[Dovecot] extremely slow delete/move operations?
jpeacock at rowman.com
Mon Jan 30 20:24:40 EET 2006
Gregory K. Ruiz-Ade wrote:
> The primary difference seems to be that we're using NFS here
> Mailbox formats are mbox.
Those are the two most important pieces of information in your message
(IMHO). mbox is always slower than maildir when the filesize exceeds
the operating memory for the server (i.e. it cannot be mmapped). NFS
will always be slower than "local" access, even on NetApp's supposed
'high-performance' NFS. The combination is deadly, since every message
stored in Trash requires copying the entire mbox file and appending the
new message, then deleting the original and renaming the new file in its
Then there is the additional performance drag caused by Dovecot
rewriting the index, as well as Thunderbird (which you should really
upgrade to 1.5) keeping its local index up to date. You can confirm
this by emptying your trash folder and seeing if the performance changes
(which I am confident it will).
There are three things you can do to improve performance:
1) Upgrade to Dovecot 1.0 stable (or even Beta2);
2) Switch to Maildir (instead of mbox);
3) Install a SAN (instead of the NFS mounted NAS).
The last is the only one that costs you hard capital; the other two only
involve your time, which as we all know, doesn't count. ;-)
Director of Information Research and Technology
Rowman & Littlefield Publishing Group
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Lanham, MD 20706
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