Hi,

we just upgraded our mailserver from Dovecot 1.0.15 to Dovecot 2.1.7.

We use MBOX format (due to legacy compatibility), system users, PAM+GSSAPI auth, filesystem quotas, and indexes located on a separate filesystem:

mail_location = mbox:~/mail:INBOX=~/mail/INBOX:INDEX=/var/cache/dovecot/indexes/%16Hu/%u

The 2.1.7 configuration files have been rewritten based on default templates instead of converting it from 1.0.15.

The server has ~8000 mailboxes and about ~2000 simultaneous IMAP/POP active connexions.

The problem is:

• indexes seem to be rebuilt: first IMAP/POP connexion for each user thows lots of error messages in the log, and the global index size decreases.

Example error log: Nov 19 08:56:38 myhost dovecot: imap(myuser): Error: Cached message size larger than expected (27884 > 27855) Nov 19 08:56:38 myhost dovecot: imap(myuser): Error: Corrupted index cache file /var/cache/dovecot/indexes/4/myuser/.imap/INBOX/dovecot.index.cache: Broken physical size for mail UID 4414 Nov 19 08:56:38 myhost dovecot: imap(myuser): Error: Cached message size larger than expected (27884 > 27855) Nov 19 08:56:38 myhost dovecot: imap(myuser): Error: Corrupted index cache file /var/cache/dovecot/indexes/4/myuser/.imap/INBOX/dovecot.index.cache: Broken physical size for mail UID 4414 Nov 19 08:56:38 myhost dovecot: imap(myuser): Error: Cached message size larger than expected (27884 > 27855) Nov 19 08:56:38 myhost dovecot: imap(myuser): Error: Corrupted index cache file /var/cache/dovecot/indexes/4/myuser/.imap/INBOX/dovecot.index.cache: Broken physical size for mail UID 4414 Nov 19 08:56:38 myhost dovecot: imap(myuser): Error: Cached message size larger than expected (27884 > 27855) Nov 19 08:56:38 myhost dovecot: imap(myuser): Error: Corrupted index cache file /var/cache/dovecot/indexes/4/myuser/.imap/INBOX/dovecot.index.cache: Broken physical size for mail UID 4414 Nov 19 08:56:38 myhost dovecot: imap(myuser): Error: copy: i_stream_read() failed: Input/output error Nov 19 08:56:38 myhost dovecot: imap(myuser): Error: Cached message size larger than expected (27884 > 27855) Nov 19 08:56:38 myhost dovecot: imap(myuser): Error: Corrupted index cache file /var/cache/dovecot/indexes/4/myuser/.imap/INBOX/dovecot.index.cache: Broken physical size for mail UID 4414

• load average is extremely high (more than 10x the usual one), resulting from an significant increase of disk I/O, and for now (4h after the "monday rush") this doesn't seem to decrease.

Questions:

• are 1.05 indexes supposed to be backward compatible with Dovecot 2.1.7 ?
• are there some technical reasons which could explain the increase of disk I/O, apart from index rebuild ?

-- Benoit BRANCIARD Service InfraStructures (SIS) - Direction du Système d'Information (DSI) Université Paris 1 Panthéon-Sorbonne Centre Pierre Mendès France B 406 - 90, rue de Tolbiac - 75634 Paris cedex 13 - France Tél : +33 1 44 07 89 68 - Fax : +33 1 44 07 89 66 Accueil tél. : +33 1 44 07 89 65 Assistance : assistance-dsi@univ-paris1.fr Web : http://dsi.univ-paris1.fr

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