Re: Fedora 8.0.1 XFS Tune on HW RAID for Max Write Throughput?

[Justin Piszcz <jpiszcz@xxxxxxxxxxxxxxx>]

On Mon, 17 Dec 2007, David Chinner wrote:

> On Sat, Dec 15, 2007 at 10:35:20PM -0600, Eric Sandeen wrote:
> > Alex Madarasz wrote:
> > > We're building a new Fedora 8.0.1 Linux system to stream data from a
> > > 250Msps ADC to disk, and want to start tuning the system configuration
> > > for maximum XFS write performance.  To date, without any significant
> > > effort at tuning our Fedora 7 dev system, we're seeing 250MBps write
> > > with 8-bit samples and ~ 300MBps write with 16-bit samples. We want to
> > > push the tuning as far as we can go with this architecture before we
> > > start looking at other hardware options.  Looking at various other
> > > tuning pages on the Web finds few that are interested in maxing out
> > > sequential writes to very large arrays while using SAS HW RAID with big
> > > fast SAS drives too.
> > ...
> >
> > > XFS Tuning Options?
> > >
> > > - HW RAID0:
> > >   - Array/logical disk HW RAID stripe size?
> > At any rate you'll want to match xfs's geometry with the raid geometry.
> >
> > >   - Cache enabled (some reports that cache s/b turned off?)?
> > If it's battery-backed cache, leave it on, and disable barriers in xfs
> > (it's a mount option)
> >
> > >   - xfs mkfs / mount options?
> > David mentioned these before as a generic place to start:
> >
> > # mkfs.xfs -f -l lazy-count=1,version=2,size=128m -i attr=2 -d agcount=4
> > <dev>
> > # mount -o logbsize=256k <dev> <mtpt>
> >
> > and that those would be upcoming new defaults for mkfs.
> >
> > 4 ags may not be what you want for a ~2T filesystem.
> Right - the 4 AG tuning is effectively for single disk configurations to
> limit parallelism and therefore keep seeks between AGs down. When you
> have multiple disks, the [new] mkfs defaults should be just fine (i.e.
> just drop the agcount suggestion).
>
> Cheers,
>
> Dave.
> --
> Dave Chinner
> Principal Engineer
> SGI Australian Software Group
Dave,

The mkfs.xfs defaults will be just fine for a HW raid device?

Justin.