[Dovecot] Mail deduplication

[Timo Sirainen]

On 30.4.2013, at 12.22, Jan-Frode Myklebust <janfrode at tanso.net> wrote:

> Wasn't there also some issue with cleanup of attachments ? Not being able
> to delete the last copy, or something. I did some testing of using SIS on a
> backup dsync destination a year (or two) ago, and got quite confused..
> Don't quite remember the problems I had, but I did lose confidence in it
> and decided having the attachement together with the messages felt safest.
> 
> I would also love to hear from admins using it on large scale (100K+ active
> users). Maybe we should reconsider using it..

I'm not aware of any bugs in SIS, but yeah, it can be a bit complicated. If you do things like dsync where destination is also mdbox/sdbox, it's going to keep using the same SIS directory and updating the refcounts, which you probably don't want for backups / temp directories (solution: give different parameters to the two sides of dsync where the other side disables SIS).