On Aug 8, 2006, at 5:28 PM, Joshua D. Drake wrote:
> Thomas F. O'Connell wrote:
>> On Aug 8, 2006, at 4:49 PM, Joshua D. Drake wrote:
>>>> I am considering a setup such as this:
>>>> - At least dual cpu (possibly with 2 cores each)
>>>> - 4GB of RAM
>>>> - 2 disk RAID 1 array for root disk
>>>> - 4 disk RAID 1+0 array for PGDATA
>>>> - 2 disk RAID 1 array for pg_xlog
>>>> Does anyone know a vendor that might be able provide such setup?
>> Wouldn't it be preferable to put WAL on a multi-disk RAID 10 if
>> you had the opportunity? This gives you the redundancy of RAID 1
>> but approaches the performance of RAID 0, especially as you add
>> disks to the array. In benchmarking, I've seen consistent success
>> with this approach.
>
> WALL is written in order so RAID 1 is usually fine. We also don't
> need journaling for WAL so the speed is even faster.
In which case, which is theoretically better (since I don't have a
convenient test bed at the moment) for WAL in a write-heavy
environment? More disks in a RAID 10 (which should theoretically
improve write throughput in general, to a point) or a 2-disk RAID 1?
Does it become a price/performance question, or is there virtually no
benefit to throwing more disks at RAID 10 for WAL if you turn off
journaling on the filesystem?
--
Thomas F. O'Connell
Sitening, LLC
http://www.sitening.com/
3004B Poston Avenue
Nashville, TN 37203-1314
615-469-5150 x802
615-469-5151 (fax)