good performing SCSI RAID5 ( was: asr ( 2015S ) support in 5.4 amd64? )

[Scott Long]

Steven Hartland wrote:

> ----- Original Message ----- From: "Dan Nelson" <dnelson at allantgroup.com>
> 
>> The faster rpms will get you more concurrent I/Os per second but won't
>> do as much for throughput.  My asr 3200S cards got repurposed before I
>> could try them with 5.x, but with the 370F firmware I'm pretty sure I
>> was able to get more than 40MB/sec reads out of them on 4.x with 4-disk
>> RAID5 sets.  Since the asr driver needs Giant, try a UP kernel and see
>> if it goes any faster.
> 
> 
> Stated max seq read on the drives ( Maxtor 10k IV's ) is 89MB/s
> where as the Seagate SATA's its 65MB/s so its a noticeable difference.
> For the RAID to only give 27->33MB/s ( still testing stripe sizes ) is
> disappointing to say the least, especially considering I have the SATA
> RAID giving me 200MB/s.
> 
>    Steve
> 

The ASR 370F firmware brought performance from 'abysmal' to 'slightly 
tolerable'.  Under ideal conditions, it has been benchmarked to get
close to 170MB/s, but you need to be very careful about stripe alignment
and cache settings.  Oh, and that was RAID-0, not RAID-5.

Scott