From: Luke Lonergan <llonergan@greenplum.com>
To: Miguel <mmiranda@123.com.sv>
To: Postgresql Performance <pgsql-performance@postgresql.org>
Subject: Re: Best OS & Configuration for Dual Xeon w/4GB &
Date: Mon, 20 Mar 2006 13:27:56 -0800
Message-ID: <C0445E5C.1F938%llonergan@greenplum.com> (raw)
In-Reply-To: <441F1AC5.9050700@123.com.sv>
Miguel,
On 3/20/06 1:12 PM, "Miguel" <mmiranda@123.com.sv> wrote:
> i dont know, how can i check?
No matter - it's the benchmark that would tell you, it's probably "access
time" that's being measured even though the text says "seek time". The
difference is that seek time represents only the head motion, where access
time is the whole access including seek. Access times of 4.5ms are typical
of a single 10K RPM SCSI disk drive like the Seagate barracuda.
>> Transfer rates:
>> outside: 102400 kbytes in 2.075984 sec = 49326 kbytes/sec
>> middle: 102400 kbytes in 2.100510 sec = 48750 kbytes/sec
>> inside: 102400 kbytes in 2.042313 sec = 50139 kbytes/sec
>>
> I have 6 ultra a320 72G 10k discs
Yah - ouch. With 6 drives in a RAID10, you should expect 3 drives worth of
sequential scan performance, or anywhere from 100MB/s to 180MB/s. You're
getting from half to 1/3 of the performance you'd get with a decent raid
controller.
If you add a simple SCSI adapter like the common LSI U320 adapter to your
DL380G3 and then run software RAID, you will get more than 150MB/s with less
CPU consumption. I'd also expect you'd get down to about 2ms access times.
This might not be easy for you to do, and you might prefer hardware RAID
adapters, but I don't have a recommendation for you there. I'd stay away
from the HP line.
- Luke
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To: pgsql-performance@postgresql.org
Cc: llonergan@greenplum.com, mmiranda@123.com.sv
Subject: Re: Best OS & Configuration for Dual Xeon w/4GB &
In-Reply-To: <C0445E5C.1F938%llonergan@greenplum.com>
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