82s
Lustre: 5809:0:(filter_io_26.c:763:filter_commitrw_write()) data1-OST0001: 
slow direct_io 82s
Lustre: 5809:0:(filter_io_26.c:776:filter_commitrw_write()) data1-OST0001: 
slow commitrw commit 82s

           But the same two OSS are also exporting the empty volume, which 
is very fast on any tests (like creation of a tar file, bonnie etc etc)
I also tested the same thing on the nfs exported backup volume of the 
filled up lustre volume (exported from the same OSS server) and it doesn't 
show any significant slow down. Is it normal for Lustre volumes to slow 
down when the volumes get full? 

Thanks
Balagopal