Re: XFS filessystem for Datawarehousing

Hi Steve,
I hope that performance between EXT3 and XFS is not only 5-8% . Such a small difference could be interpreted as
"noise", as you already mentioned.
I want to give many filesystem a try. Stability is also a concern, but I don't want to favour any FS over another .

Best Regards.
MIlen Kulev

-----Original Message-----
From: Steve Poe [mailto:steve(dot)poe(at)gmail(dot)com]
Sent: Wednesday, August 02, 2006 11:27 PM
To: Milen Kulev
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: [PERFORM] XFS filessystem for Datawarehousing

Milen,

For the past year, I have been running odbc-bench on a dual-opteron with 4GB of RAM using a 8GB sample data. I found
the performance difference between EXT3, JFS, and XFS is +/- 5-8%. This could be written-off as "noise" just for normal
server performance flux. If you plan on using the default kernel, ext3 will likely perform best (what I found). When I
added my own kernel, ext3 performed fair. What I've had to consider is what does each file system offer me as far as
data integrity goes.

You'll find greater ROI on performance by investing your time in other areas than chasing down a few percentage point
(like I have done). If you could borrow more RAM and/or more discs for your tests, Testing newer kernels and
read-ahead patches may benefit you as well.

Best of luck.

Steve Poe

On 8/2/06, Milen Kulev <makulev(at)gmx(dot)net> wrote:

Hi Like, Mark , Alvaro and Andrew,

Thank you very much for sharing you experience with me.
I want to compare DHW performance of PG/Bizgres on different filesystems and difffrent
Block sizes.

The hardware will be free for me in a week or too (at a moment another project is running on it) and then I will test
diffrenet setups and will post the results.

I MUST (sorry, no other choice) use SLES6 R3, 64 bit. I am not sure at all that I will get enough budget to get
approapriate RAID controller, and that is why I intent to use software RAID.

I am pretty exited whether XFS will clearly outpertform ETX3 (no default setups for both are planned !). I am not sure
whether is it worth to include JFS in comparison too ...

Best Regards,
Milen Kulev

-----Original Message-----
From: Luke Lonergan [mailto: llonergan(at)greenplum(dot)com <mailto:llonergan(at)greenplum(dot)com> ]
Sent: Wednesday, August 02, 2006 4:43 AM
To: Milen Kulev; pgsql-performance(at)postgresql(dot)org
Subject: Re: [PERFORM] XFS filessystem for Datawarehousing

Milen,

On 8/1/06 2:49 PM, "Milen Kulev" <makulev(at)gmx(dot)net> wrote:

> Is anyone using XFS for storing/retrieving relatively large amount of
> data (~ 200GB)?

I concur with the previous poster's experiences with one additional
observation:

We have had instabilities with XFS with software RAID (md) on 32-bit Xeons running RedHat4 U3 with the Centos 4.3
unsupported SMP kernel. XFS would occasionally kernel panic under load.

We have had no problems with XFS running on the same OS/kernel on 64-bit under heavy workloads for weeks of continuous
usage. Each server (of 16
total) had four XFS filesystems, each with 250GB of table data (no indexes) on them, total of 16 Terabytes. We tested
with the TPC-H schema and queries.

We use the default settings for XFS.

Also - be aware that LVM has a serious performance bottleneck at about 600MB/s - if you are working below that
threshold, you may not notice the issue, maybe some increase in CPU consumption as you approach it.

- Luke

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