| From: | Scott Ribe <scott_ribe(at)elevated-dev(dot)com> |
|---|---|
| To: | Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> |
| Cc: | pgsql-general General <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: 2 questions re RAID |
| Date: | 2011-06-17 17:35:11 |
| Message-ID: | 0885B7AA-C2AC-4B1C-AD6E-847F9C2ED4B2@elevated-dev.com |
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| Lists: | pgsql-general |
Thanks much for the specific info on Areca RAID cards. Very helpful.
On Jun 17, 2011, at 11:20 AM, Scott Marlowe wrote:
> The problem with RAID-5 is crappy write performance. Being big or
> small won't change that. Plus if the db is small why use RAID-5?
It's small enough that there's some other things going on at the same small server with 4 disk bays ;-) My thinking was that write-back cache might mitigate the poor write performance enough to not be noticed. This db doesn't generally get big batch updates anyway, it's mostly a constant stream of small updates coming in and I have a hard time imagining 256MB of cache filling up very often. (I have at least a fuzzy understanding of how WAL segments affect the write load.)
RAID-1 & RAID-10 are not ruled out, I'm just exploring options. And I'm not actually wanting to use RAID 5; it's RAID 6 that I'm considering...
--
Scott Ribe
scott_ribe(at)elevated-dev(dot)com
http://www.elevated-dev.com/
(303) 722-0567 voice
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