backup without stopping the imap server?

[Richard Wohlstadter]

> AFAIK the only really important data that can't be easily replaced is
> the mailbox list database.  So I do regular dumps of that file and keep
> the last several on hand in plain text format.  The database indexes in
> each user folder can be rebuilt with the reconstruct command if there
> are any corruption problems...  Remember.. the per user 'databases' are
> not storing the entire message.. only some cached metadata to make
> response times better for the client. Also.. there are two automatic
> backups of the important stuff from /var/imap if you had to use one of
> those.

We currently do the double rsync method of backing up( 1 dirty rsync, 
followed by clean rsync with imap server shutdown).  I'm doing this 
because I'm paranoid and not really clear on what databases can be 
rebuilt and how to fix corrupted database files.  We also do several 
backups of mailboxes.db( along with dumping it to text format) daily.  I 
would love to get rid of the stopping of cyrus imap server if its not 
needed since this is disruptive to clients.  Being new to cyrus, just 
not brave enough to confidentely do this yet.  I havent been able to 
find any decent docs on the database layout structure of /var/imap yet. 
  If someone could give me some explanation of what database is what and 
which can/cannot be recontructed it would help me greatly.  This is what 
I know( or think I know) so far:

mailboxes.db  - critical database containing list of all mailboxes in 
system.  Cannot be reconstructed without reliable backup copy (or text 
based copy you can import in)

deliver.db - duplicate delivery database ( if gets corrupted, can we 
delete and restart to reconstruct an empty one?? )

db directory - not sure what the heck is going into this directory.  For 
us it is berkeley database.  Can someone explain what data is in this 
directory??  Is is used in conjuction with other database files?  If 
files are deleted/corrupted in here can it be reconstructed?

The .seen and .sub databases - Looks like these per-user databases 
contain listings of what mail is read and what folders are subscribed 
to.  I assume these can be removed/reconstructed fairly easily if needed.

Any experts out there who can help me answer these questions?  Thanks


Rich
---
Cyrus Home Page: http://asg.web.cmu.edu/cyrus
Cyrus Wiki/FAQ: http://cyruswiki.andrew.cmu.edu
List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html