RE: [linux-lvm] LVM System

[Austin Gonyou <austin@coremetrics.com>]

On Mon, 2002-03-04 at 17:39, Steve Wray wrote:
> I'd recommend ext3 with data journalling for sensitive
> filesystems. Its slower than XFS but (seems to) scale better with
> striping and large files. XFS performance (seems to) fall off
> very rapidly as file size exceeds buffer size.
> 
> XFS only journals metadata. So on event of a crash,
> the filesystem structure will (likely) be sound, but theres
> no guarantee that the data blocks will be uncorrupted!!!
> 
> XFS is very nice tho, in that volumes and filesystems can
> be grown with no downtime at all (without even unmounting).
> 
> You might want to do some benchmarking before committing
> to a build (thats recently saved my butt actually).
> 

I've only got a couple of things to say in the regard about XFS and
performance Falling off. 

XFS's performance doesn't fall off in the respects you've spoken about.
It's a misconception when using LVM, or evms, etc along with XFS. 

I ran into a similar issue, and was convinced it was XFS or LVM, etc. 
This is in the relation of using XFS and LVM, vs. XFS with no LVM, and
then testing increasing filesizes with iozone. 

What I found was that dbench, and iozone both did not perform very well
with respect to software raid or striping, but that in fact the
filesystems themselves performed about 100% faster than without LVM
striping or LVM Concat. 

So much faster that my database guys noticed the enourmous increase in
speed on a test setup I created for them. One was using LVM, one was
not, with XFS. The one which was NOT using LVM had a hardware stripe
setup with write-back caching and adaptive read-ahead. The controller
has 128MB pc100Dimm. Using a 3 drive RAID 0 hardware, vs 3 drives
striped with LVM was an enourmous downgrade when benchmarking..but
actual use, db inserts, file create, etc, ran >100% faster than with
Hardware striping. 

I did the same test with Reiser and Ext2/3, none fared as well, but they
all did better with LVM and striping than without.



> 
> > -----Original Message-----
> > From: linux-lvm-admin@sistina.com
> [mailto:linux-lvm-admin@sistina.com]On
> > Behalf Of Anthony W. Marino
> > Sent: Tuesday, 5 March 2002 10:39 a.m.
> > To: linux-lvm@sistina.com
> > Subject: [linux-lvm] LVM System
> >
> >
> > Any thoughts or articles that would be usefull in determining the
> quality
> > on the following combination would be greatly appreciated:
> >
> > LVM 1.x
> > 3Ware 7800 Raid Controller
> > Maxtor 40GB harddrives
> > XFS Journalling FS
> > SuSE 2.4.18+ Linux
> >
> >
> > Thank You,
> > Anthony
> >
> > _______________________________________________
> > linux-lvm mailing list
> > linux-lvm@sistina.com
> > http://lists.sistina.com/mailman/listinfo/linux-lvm
> > read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html
> >
> 
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html
-- 
Austin Gonyou
Systems Architect, CCNA
Coremetrics, Inc.
Phone: 512-698-7250
email: austin@coremetrics.com

"It is the part of a good shepherd to shear his flock, not to skin it."
Latin Proverb