cyrus.cache causes IOERROR: offset greater than cache size

[Дилян Палаузов]

Hello,

sometimes I get in the logs these messages:

Dec 01 01:30:50 mail cyrus/cyr_expire[13952]: IOERROR: offset greater than cache size 5243456 2288(0)
Dec 01 01:30:50 mail cyrus/cyr_expire[13952]: IOERROR: invalid cache record for user.u1 uid 40568 (System I/O error)
Dec 01 01:30:54 mail cyrus/cyr_expire[13952]: IOERROR: offset greater than cache size 5244620 2288(0)
Dec 01 01:30:54 mail cyrus/cyr_expire[13952]: IOERROR: invalid cache record for user.u1 uid 40569 (System I/O error)
Dec 01 01:30:55 mail cyrus/cyr_expire[13952]: IOERROR: offset greater than cache size 5247552 2288(0)
Dec 01 01:30:55 mail cyrus/cyr_expire[13952]: IOERROR: invalid cache record for user.u1 uid 40571 (System I/O error)
Dec 01 01:30:55 mail cyrus/cyr_expire[13952]: IOERROR: invalid cache record for user.u1 uid 15463 (Mailbox format
corruption detected)
Dec 01 01:30:55 mail cyrus/cyr_expire[13952]: IOERROR: cache entry truncated 1072 1835101728 2288(0)
Dec 01 01:30:55 mail cyrus/cyr_expire[13952]: IOERROR: invalid cache record for user.u1 uid 15464 (System I/O error)
Dec 01 01:30:55 mail cyrus/cyr_expire[13952]: IOERROR: cache entry truncated 2080 1131376244 2288(0)
Dec 01 01:30:55 mail cyrus/cyr_expire[13952]: IOERROR: invalid cache record for user.u1 uid 15465 (System I/O error)
Dec 01 01:30:55 mail cyrus/cyr_expire[13952]: IOERROR: offset greater than cache size (priority)3136 2288(0)
Dec 01 01:30:55 mail cyrus/cyr_expire[13952]: IOERROR: invalid cache record for user.u1 uid 15466 (System I/O error)
Dec 01 01:30:55 mail cyrus/cyr_expire[13952]: IOERROR: offset greater than cache size (priority)3976 2288(0)

Often it is connected to cyr_exipre, but not always. It can be also lmtpd.

When a cyrus.cache inconsistency is detected, the cyrus.cache is rebuild. This means reading a lot of files from the
disk.  During the reconstruction some locks are active, so effectively a lot of processes (lmtpd, imapd, httpd) are
started and all of them wait for the lock to be released.  This cache rebuild happens sometimes (perceived) very often. 
The problem is that on slow hard disks this repack operation can take hours and cyr_expire runs for hours.

My reading of the code is that new records are only appended to cyrus.cache and there is some lock ensuring the
consistency of the append operation.

I have not invested that much time in reading the code.  How is expunging supposed to happen in regards of cyrus.cache? 
Is the on unlink()ing any message the cyrus.cache always supposed to be repacked or where is the code for removing
entries from cyrus.cache?  How can I debug the cause of the invalid cache record?  

I assume that the cached records are kept, until the corresponding message file is removed from the disk.

The cyr_expire output also contains:

Dec 01 01:37:37 mail cyrus/cyr_expire[13952]: IOERROR: conversations_audit on load: /var/imap//user/s/s2.conversations
B25572d90ed3363c1
 0 (713535 1 0 0 () ((18 713534 1 1 0)) () PleaseconfirmyourNNNNregistrationnow. 0 ())

What am I supposed to do with this message?

Regards
  Дилян