We have clients which issue LIST "" * when they start up. We think we need them to do this, because we are making quite heavy use of shared mailboxes so a mailbox may arrive in a hierarchy other than INBOX.* to which the user should subscribe. We have ~35K mailboxes (as reported by ctl_mboxlist -d | wc -l), and the LIST takes upwards of 5 minutes. The imapd spins as much CPU as it can get hold of, too. We assumed this was down to our elderly hardware (a 4x650MHz E450, albeit front-ending fast NAS store) but a freshly installed 8-core T2000 with 16GB of RAM and only one imapd executing takes a similar amount of time. The production mailserver is now perfectly usable with a load average of >100 thanks to the wonders of Solaris 10 FSS, but the five minute responses to LIST "" * cause clients some distress. We had hoped the move to the T2000 would solve the problem, but today's testing shows the new machine doesn't make a significant difference. The old machine is running 2.2.8, the new machine is running 2.3.9. The old machine has configdir (/var/imap) striped over four spindles and then mirrored into four spindles, the new machine has /var/imap in ZFS filesystem of four disks, again mirrored in pairs. The imap daemon that is spinning servicing the LIST "" * doesn't appear to do any I/O (other than regularly stating mailboxes.db), so I don't think disk performance is at issue anyway. foolstupidclients: 1 would obviously help the performance, but would break the shared mailboxes. I could modify tghe code to provide a limited form of foolstupidclients, which would turn on the option for users who don't need shared mailboxes but leave it off for those that do. But at root I don't understand why LIST "" * should take any longer than, for example, ctl_mboxlist -d. Before I wade into the code, can anyone make any helpful suggestions? ian ---- Cyrus Home Page: http://cyrusimap.web.cmu.edu/ Cyrus Wiki/FAQ: http://cyrusimap.web.cmu.edu/twiki List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html
