Re: SATA drives performance

From: Ognjen Blagojevic <ognjen(at)etf(dot)bg(dot)ac(dot)yu>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: SATA drives performance
Date: 2009-12-24 21:09:41
Message-ID: 4B33D895.5020807@etf.bg.ac.yu
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Richard and others, thank you all for your answers.

My comments inline.

Richard Neill wrote:
> 2. Also, for reads, the more RAM you have, the better (for caching). I'd
> suspect that another 8GB of RAM is a better expenditure than a 2nd drive
> in many cases.

The size of the RAM is already four time of the database size, so I
believe I won't get any more benefit if it is increased. The number of
simultaneous connections to the database is small -- around 5.

What I'm trying to do with the hard disk configuration is to increase
the write speed.

> 3. RAID 0 is twice as unreliable as no raid. I'd recommend using RAID 1
> intead. If you use the Linux software mdraid, remote admin is easy.

No, actually it is HP ML series server with HW RAID. I don't have too
much experience with it, but I believe that the remote administration
might be hard. And that was the main reason I was avoiding RAID 1.

> 5. For a 2-disk setup, I think that main DB on one, with WAL on the
> other will beat having everything on a single RAID0.
>
> 6. The WAL is relatively small: you might consider a (cheap) solid-state
> disk for it.

These are exactly the thing I was also considering. -- but needed advice
from people who tried it already.

Regards,
Ognjen

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