File systems (RE: Sanity check requested)

From: "Nick Fankhauser" <nickf(at)ontko(dot)com>
To: "Pgsql-Performance(at)Postgresql(dot) Org" <pgsql-performance(at)postgresql(dot)org>
Subject: File systems (RE: Sanity check requested)
Date: 2003-07-18 14:31:46
Message-ID: NEBBLAAHGLEEPCGOBHDGKEHHHMAA.nickf@ontko.com
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Thanks for the suggestions in the FS types- especially the Debian oriented
info. I'll start by playing with the memory allocation parameters that I
originally listed (seems like they should provide results in a way that is
unaffected by the disk IO). Then once I have them at optimal values, move on
to trying different file systems.

I assume that as I make changes that affect the disk IO performance, I'll
then need to do some testing to find new values for the IO cost for the
planner- Do you folks have some ballpark numbers to start with for this
based on your experience? I'm departing in three ways from the simple IDE
model that (I presume) the default random page cost of 4 is based on- The
disks are SCSI & RAID and the FS would be different.

At this point, I can't think of any better way to test this than simply
running my local test suite with various values and recording the wall-clock
results. Is there a different approach that might make more sense? (This
means that my results will be skewed to my environment, but I'll post them
anyway.)

I'll post results back to the list as I get to it- It might be a slow
process Since I spend about 18 hours of each day keeping the business
running, I'll have to cut back on sleep & do this in the other 10 hours. <g>

-NF

> Shridhar Daithankar wrote:
> I appreciate your approach but it almost proven that ext2 is
> not the best and fastest out there.
>
> Agreed.

> Ang Chin Han wrote:
> We've been using ext3fs for our production systems. (Red Hat Advanced
> Server 2.1)
>
> And since your (Nick) system is based on Debian, I have done some rough
> testing on Debian sarge (testing) (with custom 2.4.20) with ext3fs,
> reiserfs and jfs. Can't get XFS going easily on Debian, though.
>
> I used a single partition mkfs'd with ext3fs, reiserfs and jfs one after
> the other on an IDE disk. Ran pgbench and osdb-x0.15-0 on it.
>
> jfs's has been underperforming for me. Somehow the CPU usage is higher
> than the other two. As for ext3fs and reiserfs, I can't detect any
> significant difference. So if you're in a hurry, it'll be easier to
> convert your ext2 to ext3 (using tune2fs) and use that. Otherwise, it'd
> be nice if you could do your own testing, and post it to the list.
>
> --
> Linux homer 2.4.18-14 #1 Wed Sep 4 13:35:50 EDT 2002 i686 i686 i386
> GNU/Linux
> 2:30pm up 204 days, 5:35, 5 users, load average: 5.50, 5.18, 5.13
>

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