Bill Moore wrote:
On Fri, Dec 08, 2006 at 12:15:27AM -0800, Ben Rockwood wrote:
Clearly ZFS file creation is just amazingly heavy even with ZIL
disabled. If creating 4,000 files in a minute squashes 4 2.6Ghz Opteron
cores we're in big trouble in the longer term. In the meantime I'm
going to find a new home for our IMAP Mail so that the other things
served from that NFS server at least aren't effected.
For local tests, this is not true of ZFS. It seems that file creation
only swamps us when coming over NFS. We can do thousands of files a
second on a Thumper with room to spare if NFS isn't involved.
Next step is to figure out why NFS kills us.
Agreed. If mass file creation was a problem locally I'd think that we'd
have people beating down the doors with complaints.
One thought I had as a work around was to move all my mail on NFS to an
iSCSI LUN and then put a Zpool on that. I'm willing to bet that'd work
fine. Hopefully I can try it.
To round out the discussion, the root cause of this whole mess was
Courier IMAP Locking. After isolating the problem last night and
writing a little d script to find out what files were being create it
was obviously lock files, turn off locking and file creations dropped to
a reasonable level and our problem vanished.
If I can help at all with testing or analysis please let me know.
benr.
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