Hi, I did some experiments with dovecot on a glusterfs on the active nodes without a director. So I had concurrent access to the files. With the help of the available documentation about NFS and fcntl locks I managed to find out the following: With the plain mbox format dovecot seems to apply and to honor the fcntl locks. But since this format is not used any more in real setups, it is useless. With mdbox and maildir format I could reliably crash my mail storage just by delivering mails to the both dovecots via LMTP to the same user. In maildir dovecot seems not the set / respect the fnctl locks of the index file. dotlocks do not seems to work either with mdbox. So I think the only solution os to use a director in a real world setup. Or is there any non-obvious trick that I did not check? I think it would be really nice if dovecot could use glusterfs for realy scalable postbox servers. Mit freundlichen Gr??en, Michael Schwartzkopff -- [*] sys4 AG http://sys4.de, +49 (89) 30 90 46 64, +49 (162) 165 0044 Franziskanerstra?e 15, 81669 M?nchen Sitz der Gesellschaft: M?nchen, Amtsgericht M?nchen: HRB 199263 Vorstand: Patrick Ben Koetter, Marc Schiffbauer Aufsichtsratsvorsitzender: Florian Kirstein
On 1/13/15, Michael Schwartzkopff <ms at sys4.de> wrote:> Hi, > > I did some experiments with dovecot on a glusterfs on the active nodes > without > a director. So I had concurrent access to the files. > > With the help of the available documentation about NFS and fcntl locks I > managed to find out the following: > > With the plain mbox format dovecot seems to apply and to honor the fcntl > locks. But since this format is not used any more in real setups, it is > useless. > > With mdbox and maildir format I could reliably crash my mail storage just by > > delivering mails to the both dovecots via LMTP to the same user. In maildir > > dovecot seems not the set / respect the fnctl locks of the index file. > dotlocks > do not seems to work either with mdbox. > > So I think the only solution os to use a director in a real world setup. Or > is > there any non-obvious trick that I did not check?Interesting, we use NFSv3 dovecot LDA with maildir, we have at present two dozen front end SMTP servers (using dovecot-lda) and some, hrmm we added a few more over Christmas, so I think about 32 pop3 servers, but with only 4 imap servers incl webmail (IMAP is not heavily used here due to government spy laws) talking to NAS storage server backend, *we do not use director* at all and has never been an issue. Director IIRC solves the problem of IMAP inconsistency, but we never see advantage when we tested, no doubt it solves some fancy setup problem, but since director can not help with pop3, it was not worth the hassle. never had any problems with webmail either, load balancers seem to look after it well We did see lot of people with issues with LMTP, but we never saw these with lda.> I think it would be really nice if dovecot could use glusterfs for realy > scalable postbox servers.There was some nasty problems with that with cyrus, so much so, most uni's here who used that moved to a NAS backend and no one has whinged since :->
Am Dienstag, 13. Januar 2015, 21:40:34 schrieb Nick Edwards:> On 1/13/15, Michael Schwartzkopff <ms at sys4.de> wrote: > > Hi, > > > > I did some experiments with dovecot on a glusterfs on the active nodes > > without > > a director. So I had concurrent access to the files. > > > > With the help of the available documentation about NFS and fcntl locks I > > managed to find out the following: > > > > With the plain mbox format dovecot seems to apply and to honor the fcntl > > locks. But since this format is not used any more in real setups, it is > > useless. > > > > With mdbox and maildir format I could reliably crash my mail storage just > > by > > > > delivering mails to the both dovecots via LMTP to the same user. In > > maildir > > > > dovecot seems not the set / respect the fnctl locks of the index file. > > dotlocks > > do not seems to work either with mdbox. > > > > So I think the only solution os to use a director in a real world setup. > > Or > > is > > there any non-obvious trick that I did not check? > > Interesting, we use NFSv3 dovecot LDA with maildir, we have at present > two dozen front end SMTP servers (using dovecot-lda) and some, hrmm we > added a few more over Christmas, so I think about 32 pop3 servers, > but with only 4 imap servers incl webmail (IMAP is not heavily used > here due to government spy laws) talking to NAS storage server > backend, *we do not use director* at all and has never been an issue. > Director IIRC solves the problem of IMAP inconsistency, but we never > see advantage when we tested, no doubt it solves some fancy setup > problem, but since director can not help with pop3, it was not worth > the hassle. never had any problems with webmail either, load balancers > seem to look after it wellYes. NFS has its own locking. I wanted to use plain glusterfs client without the detour of NFS. Thanks for your hint. Mit freundlichen Gr??en, Michael Schwartzkopff -- [*] sys4 AG http://sys4.de, +49 (89) 30 90 46 64, +49 (162) 165 0044 Franziskanerstra?e 15, 81669 M?nchen Sitz der Gesellschaft: M?nchen, Amtsgericht M?nchen: HRB 199263 Vorstand: Patrick Ben Koetter, Marc Schiffbauer Aufsichtsratsvorsitzender: Florian Kirstein
* Michael Schwartzkopff schrieb am 13.01.15 um 09:32 Uhr:>Hi, > >I did some experiments with dovecot on a glusterfs on the active nodes without >a director. So I had concurrent access to the files. > >With the help of the available documentation about NFS and fcntl locks I >managed to find out the following: > >With the plain mbox format dovecot seems to apply and to honor the fcntl >locks. But since this format is not used any more in real setups, it is >useless.Did you try sdbox, too? -- [*] sys4 AG http://sys4.de, +49 (89) 30 90 46 64 Franziskanerstra?e 15, 81669 M?nchen Sitz der Gesellschaft: M?nchen, Amtsgericht M?nchen: HRB 199263 Vorstand: Patrick Ben Koetter, Marc Schiffbauer Aufsichtsratsvorsitzender: Florian Kirstein
Am Dienstag, 13. Januar 2015, 13:30:15 schrieb Marc Schiffbauer:> * Michael Schwartzkopff schrieb am 13.01.15 um 09:32 Uhr: > >Hi, > > > >I did some experiments with dovecot on a glusterfs on the active nodes > >without a director. So I had concurrent access to the files. > > > >With the help of the available documentation about NFS and fcntl locks I > >managed to find out the following: > > > >With the plain mbox format dovecot seems to apply and to honor the fcntl > >locks. But since this format is not used any more in real setups, it is > >useless. > > Did you try sdbox, too?not yet. Will try as soon as I find some time. Mit freundlichen Gr??en, Michael Schwartzkopff -- [*] sys4 AG http://sys4.de, +49 (89) 30 90 46 64, +49 (162) 165 0044 Franziskanerstra?e 15, 81669 M?nchen Sitz der Gesellschaft: M?nchen, Amtsgericht M?nchen: HRB 199263 Vorstand: Patrick Ben Koetter, Marc Schiffbauer Aufsichtsratsvorsitzender: Florian Kirstein
Am Dienstag, 13. Januar 2015, 13:30:15 schrieb Marc Schiffbauer:> * Michael Schwartzkopff schrieb am 13.01.15 um 09:32 Uhr: > >Hi, > > > >I did some experiments with dovecot on a glusterfs on the active nodes > >without a director. So I had concurrent access to the files. > > > >With the help of the available documentation about NFS and fcntl locks I > >managed to find out the following: > > > >With the plain mbox format dovecot seems to apply and to honor the fcntl > >locks. But since this format is not used any more in real setups, it is > >useless. > > Did you try sdbox, too?sdbox also gives an error: lmtp(30999, user1 at example.net): Error: sdbox: /srv/mail/user1 at example.net/mailboxes/INBOX/dbox-Mails/u.69 already exists, rebuilding index Mit freundlichen Gr??en, Michael Schwartzkopff -- [*] sys4 AG http://sys4.de, +49 (89) 30 90 46 64, +49 (162) 165 0044 Franziskanerstra?e 15, 81669 M?nchen Sitz der Gesellschaft: M?nchen, Amtsgericht M?nchen: HRB 199263 Vorstand: Patrick Ben Koetter, Marc Schiffbauer Aufsichtsratsvorsitzender: Florian Kirstein