swap - 2 HDs
lars+lister.freebsd at adventuras.no
Fri Dec 16 06:37:41 PST 2005
> Will Maier wrote:
>>On Fri, Dec 16, 2005 at 09:33:57AM -0300, Aguiar Magalhaes wrote:
>>>Is It recommended to configure swap area in both HDs ??
>>I don't see the point -- swap is where pages that don't fit in your
>>real memory go. It's less optimal than real memory in terms of
>>latency, but I don't see how two disks would make swap performance
> This is contrary to the "usual" advice which is to split swap across
> disks AFAIK. I've never done any benchmarks, but my gut feeling would
> be that if the disks were on separate controllers, and if the machine
> did swap regularly then two swap partitions would be beneficial. Even
> on the same controller it could easily make a difference since
> individual IDE/SATA disks can't actually reach the performance of the
> channel as a whole.
>From observation one can see that freebsd use the swap-partitions equally.
You probarly do want to make swap-partitions on all disks, but you may
later want to swapoff what is on the most busy disk if the disks are
> Given that these are large hard disks, what's 2 or 4Gb in the grand
> scheme? A drop in the ocean, so I would (and do) put swap on both.
> Of course, if the machine actually swaps regularly then investing in
> more RAM would give the best performance!
> PS If the two disks are larger than your actual needs, then you might
> want to consider emergency scenarios like one of your disks dieing. If,
> for example, you put a spare, bootable version of FreeBSD on the 2nd
> disk to aid recovery then that OS will need a swap partition anyway and
> you might as well use it regularly. $0.02
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