[Dovecot] keeping indexes in tmpfs
tss at iki.fi
Mon Apr 16 17:52:49 EEST 2007
On Mon, 2007-04-16 at 10:41 -0400, Justin McAleer wrote:
> Ok, I'll give more detail about the setup. I plan to use the convert
> plugin to migrate from CommuniGate to dovecot for our ~160,000 accounts.
> We will probably migrate one domain at a time, letting users basically
> migrate their mail at first login. But, we will also go through all the
> domain's accounts logging in to pop3 just to ensure everything gets moved.
OK, that also causes it to read the mailboxes and save the message sizes
to cache files.
> So, for testing, I've copied a few of our domains' mail spools over to
> the test server and started a script that forks and goes through all
> their accounts and simply logs in to pop3 and waits for a message list
> to come back. We have the maildirs being stored on an NFS mount though,
> and indexes on localdisk, so the only localdisk activity was logging and
And reading the mail spools? :)
> I'll try setting both of those options and see how much
> difference it makes, although I'm not sure that losing mail upon server
> reset is acceptible for us (disabling fsync).
It could be done pretty easily only for index files by modifying the
sources. I guess another option should be added for this.
> >> Anyway, Timo and others, do you have any thoughts about keeping indexes
> >> on a tmpfs partition? I realize the obvious issues with this: running
> >> out of space, and the fact that the partition is lost on reboot.
> > I think memory would be better used for keeping mailbox data cached
> > that's actually useful at the time.
> Perhaps, but one way or another, we apparently cannot use a simple
> localdisk for indexes. So, the options are either memory or some sort of
> raid setup. Since we use maildirs, isn't the disk cache aspect less of a
Depends on how mailboxes are accessed. If message contents are read only
once then I guess it doesn't matter. Probably the worst offender here is
SEARCH TEXT/BODY command.
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