[Dovecot] Dovecot and Lustre FS
Hello,
Right now, I'm using Exim and a customized version of an old (10 years old) Atmail POP3 server written in Perl, with ~10000 mailboxes located on a Lustre file system. So far so good.
Though, I plan to migrate from Atmail to Dovecot, to provide our customers with IMAP support. Has anyone any experience with Dovecot on Lustre FS ?
Thanks
Christian
On Tue, 2011-09-13 at 09:59 +0100, Christian Gregoire wrote:
Right now, I'm using Exim and a customized version of an old (10 years old) Atmail POP3 server written in Perl, with ~10000 mailboxes located on a Lustre file system. So far so good.
Though, I plan to migrate from Atmail to Dovecot, to provide our customers with IMAP support. Has anyone any experience with Dovecot on Lustre FS ?
If there's just one Dovecot server accessing mails, there shouldn't be any problems. If there are more, you should read http://wiki2.dovecot.org/MailLocation/SharedDisk and stress test the same mailbox at the same time from 2+ servers using http://imapwiki.org/ImapTest
Hi Gregoire,
[..] with ~10000 mailboxes located on a Lustre file system. So far so good. This may be a bit off topic but... I thought that a lustre filesystem was not designed to store a lot of small files (e.g: due to MDS inodes)
Can you tell us more about your experience ?
Thomas
[..] with ~10000 mailboxes located on a Lustre file system. So far so good.
This may be a bit off topic but... I thought that a lustre filesystem was not designed to store a lot of small files (e.g: due to MDS inodes)
Can you tell us more about your experience ?
Hi Thomas,
We've developped our own MDA, and customized the POP server, thus for a given email, headers are stored in a MySQL database and the whole message (headers+body, mbox format) in the Lustre FS, in a directory based on the last 3 digits of its internal id (MySQL autoincrement) :
000 \_986544000 <- one email \_852125000 [...] 001 \_780284001 \_986545001 [...] [...] 999 \_489288999 \_326541999 [...]
As we only provide POP support, we reach a maximum of 2500 files per directory. Lustre version is 1.4, with one MDS and 3 OST. We have 9 SMTP/POP servers connected to the LFS.
Indeed, I have many concerns about IMAP+Lustre. For example, should I use mbox or maildir ? I'd go with the second one but really don't know how Lustre would behave with potentially tens of thousands of files in one directory (according to the Lustre FAQ, it should perform fine : http://wiki.lustre.org/index.php/FAQ_-_Sizing), but ...
I've been through some previous posts (http://dovecot.org/list/dovecot/2010-January/046106.html and http://www.dovecot.org/list/dovecot/2010-March/047673.html) and I'm also wondering whether I should switch to another FS.
Any advice ? What is the most widely used clustered FS with Dovecot ?
Thanks in avance for sharing your experience.
Christian
On 13.9.2011, at 16.58, Christian Gregoire wrote:
Indeed, I have many concerns about IMAP+Lustre. For example, should I use mbox or maildir ? I'd go with the second one but really don't know how Lustre would behave with potentially tens of thousands of files in one directory (according to the Lustre FAQ, it should perform fine : http://wiki.lustre.org/index.php/FAQ_-_Sizing), but ...
You should try Dovecot's mdbox format.
participants (3)
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Christian Gregoire
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Thomas
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Timo Sirainen