Date: Fri, 16 Dec 2005 13:38:38 +0000 From: Alex Zbyslaw <xfb52@dial.pipex.com> To: freebsd-questions@freebsd.org Subject: Re: swap - 2 HDs Message-ID: <43A2C35E.9060206@dial.pipex.com> In-Reply-To: <20051216131451.GV2413@merkur.atekomi.net> References: <20051216123357.4932.qmail@web31611.mail.mud.yahoo.com> <20051216131451.GV2413@merkur.atekomi.net>
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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 >much better. > > 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. 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! --Alex 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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