Am Friday 27 May 2016 schrieb Timo Sirainen tss@iki.fi
On 05 May 2016, at 16:21, Marc Joliet marcec@gmx.de wrote: [...]
Rebooting the system would make it go away (without loss of mails), though remounting the file system should have worked, too. I tried a variety of options, but the only one that helped was to convert the mailbox from mdbox to maildir. I have not seen any pread() failures in the two weeks since. I can't really think of why Maildir format would get rid of the problem, since the dovecot.index.log files still exist and they're accessed the same way. Maybe with Maildir there are enough locks that it prevents some race condition that triggers this.
Yeah, I was somewhat surprised even without knowing that. And what do you know: two days ago I discovered pread() failures in my system log again, but this time they went away by themselves without me noticing that they even occurred:
Mai 23 18:03:45 diefledermaus dovecot[600]: imap(marcec): Error: pread() failed with file /home/marcec/.maildir/.LinuxAudio.Dev/dovecot.index.log: Input/output error Mai 23 18:03:45 diefledermaus dovecot[600]: imap(marcec): Error: pread() failed with file /home/marcec/.maildir/.LinuxAudio.Dev/dovecot.index.log: Input/output error Mai 23 18:13:57 diefledermaus dovecot[600]: imap(marcec): Error: pread() failed with file /home/marcec/.maildir/.LinuxAudio.Dev/dovecot.index.log: Input/output error Mai 23 18:13:57 diefledermaus dovecot[600]: imap(marcec): Error: pread() failed with file /home/marcec/.maildir/.LinuxAudio.Dev/dovecot.index.log: Input/output error
There were also a whole bunch affecting the same file on May 20th, but not before. I probably didn't notice those because they started shortly before I rebooted for a kernel upgrade (from gentoo-sources 4.4.10 to 4.5.5).
You could try stress testing with imaptest to see if it's easy to reproduce: http://imapwiki.org/ImapTest
I still haven't had time to do this, but haven't forgotten!
Greetings
Marc Joliet
"People who think they know everything really annoy those of us who know we don't" - Bjarne Stroustrup