Re: Swap size for a machine with 2GB of memory

From: Andrzej Krzysztofowicz (kufel!ankry@green.mif.pg.gda.pl)
Date: Sun Aug 19 2001 - 03:25:36 EST


>
> The Red Hat installation manual claims that the size of the swap partition
> should be twice the size of physical memory, but no more than 128MB.

This manual is outdated.

1. You hahe 2GB limit for a single swap file/partition now. And you can use
   many of them.
2. it sjould be <= 2* RAM, i.e. 0 <= SWAP <= 2*RAM. More is inefficient.
3. except kernels 2.4.x, where x <= 7-ac8, where you should have SWAP=0 or
   SWAP > RAM. 2.4.7-ac9 & 2.4.8 have already this problem fixed.

> The screaming hotrod machine Gary Sandine and I built around the Tyan S2464
> has 2GB of physical memory. Should I believe the above formula? If not,
> is there a more correct one for calculating needed swap on machines with
> very large memory?

Correct and universal formula for swap size is as always:
   SWAP = MAX_RAM_you_ever_need - physical_RAM_you_have

However in 2.4 more eficient (and in 2.40-7 obligatory) is:
   SWAP = MAX_RAM_you_ever_need > physical_RAM_you_have
          ? MAX_RAM_you_ever_need
;)

Andrzej
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