[Dovecot] dsync is SLOW compared to rsync

[Jeff Gustafson]

On Thu, 2012-03-29 at 02:12 +0300, Timo Sirainen wrote:
> On 22.3.2012, at 23.25, Jeff Gustafson wrote:
> 
> > [root at n24 bu]# time dsync backup -u testuser at domain.com \
> > mdbox:/home/bu/testuser
> > 
> > real    1m9.519s
> > user    1m7.592s
> > sys     0m1.126s
> 
> Most of the time is spent on usermode CPU code. I doubt the problem is dsync itself, most likely the problem is mdbox's saving code. Or possibly index/cache code. Try the same dsync backup for:
> 
>  - mbox:/tmp/mbox
>  - mbox:/tmp/mbox:INDEX=MEMORY
>  - sdbox:/tmp/sdbox

	My tests show that maildir to mdbox or sdbox backup/conversions take
about the same length in time. I noticed maybe a second or two
difference between mdbox and sdbox). On a 3.1GB mailbox either one took
about 6 minutes. Rsync, on the other hand, took less than a minute. I
will re-run the tests with a maildir to maildir backup and see how long
it takes.

			...Jeff