I realize it's hard to be precise about this, but does anyone have a feel or rule of thumb for a couple of aspects of indexing overhead? 1. Proportionally, how much space does it take for all 4 files? If I want to give my users a quota of 100 MB for messages, how much real space should I plan for so that I won't run out of space for indexing? 2. What's the overhead in rebuilding index files? Suppose I use an LDA other than dovecot, so at least the INBOX index is frequently getting out of date. Does it cost much (in CPU, memory, and disk IO) to rebuild the index files? (I'm using maildir.)
WJCarpenter spake the following on 8/22/2007 9:55 PM:> I realize it's hard to be precise about this, but does anyone have a > feel or rule of thumb for a couple of aspects of indexing overhead? > > 1. Proportionally, how much space does it take for all 4 files? If I > want to give my users a quota of 100 MB for messages, how much real > space should I plan for so that I won't run out of space for indexing? > > 2. What's the overhead in rebuilding index files? Suppose I use an > LDA other than dovecot, so at least the INBOX index is frequently > getting out of date. Does it cost much (in CPU, memory, and disk IO) > to rebuild the index files? (I'm using maildir.) > >You can always put the indexes in non-quota space like var. That way the indexes don't get counted against the users files, and won't get corrupted if a user goes over quota. -- MailScanner is like deodorant... You hope everybody uses it, and you notice quickly if they don't!!!!
On Wed, 2007-08-22 at 21:55 -0700, WJCarpenter wrote:> I realize it's hard to be precise about this, but does anyone have a > feel or rule of thumb for a couple of aspects of indexing overhead? > > 1. Proportionally, how much space does it take for all 4 files? If I > want to give my users a quota of 100 MB for messages, how much real > space should I plan for so that I won't run out of space for indexing?It really depends on what IMAP client is being used. Something like 10-20% maybe.> 2. What's the overhead in rebuilding index files? Suppose I use an > LDA other than dovecot, so at least the INBOX index is frequently > getting out of date. Does it cost much (in CPU, memory, and disk IO) > to rebuild the index files? (I'm using maildir.)Indexes aren't normally "rebuilt", they're "updated". And the update overhead is practically nothing with maildir. I just wrote this: http://wiki.dovecot.org/LDA/Indexing -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 189 bytes Desc: This is a digitally signed message part URL: <http://dovecot.org/pipermail/dovecot/attachments/20070824/09a59b7f/attachment-0002.bin>
> Indexes aren't normally "rebuilt", they're "updated". And the update > overhead is practically nothing with maildir. > > I just wrote this: http://wiki.dovecot.org/LDA/IndexingHi Timo... So, if I understand this correctly, if I'm using maildir, I could use exim to do the local delivery instead of dovecot's LDA, and the index update wouldn't such a big problem? In my case, local delivery and the real imap servers are in different boxes, so by having exim doing the local delivery, I'd avoid a dovecot install in the local delivery boxes. And of course, exim doesn't have to spawn dovecot's delivery agent on every siingle piece of mail. Also, are there any drawbacks of using exim to do the local delivery? Thanks a bunch, g.