[Dovecot] Architecture for large Dovecot cluster

[Joseph Tam]

Sven Hartge <sven at svenhartge.de> wrote:

> Interesting datapoint: NetApp Deduplication did only recover about 1% of
> storage space with mdbox-based mail storage, while on an maildir-based
> mail storage, the rate was about 15%. (This was tested with a copy of
> real user data, so is accurate for my workload.)

Just a guess, but I expect the difference is because NetApp de-dupes by
checksumming blocks and mark whole blocks as duplicates if they have
the same checksum.

The message body has the same block offset in maildir (i.e. the start of
a message is at byte 0), whereas mdbox might align message body anywhere
in a block, so you might have 512 different block configurations for
the same message.

I don't know whether message alignment would be a worthwhile optimization
for mdbox.

Joseph Tam <jtam.home at gmail.com>