Re: siis/atacam/ata/gmirror 8.0-BETA3 disk performance

From: Emil Mikulic <emikulic_at_gmail.com>
Date: Thu, 3 Sep 2009 00:11:38 +1000
On Wed, Sep 02, 2009 at 08:04:04AM -0400, Derek (freebsd lists) wrote:
> Hi,
> 
> I've been testing the new siis driver, and I have found no
> appreciable performance change, using dd as a measure of "raw"
> performance.
> 
> I get about 40MB/s read, and 30MB/s write.  See attached
> bench-*.txt files.

[...]

> ada0: <ST31500341AS CC1H> ATA/ATAPI-8 SATA 2.x device
> ada0: 1430799MB (2930277168 512 byte sectors: 16H 63S/T 16383C)

Huh, I have the same disk:

# dmesg | grep ad4
ad4: 1430799MB <Seagate ST31500341AS CC1H> at ata2-master SATA300

Sequential read on a disk this size should be around 120MB/sec at the
outer tracks:

# dd if=/dev/ad4 of=/dev/null bs=128k count=5000
655360000 bytes transferred in 5.171389 secs (126728039 bytes/sec)

> Also I find it surprising that my gmirror read is only 40MB/s,
> and not 60-80MB/s, any thoughts on this?

Stripe will give you higher throughput.
Mirror will give you more random seeks per second.

--Emil
Received on Wed Sep 02 2009 - 12:11:42 UTC

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