Re: Dell Perc/6

[Tore Halset <halset(at)pvv(dot)ntnu(dot)no>]

On Feb 13, 2008, at 12:06, Dave Cramer wrote:

> On 13-Feb-08, at 5:02 AM, Tore Halset wrote:
>
> > Hello.
> >
> > I think I started that discussion. We ended up buying a Dell 2900  
> > with PERC 6/i and 10 * 145GB SAS 3,5" 15KRpm discs. 6 of the SAS  
> > discs are in a raid 10 for the database, 2 in a mirror for the wal  
> > and the last 2 in a mirror for the OS. We get 350MB/s writing and  
> > 380MB/s reading to/from the raid 10 area using dd. The OS is Ubuntu  
> > and the filesystem for the raid 10 is ext3.
> Wow that's fantastic. Just to be sure, did you make sure that you  
> read and wrote 2x memory to take the cache out of the measurement ?
>
> Dave


The box have 16GB of ram, but my original test file was only 25GB.  
Sorry. Going to 33GB lowered the numbers for writing. Here you have  
some samples.

% sh -c "dd if=/dev/zero of=bigfile bs=8k count=4000000 && sync"
32768000000 bytes (33 GB) copied, 103.722 seconds, 316 MB/s
32768000000 bytes (33 GB) copied, 99.669 seconds, 329 MB/s

% time dd if=bigfile of=/dev/null bs=8k
32768000000 bytes (33 GB) copied, 85.4235 seconds, 384 MB/s
32768000000 bytes (33 GB) copied, 85.4628 seconds, 383 MB/s

Regards,
 - Tore.