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<DIV dir=ltr align=left><SPAN class=700210302-14042009><FONT
size=2>Danny,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=700210302-14042009><FONT
size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=700210302-14042009><FONT size=2>Have you
tried any "gfs_tool settune" options with your setup? Aside from defaults,
on GFS1 we use:</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=700210302-14042009><FONT
size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=700210302-14042009><FONT
size=2>
gfs_tool settune $fs demote_secs
7200<BR>
gfs_tool settune $fs glock_purge
50<BR>
gfs_tool settune $fs statfs_fast 1<BR></FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=700210302-14042009><FONT size=2>You might
want to experiment a bit, especially with the first two. It's hard to
guess at the cause of the slowdown you are experiencing without more
information, but gfs_scand thrashing is one possibility.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=700210302-14042009><FONT
size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=700210302-14042009><FONT size=2>There have
been many prior articles posted on GFS performance. Search for e.g. "glock
trimming patch".</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=700210302-14042009><FONT
size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=700210302-14042009><FONT size=2>If possible,
mount your GFS filesystems with noatime as well.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=700210302-14042009><FONT
size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=700210302-14042009><FONT
size=2>Jeff</FONT></SPAN></DIV><FONT size=2></FONT><FONT size=2></FONT><FONT
size=2></FONT><FONT size=2></FONT><BR>
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<HR tabIndex=-1>
<FONT size=2><B>From:</B> linux-cluster-bounces@redhat.com
[mailto:linux-cluster-bounces@redhat.com] <B>On Behalf Of </B>Danny
Wall<BR><B>Sent:</B> Monday, April 13, 2009 9:46 PM<BR><B>To:</B>
linux-cluster@redhat.com<BR><B>Subject:</B> [Linux-cluster] GFS file
size/performance question<BR></FONT><BR></DIV>
<DIV></DIV>I realize that GFS is not the most optimized filesystem for a lot
of small files, but at what point does that become a concern? Is it when you
have a lot of files less than 1MB? Less than 10MB?<BR><BR>We have five Red Hat
clusters. The original system is RHEL 4.4 with RHCS and GFS. Most filesystems
are 2TB LUNs on a Fibre Channel SAN, with hundreds of thousands of folders
(50,000 at root) and millions of files. The files range from 60KB to
about 5MB each, with 20-100 files in each folder. <BR><BR>We are having a
problem with the new cluster. After a while of being on a node, the
performance is horrible until we migrate the users to a different node. There
are no issues with RAM, CPU, disk or NIC IO. <BR><BR>The new cluster servers
are RHEL 5.1 with RHCS and GFS. There are currently 4 folders off root, with
5,000-7,000 sub-folders each. The folders generally hold approx. 10-100 files,
ranging in size from 1k to 5MB. Several of these folders have 100 files all
less than 1MB. The three servers in one cluster have a single 2TB FC LUN
attached using GFS. Service to the files is generally only provided from one
node at a time, except off hours during backups, so there should not be a lot
of locking issues.<BR><BR>Both clusters are running samba that comes with the
respective versions of RHEL, for WinXP and Win2003 workstations in a Win2003
AD domain.<BR><BR>Is it possible that GFS performance is worse on the newer,
more powerful cluster nodes because there are so many files under 100k? At
what point does GFS performance really start taking a hit due to smaller file
sizes?<BR><BR>The newer servers all have 32GB RAM and 8 CPU cores.<BR><PRE>
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