Message-ID: <47ECCCBF.40908@shopzeus.com>
Date: Fri, 28 Mar 2008 11:47:27 +0100
From: Laszlo Nagy <gandalf@shopzeus.com>
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To: Claus Guttesen <kometen@gmail.com>, pgsql-performance@postgresql.org
Subject: Re: Planning a new server - help needed
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> I guess you mean postgresql 8.3.1? :-)
>   
Yep. Sorry.
>>  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?
>>     
>
> I'd stick with ufs2 atm. There are some issues with zfs which probably
> have been ironed out by now but ufs2 has been deployed for a longer
> time. Performance-wise they are about the same.
>   
Thank you. I suspected the same but it was good to get positive 
confirmation.
>>  Question 4. How to make the partitions? This is the hardest question.
>>  Here is my plan:
>>
>>  - the OS resides on 2 disks, RAID 1
>>  - the databases should go on 8 disks, RAID 0 + 1
>>     
>
> If you have enough disks raid-6 should perform almost as good as raid
> 1+0. 
Hmm, I have heard that RAID 1 or RAID 1 + 0 should be used for 
databases,  never RAID 5. I know nothing about RAID 6. I guess I must 
accept your suggestion since you have more experience than I have. :-) 
Obviously, it would be easier to manage a single RAID 6 array.
> I've setup 11 disks in raid-6 plus one hotspare so I can get more
> space out of it. "Enough disks" are approx. eight and up.
>   
The RAID controller that I have selected can only handle 8 disks. I 
guess I need to find a different one with 16 channels and use more 
disks. So are you saying that with all disks in a bigger RAID 6 array, I 
will get the most out of the hardware? In that case, I'll try to get a 
bit more money from the management and build RAID 6 with 12 disks.

I also feel that I need to use a separate RAID 1 array (I prefer 
gmirror) for the base system.

Thanks,

   Laszlo