immense delayed write to file system (ZFS and UFS2), performance issues

[Andriy Gapon]

on 27/01/2010 22:26 Tommi Lätti said the following:
> Seems that the performance is indeed atrocious. I recently (like 2
> days ago) had to rescue my zfs pool under opensolaris to spare disks.
> The performance under OpenSol was what I was expecting, 70MB/s reading
> and writing at the same time.
> 
> Now that I'm restoring the stuff back under FreeBSD 8.0-p2 it seems
> that first the array reads from the source disk and then stops reading
> and decides to empty the buffer to the destination. There's usually a
> 2 second pause and after that it goes back to reading. There seems to
> be something really wrong with this, fbsd zfs implementation seems to
> be unable to move data between 2 zfs pools writing and reading
> simultaneously...
> 
> I think I'll just boot back to opensol and do the transfers there.

I've been seeing things like this too.
Also, when copying between UFS and ZFS.

-- 
Andriy Gapon