9 Feb
2011
9 Feb
'11
9:34 a.m.
The stats in the SAN after the change maildir->mdbox do not help, we have zlib enabled in lda& imap with mdbox, so our # of real IOPs is lower than Maildir (we did not have zlib enabled)
I wonder how large a write can be before it is split to two iops.. With NFS probably smaller I'd guess. Still, I would have thought that even if zlib writes only half as much, the disk iops difference wouldn't be nearly as much.
Without zlib our mailstore was 2.1 TB. With zlib enabled is 1.4 TB. We use a iSCSI SAN with ext4. I am writing a document with some benchmarking of dovecot (postal & rabid software) with some graphs about # of iops, cpu load, and so... I am still writing it if you are interested I can post a link to the document in the list.
Regards
Javier