Date: Thu, 12 Jul 2001 00:09:11 +0100 From: James Greenhalgh <james-list@ntlworld.com> To: "Richard E. Hawkins" <dochawk@psu.edu> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: swap with raid array? Message-ID: <20010712000911.252df892.james-list@ntlworld.com> In-Reply-To: <200107111816.f6BIGUw00969@fac13.ds.psu.edu> References: <200107111816.f6BIGUw00969@fac13.ds.psu.edu>
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On Wed, 11 Jul 2001 14:16:30 -0400 "Richard E. Hawkins" <dochawk@psu.edu> wrote: > We're about to set up a server with 2G of ram and a 5 disk striped RAID > array with a hot standby. I've started wondering about the swap, > though: if the array appears as a single disk to the os, wouldn't the > swap partition be striped as well? does this make sense? Also, will > this survive failover? Yes, it would be striped too if on a slice of the main logical disk. Probably better to create two logical disks, one dedicated for the swap - so you can select a better caching strategy for it or raid level. If you want to avoid striped swap you could create a small logical drive for each physical disk and give them all the same swap priority to load balance them, but all you'll end up doing is getting in the way of the RAID cards own load balancing and taking away its ability to survive a disk failure. Personally my swap (same physical disk configuration as yours) lives on a raid level 5 logical drive spread across all disks, since in theory that's the most robust way. I haven't yet pulled one of the drives to test this theory. > Theres's also the question of whether or not swap even makes sense with > 2G of ram--won't it already be done for if it hits that??? Well that's another question entirely isn't it? ;-) Swap is always useful I find - since a dormant process chewing up a lot of your ram should get swapped out, sidestepping the problem for a while.. Someone's bound to disagree with me of course, but it's my personal strategy ;-) -- find great crazy-mad out-of-head experience from japan. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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