Adaptect raid performance with FreeBSD

[Mark Sergeant]

I've got to say this seems pretty bad since my laptop gets ...

104857600 bytes transferred in 4.491311 secs (23346770 bytes/sec)


On Wed, 2004-01-14 at 22:53, Ari Suutari wrote:
> Hi,
> 
> I have been wondering if my disk setup should perform better than
> it is now doing. 
> 
> I have a dual PIII 500 Mhz with intel server mother board.
> (a couple of years old). On that, I have DPT (or currently Adaptec)
> raid controller "DPT PM2654U2", which supports 40 Mhz SCSI bus,
> giving a theoretical data transfer speed of 80 MB/s. There are
> two physical disks, which have been mirrored (ie. raid-1).
> The disks are maxtor atlas 10K4, I think that maxtor tells
> that they should give sustained transfer rate up to 72MB/s.
> I have confirmed that SCSI bus is at 80MB/s speed
> with dptutil.
> 
> The system is running FreeBSD 4.8.
> 
> However, when reading raw device with dd like this:
> 
> dd if=/dev/rda1s1a of=/dev/null bs=1m count=100
> 100+0 records in
> 100+0 records out
> 104857600 bytes transferred in 4.193832 secs (25002814 bytes/sec)
> 
> So, I get only about 25MB/s. Shouldn't I be getting something
> like 70 MB/s, or even more since there are two disks that
> can server read requests ?
> 
> Maybe there is something I could tune ? The BIOS doesn't
> have much, there is only setting to enable bus mastering (enabled)
> and another for pci latency timer values (was 40, I think)
> 
> 
> 	Ari S.
-- 
Mark Sergeant <msergeant at snsonline.net>
SNSOnline Technical Services
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