Could even be memory. I had once on an office machine a faulty memory module (without ecc), and it caused the md5sum from files on truecrypt usb backup drives to change constantly. Removed the module, and no more issues.
Something to try, this all could be happening because of underlying disk failure on the array it is running on. If this is a VM, can you move the operation to another host or data store to rule out hardware issues?
On 2/2/2023 9:19 AM, Stuart Henderson wrote:
On 2023-02-01, Tim Evers te-ml-ext@artfiles.de wrote:
I run a fairly large Dovecot Installation (around 100k mailboxes) on several servers.
gzip compression is on.
Every once in a while I get the dreaded "cache corruption" messages in the log:
Error: Corrupted record in index cache file /[redacted]/Maildir/dovecot.index.cache: UID 3868: Broken physical size in mailbox INBOX:
read(zlib(/[redacted]/Maildir/cur/1674129792.M797543P21755.node2,S=8099,W=8276 :2,))
failed: Cached message size smaller than expected (2877 < 8099, box=INBOX, UID=3868)
Error: Corrupted record in index cache file /[redacted]/Maildir/dovecot.index.cache: UID 3875: Broken physical size in mailbox INBOX:
read(zlib(/[redacted]/Maildir/cur/1674212201.M985809P29112.node2,S=13907,W=141 21:2,))
failed: Cached message size smaller than expected (5533 < 8192, box=INBOX, UID=3875)
The first entry shows 2877 (size on disk) vs. 8099 (real size unzipped, also in the filename: S=8099).
The second entry shows 5533 (size on disk) vs. 8192 - this is not correct in any way. Size on disk is 13907 as noted in the filename.
Both mails were delivered trough LMTP and retrieved by the POP3 service.
Anyone with an idea what might be happening here? I've read all available info in the doc and in the previous discussions / bug reports, but nothing seems to match my case. And where does that 8192 come from - it looks suspicious?
Version is 2.3.7.2 (Ubuntu 20.04) 2.3.7.2 is rather old now. There were definitely fixes regarding compression around the 2.3.10-2.3.12 timeframe or thereabouts (I forget all the details but it took a release or two before some remaining issues were sorted out after changes in the area). I'd be looking to get it updated to a current version first.