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Re: Looking for a cheap upgrade (RAID)

From: Shridhar Daithankar <shridhar_daithankar(at)persistent(dot)co(dot)in>
To: pgsql-performance <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Looking for a cheap upgrade (RAID)
Date: 2003-05-03 08:02:49
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Lists: pgsql-performance
On Saturday 03 May 2003 02:50, scott.marlowe wrote:
> Seeing as you'll have 2 gigs of RAM, your swap partition is likely to grow
> cob webs, so where you put it probably isn't that critical.
> What I usually do is say take 4 120 Gig drives, allocate 1 gig on each for
> swap, so you have 4 gigs swap (your swap should be larger than available
> memory in Linux for performance reasons) and the rest of the drives split
> so that say, the first 5 or so gigs of each is used to house most of the
> OS, and the rest for another RAID array hosting the database.  Since the
> root partition can't be on RAID5, you'd have to set up either a single
> drive or a mirror set to handle that.

Setting swap in linux is a tricky proposition. If there is no swap at all, 
linux has behaved crazily in past. These days situation is much better.

In my experience with single IDE disk, if swap usage goes above 20-30MB due to 
shortage of memory, machine is dead in waters. Linux sometimes does memory 
inversion where swap used is half the free memory but swap is not freed but 
that does not hurt really..

So my advice is, setting swap more tahn 128MB is waste of disk space. OK 256 
in ultra-extreme situations.. but more than that would a be unadvisable 


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Subject: Re: Looking for a cheap upgrade (RAID)
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