doveadm backup fails (compromised single attachment storage)

Webert de Souza Lima webert.boss at
Thu Sep 29 12:33:39 UTC 2016


A couple of months ago I had a problem with Single Attachment Storage after
infrastructure migration;

All mailboxes were rsynced to another filesystem, and that may have broken
Single Attachment Storage. Many, many (if not all) mailboxes show the below
logs on dovecot:

imap(foo at Error: read(attachments-connector(zlib(/dovecotdir/mail/ failed:
b/l]) failed: open(/dovecotdir/attach/
failed: No such file or directory

When that happens, the MUA keeps syncing forever.

Now, I need to migrate all mailboxes (again) to another dovecot instance
(with no SAS), which works perfectly for new users but when I try to
migrate users from my current dovecot server for this new server, I get
such errors again, and I can't migrate:

2016-09-29T12:20:50.995934059Z Sep 29 12:20:50 dsync-server(foo at
Error: dsync(cf7d091311eb):
failed: read(/dovecotdir/attach/[base64:18
b/l]) failed: open(/dovecotdir/attach/
failed: No such file or directory (last sent=mail, last recv=mail_request

Is there a way to fix the attachments problem? (I know I can't recover such
files, that's Ok)
Is there a way to migrate (dsync backup) ignoring such problems?

Thanks in advance.

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