Message-ID: <0262F63EF2164C598FBA1CD8980BE206@rivendell>
From: "Reko Turja" <reko.turja@liukuma.net>
To: "Laszlo Nagy" <gandalf@shopzeus.com>,
	<pgsql-performance@postgresql.org>
Cc: "Tony Nagy" <tony@shopzeus.com>
References: <47ECB4F6.1040901@shopzeus.com>
Subject: Re: Planning a new server - help needed
Date: Fri, 28 Mar 2008 12:00:41 +0200
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> Question 1. We are going to use PostgreSQL 3.1 with FreeBSD. The pg 
> docs say that it is better to use FreeBSD because it can alter the 
> I/O priority of processes dynamically. The latest legacy release is 
> 6.3 which is probably more stable. However, folks say that 7.0 has 
> superior performance on the same hardware. Can I use 7.0 on a 
> production server?

FreeBSD 7.x is pretty stable, and it has the advantage of having the 
new ULE and other things that can't be MFC'd to 6.x branch. And as a 
long time FreeBSD enthusiast having Cisco sponsoring Dtrace, Nokia 
sponsoring scheduler development etc. 7.x is definitely in my opinion 
now the branch to install and start following for ease of upgrading 
later. Of course, as always check that your intended hardware is 
supported.

ULE which is pretty much the key for performance boost in 7.x branch 
isn't yet the default scheduler, but will be in 7.1 and afterwards. 
This means you have to roll custom kernel if you want to use ULE.

> Question 3. FreeBSD 7.0 can use the ZFS file system. I suspect that 
> UFS 2 + soft updates will be better, but I'm not sure. Which is 
> better?

For now I'd choose between UFS+gjournal or plain UFS, although with 
bigger disks journaling is a boon compared to fsck'ing plain UFS 
partition. ZFS isn't yet ready for production I think, but it seems to 
be getting there. This is opinion based on bug reports and discussions 
in stable and current mailing lists, not on personal testing though. 
My experiences with gjournal have been positive so far.

On the drives and controller - I'm not sure whether SCSI/SAS will give 
any noticeable boost over SATA, but based on personal experience SCSI 
is still ahead on terms of drive reliability. Whatever technology I'd 
choose, for production server getting decent battery backed controller 
would be the start. And of course a controller that does the RAID's in 
hardware.

-Reko