(Note: I am not subscribed to this ML, so please be sure to CC me in replies.)
Hello,
I see a strange bug when running dovecot under btrfs with a mailbox in mdbox
format. At some point, which can take a few minutes or more than a day,
dovecot starts logging pread() failures, like so:
Apr 02 23:43:42 thetick dovecot[570]: imap(marcec): Error: pread() failed with
file /home/marcec/.mdbox/mailboxes/LinuxAudio/User/dbox-
Mails/dovecot.index.log: Input/output error
These would trigger when getmail runs (which in turn is configured to use
dovecot-lda). It's only ever the *.index.log files, and it would usually
happen to the same one many times in a row. To demonstrate, this is the full
list of unique pread() failures on one host (my desktop PC):
# journalctl -u dovecot -p 3 -o cat | sort -u | grep pread
imap(marcec): Error: pread() failed with file
/home/marcec/.mdbox/mailboxes/BTRFS/dbox-Mails/dovecot.index.log: Input/output
error
imap(marcec): Error: pread() failed with file
/home/marcec/.mdbox/mailboxes/Gentoo/User/dbox-Mails/dovecot.index.log:
Input/output error
imap(marcec): Error: pread() failed with file
/home/marcec/.mdbox/mailboxes/INBOX/dbox-Mails/dovecot.index.log: Input/output
error
imap(marcec): Error: pread() failed with file
/home/marcec/.mdbox/mailboxes/LinuxAudio/User/dbox-Mails/dovecot.index.log:
Input/output error
imap(marcec): Error: pread() failed with file
/home/marcec/.mdbox/mailboxes/Newsletters/dbox-Mails/dovecot.index.log:
Input/output error
imap(marcec): Error: pread() failed with file
/home/marcec/.mdbox/mailboxes/SCons/User/dbox-Mails/dovecot.index.log:
Input/output error
imap(marcec): Error: pread() failed with file
/home/marcec/.mdbox/storage/dovecot.map.index.log: Input/output error
and on the current host (a home server):
# journalctl -u dovecot -p 3 -o cat | sort -u | grep pread
imap(marcec): Error: pread() failed with file
/home/marcec/.mdbox/mailboxes/Privat/dbox-Mails/dovecot.index.log:
Input/output error
imap(marcec): Error: pread() failed with file
/home/marcec/.mdbox/storage/dovecot.map.index.log: Input/output error
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 originally wrote to the btrfs ML, see the thread at [0], in particular my
messages [1] and [2], for additional details, including references to what
little I could find on the web. However, nothing much came of that thread, so
I am now posting here.
My dovecot configuration:
# doveconf -n
# 2.2.19: /etc/dovecot/dovecot.conf
# Pigeonhole version 0.4.9 (357ac0a0e68b+)
# OS: Linux 4.4.8-gentoo x86_64 Gentoo Base System release 2.2
auth_mechanisms = plain login
mail_location = maildir:~/.maildir
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope encoded-character
vacation subaddress comparator-i;ascii-numeric relational regex imap4flags
copy include variables body enotify environment mailbox date index ihave
duplicate
namespace inbox {
inbox = yes
location =
mailbox Drafts {
special_use = \Drafts
}
mailbox Junk {
special_use = \Junk
}
mailbox Sent {
special_use = \Sent
}
mailbox "Sent Messages" {
special_use = \Sent
}
mailbox Trash {
special_use = \Trash
}
prefix =
separator = /
}
passdb {
args = *
driver = pam
}
plugin {
sieve = file:~/.sieve;active=~/.dovecot.sieve
}
postmaster_address = root at diefledermaus
protocols = imap sieve
service imap-login {
inet_listener imap {
port = 10087
}
inet_listener imaps {
port = 10887
}
}
ssl = required
ssl_cert = </etc/ssl/dovecot/dovecot.pem
ssl_key = </etc/ssl/dovecot/dovecot.key
userdb {
driver = passwd
}
protocol lda {
auth_socket_path = /var/run/dovecot/auth-master
mail_plugins = sieve
}
protocol sieve {
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope encoded-character
vacation subaddress comparator-i;ascii-numeric relational regex imap4flags
copy include variables body enotify environment mailbox date
}
I used to use claws-mail, then switched to KMail in September 2015. So the
errors happened with both clients.
[0] http://thread.gmane.org/gmane.comp.file-systems.btrfs/49637
[1] http://article.gmane.org/gmane.comp.file-systems.btrfs/49647
[2] http://article.gmane.org/gmane.comp.file-systems.btrfs/55552
Greetings
--
Marc Joliet
--
"People who think they know everything really annoy those of us who know we
don't" - Bjarne Stroustrup
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