[Dovecot] Documentation for "altpath" / "altmove" / ?"Alternate storage"

[William Blunn]

On 03/09/2010 15:01, Timo Sirainen wrote:
> With multi-dbox the moving is more complex, but still it only copies 
> the data in m.* files.

> Dovecot always tries to look for the u.123 or m.123 file from primary 
> storage and if it's not found there, it looks it up from alternate 
> storage. The state isn't stored in indexes. Really simple.


Thank-you for all your other comments by the way. That is all good stuff 
and appreciated.

I think the only thing I had further questions on was how alternate 
storage works with mdbox.

In http://wiki2.dovecot.org/MailboxFormat/dbox it says we have

  * dovecot.map.index* files contain the "map index"
  * m.* files contain the mail data

I think I am not clear on the "dovecot.map.index* files". Is that really 
just one file "dovecot.map.index", and the globby asterisk just 
indicates that there may be may be old versions if the file has been 
updated by being re-written?

"dovecot.map.index*" is always stored in the primary storage? (Sorry if 
it sounds like I am asking questions you've already answered. I want to 
make sure I understand it properly.)

So if we are moving mail to alternate storage, we write them into a new 
"m.*" file in the alternate storage folder containing the messages we 
want to move. So that would mean it only really makes sense for any 
given numbered "m.*" file to exist in either the primary storage or the 
alternate storage but not both?

So when Dovecot is wanting to find the next unused "m.*" file number, it 
needs to consider files in both the primary storage and alternate storage?

Bill