On Thu, Jan 25, 2007 at 08:56:51AM +0000, Brian Candler wrote: > As for OCFS: I have no experience. I see that v2 is supposed to have POSIX > filesystem semantics, which v1 didn't; Maildir relies heavily on POSIX > semantics, in particular atomic moves of files between directories.
A point to note from http://oss.oracle.com/projects/ocfs2/dist/documentation/cheap_clustering.pdf " * No indexed directories yet - Keep directory sizes small to medium" So if a user stores 10,000 messages in one folder, you may find performance issues. Apparently this is going to be fixed in a later version of OCFSv2 And another point to note from http://oss.oracle.com/projects/ocfs2/dist/documentation/fasheh.pdf "OCFS2 has a cluster wide rename lock, for the same reason that the VFS has s_vfs_rename_mutex - certain combinations of rename(2) can cause deadlocks, even between multiple nodes. A comment in ocfs2_rename() is instructive: /* Assume a directory hierarchy thusly: * a/b/c * a/d * a,b,c, and d are all directories. * * from cwd of âaâ on both nodes: * node1: mv b/c d * node2: mv d b/c * * And thatâs why, just like the VFS, we need a * file system rename lock. */" Maildir operations involve a *lot* of renames (moving delivered message from tmp/ to new/; moving new mail from new/ to cur/; setting flags on the filename when it is in cur/). Depending on how this is implemented in OCFS2, you may find yourself with a lot of global lock contention. Having said all this: OCFS2 looks very neat. You will of course need a very good performance SAN backend to it :-) I guess the point is, you should do performance testing on whichever solution you choose. 'postal' and 'rabid' are tools for generating large volumes of SMTP and POP3 operations - see http://www.coker.com.au/postal/ Regards, Brian. ------------------------------------------------------------------------- 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
