New Opteron box, dedicated to PostgreSQL

Hi,

while configuring my 1st PostgreSQL box with dual Opterons (2212) on  
FreeBSD, I have some questions:

1. Are there any precautions in fbsd to prevent from excessive page  
switching between the memory nodes?
    E.g. what happens if file cache pages (heavily used by Pg,  
planned 6GB) frequently not found on local node?
2. If there is no good solution for this problem, does it make sense  
to stay with one dualcore (soon quadcore) processor?
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?
4. Can I install the system on an Areca raid?

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