Hello! On 10-Jan-2002 [EMAIL PROTECTED] wrote: > Upon inexpensivety: Maybe there is another idea possible. Kimberlite > does sort of a parallel mount to a RAID on a shared SCSI bus. Maybe > there is a way here to achieve low-level distance. If you have a bus > that could be transported over some length - say: fiberchannel over ATM? - > there would be no need to bother what the OS does on it.
And also, there is a theoretical "third" way: The IMAP aggregator/proxy should connect to not one, but two boxes (the "appropriate" one for the user, and the backup of that one). Whenever there's a "modifying" command (like "DELETE"), it should execute that on both the live box and the hot backup. If a "FETCH" command arrives, that can be executed on any one of the boxes. This way, the mail stores should be synchronized. But you must also ensure that when one box disconnects, dies, and then reconnects, it has to synchronize. And, of course, incoming smtp/lmtpd mail must go to both boxes. This works somewhat like RAID1 with hard disks. Read-only operations should be normal speed (though FETCH BODY is not 100% read only, it sets the Seen flag), write could be paralellized, thus also be at about normal speed. There are catches, though. If a mail arrives at the live box, then the user deletes the "last" mail in the folder, and only then (in time) does the same mail arrive in the backup box, you have two desynched boxes. This shouldn't really happen, since the two boxes should run at the same speed, and the live box has somewhat larger load, but cases like this should be considered. | Noll Janos <[EMAIL PROTECTED]> | http://www.johnzero.hu | | "Expect the unexpected!" | ICQ# 4547866 | Linux rulez! |
