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

[Ralf Gross <Ralf-Lists@xxxxxxxxxxxx>]

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