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Re: Performance advice

From: "Shridhar Daithankar" <shridhar_daithankar(at)persistent(dot)co(dot)in>
To: <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Performance advice
Date: 2003-06-24 08:19:54
Message-ID: 3EF85702.30194.3A69859@localhost (view raw or flat)
Thread:
Lists: pgsql-performance
On 24 Jun 2003 at 13:29, Shridhar Daithankar wrote:
> > - I have at my disposal one other server which has 2 Xeons, 10,000 RPM SCSI
> > drive.  Would it make sense to put Postgres on it and leave my apps running
> > on the more powerful 4 CPU server?

Argh.. Forgot it first time. 

With java runnning on same machine, I would not trust that machine for having 
free RAM all the time, no matter how much RAM you have put into it.

Secondly you are running linux which is known to have weird behaviour problems 
when it runs low on memory.

For both these reasons, I suggest you put your database on another machine. A 
dual CPU machine is more than enough. Put good deal RAM, around a GB and two 
SCSI disks, one for data and another for WAL. If you get RAID for data, great. 
But that should suffice otherwise as well.

> > 
> > - Would a RAID setup make the disk faster?  Because top rarely shows the
> > CPUs above 50%, I suspect maybe the disk is the bottleneck.
> 
> Yes it is. You need to move WAL to a different disk. Even if it is IDE. (OK 
> that was over exaggeration but you got the point). If your data directories and 
> WAL logs are on physically different disks, that should bump up performance 
> plenty.

In addition to that, on linux, it matters a lot as in what filesystem you use. 
IMO ext3 is strict no-no. Go for either reiserfs or XFS.

There is no agreement as in which file system is best on linux. so you need to 
experiment if you need every ounce of performance.

And for that you got to try freeBSD. That would gave you plenty of idea about 
performance differences. ( Especially I love man hier and man tuning on 
freeBSD. Nothing on linux comes anywhere near to that)

Bye
 Shridhar

--
"Who is General Failure and why is he reading my hard disk ?"Microsoft spel 
chekar vor sail, worgs grate !!(By leitner(at)inf(dot)fu-berlin(dot)de, Felix von Leitner)


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