On Wed, 2 Jul 2008, Justin Vassallo wrote:
>
> **Current hardware setup:
> SunFire X4200 M2 with 16GB memory, 4 internal 70G 15krpm 2.5" SAS drives,
> with a raidz1 across the 4 discs. Db feels a little slow and getting slower
> quickly.

Raidz1 was a bad choice here for performance but it fit.

> C) 2*2540 w 12*300GB 3.5" 15krpm 3 Gb/sec SAS disks, dual controllers,
> 2*512M cache; dual dual-port PCIe cards (no spare). Max 515W/array=1030W

I have a 2540 here with 12*300GB drives and like it a lot.  It was 
easy to setup. Two 2540's would be a dream since then you can split 
the mirrors across the two arrays for maximal reliability and 
performance.  You could even use quad-mirroring without too much hit 
by also splitting across multipath channels.  However, the 2540 is 
pretty expensive.

> **Consideration factors:
> 1) 2.5" disks produce less vibration and are less sensitive to it, so seek
> time is better and more reliable. Also, less heat so less energy consumed.
> Any other array i should consider?

While it is not a dedicated "array" and I have no personal experience 
with it, I think you should definitely look at the Sun Fire X4240 
Server since it provides up 16 of those wonderful tiny 2.5" disks and 
the whole thing fits in 2U space like your existing server.  The entry 
cost is half the price of one 2540 so you can use the money you save 
to stuff it with RAM.  On a "try and buy" program you can test it out 
with your workload and reject it if it is not satisfactory.  The only 
problem is if the whole server craters and can't be immediately 
repaired but this is a problem regardless.  Just pay for a better 
service contract and buy a spare server if need be.

One thing you lose with this server approach is that it does not 
provide a NVRAM cache like the dedicated arrays do, and that may 
impact database update performance a bit.

> 3) which setup will perform better? I've seen posts saying the 2540 is half
> the 6140 (zfs-discuss: some trends from the test center of SUN/LSI: 2540 /
> ca. 100 KIOPs, ca. 600 MB/s; 6140 / ca. 200 KIOPs, ca. 1000 MB/s)

I don't know anything about the 6140, but the disks in the 2540 
operate in a sort of active/standby scheme where half of the drives 
are active on each controller.  Each controller also mirrors the 
uncommitted data in its NVRAM by default (which costs in write 
performance) so that it can take over the writes if the other 
controller fails.

Bob
======================================
Bob Friesenhahn
[EMAIL PROTECTED], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

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