Обсуждение: Re: Hardware/OS recommendations for large databases (
Dave,
Luke,
From: pgsql-performance-owner@postgresql.org [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of Dave Cramer
Sent: Tuesday, November 15, 2005 6:15 AM
To: Luke Lonergan
Cc: Adam Weisberg; pgsql-performance@postgresql.org
Subject: Re: [PERFORM] Hardware/OS recommendations for large databases (Have you tried the areca cards, they are slightly faster yet.
No, I've been curious since I read an earlier posting here. I've had a lot more experience with the 3Ware cards, mostly good, and they've been doing a lot of volume with Rackable/Yahoo which gives me some more confidence.
The new 3Ware 9550SX cards use a PowerPC for checksumming, so their write performance is now up to par with the best cards I believe. We find that you still need to set Linux readahead to at least 8MB (blockdev --setra) to get maximum read performance on them, is that your experience with the Arecas? We get about 260MB/s read on 8 drives in RAID5 without the readahead tuning and about 400MB/s with it.
- Luke
On Tue, Nov 15, 2005 at 09:33:25AM -0500, Luke Lonergan wrote: >write performance is now up to par with the best cards I believe. We >find that you still need to set Linux readahead to at least 8MB >(blockdev --setra) to get maximum read performance on them, is that your What on earth does that do to your seek performance? Mike Stone
Mike,
On 11/15/05 6:55 AM, "Michael Stone" <mstone+postgres@mathom.us> wrote:
We’re in decision support, as is our poster here, so seek isn’t the issue, it’s sustained sequential transfer rate that we need. At 8MB, I’d not expect too much damage though – the default is 1.5MB.
- Luke
On 11/15/05 6:55 AM, "Michael Stone" <mstone+postgres@mathom.us> wrote:
On Tue, Nov 15, 2005 at 09:33:25AM -0500, Luke Lonergan wrote:
>write performance is now up to par with the best cards I believe. We
>find that you still need to set Linux readahead to at least 8MB
>(blockdev --setra) to get maximum read performance on them, is that your
What on earth does that do to your seek performance?
We’re in decision support, as is our poster here, so seek isn’t the issue, it’s sustained sequential transfer rate that we need. At 8MB, I’d not expect too much damage though – the default is 1.5MB.
- Luke