New Opteron box, dedicated to PostgreSQL

[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.

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.