[zfs-discuss] ZFS (and quota)

[Pawel Jakub Dawidek]

On Mon, Oct 01, 2007 at 12:57:05PM +0100, Robert Milkowski wrote:
> Hello Neil,
> 
> Thursday, September 27, 2007, 11:40:42 PM, you wrote:
> 
> 
> NP> Roch - PAE wrote:
> >> Pawel Jakub Dawidek writes:
> >>  > I'm CCing zfs-discuss at opensolaris.org, as this doesn't look like
> >>  > FreeBSD-specific problem.
> >>  > 
> >>  > It looks there is a problem with block allocation(?) when we are near
> >>  > quota limit. tank/foo dataset has quota set to 10m:
> >>  > 
> >>  > Without quota:
> >>  > 
> >>  >    FreeBSD:
> >>  >    # dd if=/dev/zero of=/tank/test bs=512 count=20480
> >>  >    time: 0.7s
> >>  > 
> >>  >    Solaris:
> >>  >    # dd if=/dev/zero of=/tank/test bs=512 count=20480
> >>  >    time: 4.5s
> >>  > 
> >>  > With quota:
> >>  > 
> >>  >    FreeBSD:
> >>  >    # dd if=/dev/zero of=/tank/foo/test bs=512 count=20480
> >>  >    dd: /tank/foo/test: Disc quota exceeded
> >>  >    time: 306.5s
> >>  > 
> >>  >    Solaris:
> >>  >    # dd if=/dev/zero of=/tank/foo/test bs=512 count=20480
> >>  >    write: Disc quota exceeded
> >>  >    time: 602.7s
> >>  > 
> >>  > CPU is almost entirely idle, but disk activity seems to be high.
> >>  > 
> >> 
> >> 
> >> Yes, as we are near quota limit, each transaction group
> >> will accept a small amount as to not overshoot the limit.
> >> 
> >> I don't know if we have the optimal strategy yet.
> >> 
> >> -r
> 
> NP> Aside from the quota perf issue, has any analysis been done as to
> NP> why FreeBSD is over 6X faster than Solaris without quotas?
> NP> Do other perf tests show a similar disparity?
> NP> Is there a difference in dd itself?
> NP> I assume that it was identical hardware and pool config.

(I don't see this e-mail in my ZFS inbox, that's why I'm replaying to
Robert's e-mail.)

Just to clarify. This was entirely different hardware. My e-mail was
__only__ about quota performance in ZFS. Please, do not try to use those
results for any other purpose.

-- 
Pawel Jakub Dawidek                       http://www.wheel.pl
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
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