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Date: Thu, 19 Jul 2007 16:44:14 +0200
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To: Derek Ragona <derek@computinginnovations.com>
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Cc: freebsd-questions@freebsd.org, Gabriel Linder <linder@jeuxvideo.com>
Subject: Re: Swap size
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Derek Ragona wrote:
> At 03:03 AM 7/19/2007, Gabriel Linder wrote:
>> Hi,
>>
>> I plan to setup FreeBSD 6.2-RELEASE on my Core Duo laptop with 1GB of
>> RAM.
>>
>> The handbook says "ideal swap size is 2xRAM", so should I use 2GB of
>> swap ?
> 
> Yes unless you know how many applications will ever be run and their run
> size.  The 2xRAM is so you can always have a reasonable performance
> allowing swap.  You can still run out of swap, and this will cause a
> panic.  With disks so cheap, why not use 2XRAM?

Running out of swap doesn't cause a panic, it causes the largest process to be
killed.


>>  This seems a bit huge to me, I never used more than 400MB on Linux.
>> If so, is there a limit of swap partition size (or number) on i386
>> (for Linux it's 2GB per partition and 32 partitions max, but I don't
>> know for FreeBSD) ?

For a Desktop System 400M should be enough, I don't remember my Desktop system
to ever use more than 1m of swap. However, the swap size should be large enough
for a dump during a panic. So if you want to be able to do some debugging if
you ever run into panics, your swap should be at least as large as your memory.
Assuming that you might add more memory one day something between 2 or 4GB of
swap look reasonable to me.