dovecot - May 2014 - dsync incredibly slow

Hi!

While performing a dsync from cyrus imap to dovecot 2.2.12, dsync seems 
to stop for perhaps a minute without disk / cpu / memory activity (that 
I can see). This happens several times per sync per user so it takes an 
enormous amount of time to sync just a couple of gigs of mail.

dsync -D -v -o mail_fsync=never mirror -f -R -u user at example.com imapc:

What could possibly be the cause of this slowness? Is it protocol 
dependent or just dsync it's self?

Thanks!

W dniu 23.05.2014 10:48, Alan McGinlay pisze:
> Hi!
> 
> While performing a dsync from cyrus imap to dovecot 2.2.12, dsync seems
> to stop for perhaps a minute without disk / cpu / memory activity (that
> I can see). This happens several times per sync per user so it takes an
> enormous amount of time to sync just a couple of gigs of mail.
> 
> dsync -D -v -o mail_fsync=never mirror -f -R -u user at example.com imapc:
> 
> What could possibly be the cause of this slowness? Is it protocol
> dependent or just dsync it's self?
Hi!
"Use the strace, Luke";)
Use `strace -f -tt -T -s 512 dsync ....<other parameters>" and look
what
dsync does (when does nothing;))