On 2007-03-24, Peer Heinlein <[EMAIL PROTECTED]> wrote: > > At the moment we have about 30.000 Accounts with round about 150 GByte > mailspace, located on a NFS-storage with 7.200 RPM RAID-1-SATA-discs. We > have two Postfix- and two IMAP-Nodes.
We have 100-150.000 active accounts, using ~600GB for Maildirs. Our cluster is 5 nodes (2x incoming smtp, 1x mysql user database, 1x webmail and 1x courier pop/imap), all accessing the users Maildirs on a clusterfs (IBM GPFS) which is SAN-attached to all nodes. I think this is a very good setup, and we can easily extend it by adding more nodes -- or balance the load by running pop/imap and webmail on the same nodes. (Additionaly there are spam and virus scanners in front of the incoming smtp-servers) > The performance on the discs are bad -- iostat shows up to 100% IO-usage. The dedicated pop/imap host shows ~6-7% iowait, webmail ~20% iowait, smtps 5-20% iowait.. > > For sure -- it's possibe to build a better NFS-storage with 15.000 RPM > SCSI -- but we have to scale up to 60.000 or 90.000 Accounts with 400 / > 500 GByte Maildir-Data. But will that help? I can't believe that tuning > the discs gives enough performance boost. Otherwise: I can not believe > that it is necessary to buy a very expensive NetApp-Storage for just some > hundred gigs of Maildir-storage. IMHO a cheap FC attached disk system, with a good clusterfs like GPFS should give enough performance. We use an IBM DS4800 which 3 drawers of 15K FC disks, but I'd guess a cheaper solution would work perfectly well too. With GPFS you'll easily scale out the load as you add more disk- systems/controllers. > Looks like a frequently used Maildir-storage > 250 Gbyte is to hard for > less then 10 harddiscs, because it's to much I/O. Cache would give a > performance boost -- should I give my NFS-server > 10 GByte RAM just for > caching? I would stay away from NFS if I could.. I don't think it's suitable for maildir, and it's often a single-point-of-failure, as HA-NFS seems hard. -jf ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Courier-imap mailing list [email protected] Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-imap
