Re: New Opteron box, dedicated to PostgreSQL

Am 16.03.2007 um 21:04 schrieb Vivek Khera:

>
> On Mar 16, 2007, at 7:17 AM, Claus Guttesen wrote:
>
>>> while configuring my 1st PostgreSQL box with dual Opterons (2212) on
>>> FreeBSD, I have some questions:
>>>
>>> 3. What are the recommendations for tuning I/O)?
>>>     - setting sysctl vfs.read_max to 16 or 32
>>>     - rebuilding the relevant filesystem with 32K blocks and 4K  
>>> frags
>>>     Are these reliable?
>>
>> The following were suggetions from Vivek Khera:
>
> I've recently bumped the shmall and shmmax on my dual opteron with  
> 16GB of RAM, and increased correspondingly the shared buffers.
>
> The max shmall you can set on freebsd (at least 6.1) is 2147483647,  
> so I set shmall to 524288 to correspond.  This supports 250000  
> shared buffers and 100 max connections.  Might support more, but  
> definitely not 260000.
This box will start with 8GB of RAM, should also support 100  
connections, so I will try half of your values (pretty your settings  
posted by Claus Guttesen <[email protected]>).
>
> I'm also using vfs.read_max=32 but I haven't really tested if it  
> makes a big difference in formal benchmarks.
>
> The other day I was having some I/O overload, so I tried setting  
> vfs.hirunningspace to 3K but it didn't solve my immediate problem.   
> I've left that setting for now.  Doesn't seem to really make a big  
> difference.
>
> I find that the adaptec 2230SLP RAID controllers are not able to  
> keep up with my load, but the LSI 320-2X is.  I'm currently  
> investigating external arrays attached via fibre for some boost.
This box will have an Areca ARC-1261ML (RAID 1 for OS and WAL, RAID 0  
with 7xRAID1 for pg_data).
Any hints beside the usual partition alignment and stripe size of  
128kB ?
Do you use ufs2 with softupdates?

regards, Axel
---------------------------------------------------------------------
Axel Rau, ☀Frankfurt , Germany                       +49 69 9514 18 0


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