How much memory in the V210 ?
UFS will recycle it's own pages while creating files that
are big. ZFS working against a large heap of free memory will
cache the data (why not?). The problem is that ZFS does not
know when to stop. During the subsequent memory/cache
reclaim, ZFS is potentially not very efficient at keeping up
with the file creation process (just a hypothesis here). See:
6488341 ZFS should avoiding growing the ARC into trouble
(http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6488341)
<disclaimer: a common mistake is to view the bug du jour
everywhere, So it's just a lead for investigations.>
It's interesting that zpool iostat reports 50MB/s
but 6GB in 3.13 sec is 31MB/sec. Is the recordsize tuned ?
is compression on ?
-r
eric kustarz writes:
> Jay Grogan wrote:
> > Ran 3 test using mkfile to create a 6GB on a ufs and ZFS file system.
> > command ran mkfile -v 6gb /ufs/tmpfile
> >
> > Test 1 UFS mounted LUN (2m2.373s)
> > Test 2 UFS mounted LUN with directio option (5m31.802s)
> > Test 3 ZFS LUN (Single LUN in a pool) (3m13.126s)
> >
> > Sunfire V120
> > 1 Qlogic 2340
> > Solaris 10 06/06
> >
> > Attached to Hitachi 9990 (USP) LUNS are Open L's at 33.9 GB, plenty of
> > cache on the HDS box disk are in a Raid5 .
> >
> > New to ZFS so am I missing something the standard UFS write bested ZFS by
> > a minute. ZFS iostat showed about 50 MB a sec.
> >
>
> Hmm, something doesn't seem right. From my previous experiments back in
> the day, ZFS was slightly faster than UFS:
> http://blogs.sun.com/erickustarz/entry/fs_perf_102_filesystem_bw
>
> And i re-ran this on 10/31 nevada non-debug bits:
>
> ZFS:
> # /bin/time sh -c 'lockfs -f .; mkfile 6g 6g.txt; lockfs -f .'
>
> real 1:45.8
> user 0.0
> sys 16.5
> #
>
> UFS write cache disabled:
> # /bin/time sh -c 'lockfs -f .; mkfile 6g 6g.txt; lockfs -f .'
>
> real 1:57.4
> user 0.9
> sys 39.3
> #
>
> UFS write cache enabled:
> # /bin/time sh -c 'lockfs -f .; mkfile 6g 6g.txt; lockfs -f .'
>
> real 1:57.1
> user 0.9
> sys 39.4
> #
>
> The big difference of course being our hardware. I'm using a V210 (2
> way sparc) with a single disk - no NVRAM.
>
> So what is a "LUN" in your setup? and there's NVRAM in the HDS box?
>
> What does your iostat output look like when comparing UFS vs. ZFS? I'm
> wondering if we're hitting the problem where we send the wrong flush
> write cache command down and we're actually flushing the NVRAM every
> txg, when the storage should be smart enough to ignore the flush.
>
> eric
>
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