Re: mkfs options for a 16x hw raid5 and xfs (mostly large files)

[Justin Piszcz <jpiszcz@xxxxxxxxxxxxxxx>]

On Tue, 25 Sep 2007, Ralf Gross wrote:

> Ralf Gross schrieb:
> > > What do you get when (reading) from the raw device?
> > >
> > > dd if=/dev/sda bs=1M count=10240
> >
> > The server has 16 GB RAM, so I tried it with 20 GB of data.
> >
> > dd if=/dev/sdd of=/dev/null bs=1M count=20480
> > 20480+0 Datensätze ein
> > 20480+0 Datensätze aus
> > 21474836480 Bytes (21 GB) kopiert, 95,3738 Sekunden, 225 MB/s
> >
> > and a second try:
> >
> > dd if=/dev/sdd of=/dev/null bs=1M count=20480
> > 20480+0 Datensätze ein
> > 20480+0 Datensätze aus
> > 21474836480 Bytes (21 GB) kopiert, 123,78 Sekunden, 173 MB/s
> >
> > I'm taoo tired to interprete these numbers at the moment, I'll do some
> > more testing tomorrow.
>
> There is a second RAID device attached to the server (24x RAID5). The
> numbers I get from this device are a bit worse than the 16x RAID 5
> numbers (150MB/s read with dd).
>
> I'm really wondering how people can achieve transfer rates of
> 400MB/s and more. I know that I'm limited by the FC controller, but
> I don't even get >200MB/s.
>
> Ralf

Perhaps something is wrong with your setup?

Here are my 10 raptors in RAID5 using Software RAID (no hw raid 
controller):

p34:~# dd if=/dev/md3 of=/dev/null bs=1M count=16384
16384+0 records in
16384+0 records out
17179869184 bytes (17 GB) copied, 29.8193 seconds, 576 MB/s
p34:~#