Hi!
[First: I read the discussion "Courier-Imap over NFS or OCFS" some weeks ago, but it didn't answered all my questions.] For several weeks now I'm investigating how to build a real high-performance-cluster with redundant IMAP-Nodes with Courier-IMAP. 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. The performance on the discs are bad -- iostat shows up to 100% IO-usage. 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. 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? Yes, it is possible to use an IMAP-proxy to spread the storage over several IMAP-Nodes with local storage. But that includes to many single point of failures und is very unflexible in the handling of performance peaks. Even if I would buy an expensive SAN (with fibre and all that expensive stuff) it would be necessary to use a Cluster-FS and I'm not sure, wether they will provide enough performance on many small files and I'm note sure wether they will be able to handle the caching good enough. Is it really necessary to buy a >50.000 $-SAN with >20 harddiscs just to handle some hundred Gigs of Maildir-Data?!?! Otherwise NFS is not good in caching, too... I don't know what to do any more -- *every* possibility looks bad to me. What's better? NFS? Any kind of Cluster-FS? A real SAN? RAID-5, RAID-1 oder RAID-10? Is it necessary to switch back to several non-redundant IMAP-nodes with local storage to have a better cache-performance? Or do I have to run one 4-way server with 16 GByte memory to handle *all* that connections on one single server?! I can't believe I'm the only one having this problem -- but I haven't found real answers yet. Sure, there's a lot of documentation about what is *possible*, but looks like nobody really *knows* how to handle that. Brian runs hundred of thousand accounts, he can buy a NetApp for that. But what should I do with 60.000 - 90.000 frequently used IMAP-accounts? Hope some people give me some hints about their configuration and solutions... Details about size of storage and number of clients are welcome... :-) Best regards, Peer -- Heinlein Professional Linux Support GmbH Linux: Akademie - Support - Hosting http://www.heinlein-support.de Besuchen Sie uns: CeBIT 2007: Stand G64/3 im LinuxPark! Zwangsangaben lt. §35a HGB: HRB 93818 B / Amtsgericht Berlin-Charlottenburg, Geschäftsführer: Peer Heinlein -- Sitz: Berlin ------------------------------------------------------------------------- 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
