Hmm, it seems strange (and rather unsafe) that you would run a mail
spool without using sync I/O. Unfortunate too, because sync I/O with
a large journal (and perhaps an external journal disk) would give you
very fast throughput on ext3.
> We're using dotlocking. Would this cause metadata journalling?
> I estimate about 200 - 300 dotlock files are created per second, but
> these should all be asynchronous.
Lots of it. So, that is 250 * (1 dir block + 1 inode bitmap + 1 inode
table block (+ 1 block bitmap + 1 data block, if there is data in the
dotlock file)) = 1250 blocks/second or so.
> Would switching to fctnl() locking (if this works over NFS) solve the
Probably (no disk I/O generated), but I don't know the state of NFS locking.
> We had to hash the mail spool a long time ago do to system time eating all
> CPU (the ext2 linear directory scan to find a slot available in the spool
> directory to add the dotlock file).
One reason why we are adding hash-indexed directory support to ext3, so
that you don't have to implement it in each application.
-- Andreas Dilger http://www-mddsp.enel.ucalgary.ca/People/adilger/ http://sourceforge.net/projects/ext2resize/
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