Re: RAID card recommendation

On 12/1/09 6:08 PM, "Karl Denninger" <karl(at)denninger(dot)net> wrote:

> Scott Carey wrote:
>>
>> On 11/24/09 11:13 AM, "Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com>
>> <mailto:scott(dot)marlowe(at)gmail(dot)com> wrote:
>>
>>
>>
>>
>>>
>>> They get good reviews as well. Both manufacturers have their "star"
>>> performers, and their "utility" or work group class controllers. For
>>> what you're doing the areca 12xx or 3ware 95xx series should do fine.
>>>
>>>
>>
>>
>> -1 to 3ware's SATA solutions
>>
>> 3ware 95xx and 96xx had performance somewhere between PERC 5 (horrid) and
>> PERC 6 (mediocre) when I tested them with large SATA drives with RAID 10.
>> Haven't tried raid 6 or 5. Haven't tried the "SA" model that supports SAS.
>> When a competing card (Areca or Adaptec) gets 3x the sequential throughput
>> on an 8 disk RAID 10 and only catches up to be 60% the speed after heavy
>> tuning of readahead value, there's something wrong.
>> Random access throughput doesn't suffer like that however -- but its nice
>> when the I/O can sequential scan faser than postgres can read the tuples.
>>
> What operating system?
>
> I am running under FreeBSD with 96xx series and am getting EXCELLENT
> performance. Under Postgres 8.4.x on identical hardware except for the disk
> controller, I am pulling a literal 3x the iops on the same disks that I do
> with the Adaptec (!)
>
> I DID note that under Linux the same hardware was a slug.
>
> Hmmmmm...
>

Linux, Centos 5.3. Drivers/OS can certainly make a big difference.

>
> -- Karl
>