Message-ID: <4BB64B24.2030001@tweakers.net>
Date: Fri, 02 Apr 2010 21:53:08 +0200
From: Arjen van der Meijden <acmmailing@tweakers.net>
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To: pgsql-performance@postgresql.org
Subject: Re: Using high speed swap to improve performance?
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What about FreeBSD with ZFS? I have no idea which features they support 
and which not, but it at least is a bit more free than Solaris and still 
offers that very nice file system.

Best regards,

Arjen

On 2-4-2010 21:15 Christiaan Willemsen wrote:
> Hi there,
>
> About a year ago we setup a machine with sixteen 15k disk spindles on
> Solaris using ZFS. Now that Oracle has taken Sun, and is closing up
> Solaris, we want to move away (we are more familiar with Linux anyway).
>
> So the plan is to move to Linux and put the data on a SAN using iSCSI
> (two or four network interfaces). This however leaves us with with 16
> very nice disks dooing nothing. Sound like a wast of time. If we were to
> use Solaris, ZFS would have a solution: use it as L2ARC. But there is no
> Linux filesystem with those features (ZFS on fuse it not really an option).
>
> So I was thinking: Why not make a big fat array using 14 disks (raid 1,
> 10 or 5), and make this a big and fast swap disk. Latency will be lower
> than the SAN can provide, and throughput will also be better, and it
> will relief the SAN from a lot of read iops.
>
> So I could create a 1TB swap disk, and put it onto the OS next to the
> 64GB of memory. Then I can set Postgres to use more than the RAM size so
> it will start swapping. It would appear to postgres that the complete
> database will fit into memory. The question is: will this do any good?
> And if so: what will happen?
>
> Kind regards,
>
> Christiaan
>