From: <c.reynolds_at_email.protected>
Date: Tue, 25 Aug 2009 14:20:42 +0800

Nice work Jamie.

Judging by these results it does look like xfs would probably be the way to go.

Of course ext4 will be available pretty soon and should address the
performance problems in ext3, but for now xfs does seem the best
option.

cheers,
Cormac.

2009/8/25 Chris Phillips <Chris.Phillips_at_csiro.<!--nospam-->au>:
>Yes but the problem with ext2 is that if the disk is uncleanly unmounted you
>have to wait ages to run fsync.
>
>
>xfs seems to be the speed of ext2 and not the problems. Reformatting changes
>are a trivial change to the scripts.
>
>
>Cheers
>Chris
>
>On 25/08/2009, at 4:12 PM, Claire Hotan wrote:
>
>>Hi all,
>>
>>Not necessarily relevant but Randall felt that xfs and raiding didn't get
>>on as well as ext2, so our internal feelings here were to simply turn off
>>the journalling option in the formatting script, thus returning things to
>>ext2, which means no significant changes but a probable potential speed up.
>>
>>I'd be interested to know which disk sets Jamie used, were they
>>"reliable"? The older disks seem more inclined to producing bigbuff errors
>>at high speed, though there's also been problems with Curtin 750s. In
>>general ATNF or CURT 500s that haven't had any history of disk failures seem
>>to be best able to cope with high speeds, but if we have some disk sets that
>>are marginal, then maybe switching to ext2 would fix those problems.
>>
>>Of course if people want to use xfs that's cool too, but from a scripts
>>perspective switching to ext2 would involve virtually no work, and we know
>>everything works just fine with ext2 because it's what we used until a year
>>ago.
>>
>>Just my two bob.
>>
>>cheers
>>
>>Claire
>>
>>
>>-----Original Message-----
>>From: owner-vlbiobs_at_atnf.<!--nospam-->csiro.au on behalf of Chris Phillips
>>Sent: Tue 8/25/2009 1:58 PM
>>To: Jamie Stevens
>>Cc: VLBI observers
>>Subject: Re: LBA recorder disk speed tests
>>
>>Thanks for doing this
>>
>>Of course these results show *any* of the filesystems can cope with
>>512 Mbps....
>>
>>Maybe we should try xfs for the next session. First we would need to
>>try some tests such as swapping disks after recording etc.
>>
>>Cheers
>>Chris
>>
>>On 25/08/2009, at 3:48 PM, Jamie Stevens wrote:
>>
>>>> Hi all,
>>>>
>>>> I've completed some diskspeed tests on cavsi1 using ext3, ext2 and xfs
>>>> filesystems. I did all tests using filesizes that would have been
>>>> generated by an experiment running at 512 Mbit/s; some with 10s files,
>>>> others with 60s files.
>>>>
>>>> I've attached two postscript files to this email. Each shows the
>>>> results
>>>> of the 9 tests I did, and each file corresponds to tests run on one
>>>> side
>>>> of the Xraid (all tests were performed on both Xraid sides to ensure
>>>> consistency).
>>>>
>>>> The results show that ext3 is quite a lot slower than ext2 or xfs,
>>>> even
>>>> when tuned for performance. xfs has the highest average speed, with
>>>> ext2
>>>> not far behind. It doesn't appear that changing the filesize has much
>>>> effect on the average speed the disks can sustain.
>>>>
>>>> One of the most important things is the minimum speed. The bigbuffer
>>>> will start to fill if the speed falls below the required recording
>>>> rate,
>>>> and this will lead to bigbuf skips if the disks don't catch up in
>>>> time.
>>>> ext3 filesystems have a very low minimum speed, as do ext2 filesystems
>>>> with 10s files. But with 60s files, both ext2 and xfs do not drop much
>>>> below 500 Mbit/s, and xfs can keep its minimum rate up even with 10s
>>>> files.
>>>>
>>>> cheers
>>>> Jamie
>>>>
>>>> <
>>>> lba_speedtests_xraid0
>>>> .ps.gz><lba_speedtests_xraid1.ps.gz><Jamie_Stevens.vcf>
>>
>>------------------------------------------------------------
>>Chris Phillips
>>CSIRO ATNF     eVLBI project scientist
>>Office: (+61) (0)2 93724608      Mobile: (+61) (0)439487601
>>
>>
>>
>>
>>
>
>------------------------------------------------------------
>Chris Phillips
>CSIRO ATNF     eVLBI project scientist
>Office: (+61) (0)2 93724608      Mobile: (+61) (0)439487601
>
>
>
>

-- 
----------------------------------------------------
Cormac Reynolds
Phone: +61 8 9266 3785
Fax: +61 8 9266 9246
email: c.reynolds_at_curtin.<!--nospam-->edu.au
----------------------------------------------------

Received on 2009-08-25 16:21:18