On Sat, Mar 18, 2000 at 02:58:52PM -0500, Trevor Astrope wrote:
: A document on the redhat.com site says raiding your swap partitions is a
: bad idea, because you will take a big performance hit if memory needed for
: the raid in case of failure resides in swap. The machine I am configuring
: is a dual 650 with 640mb of ram, but I thought the machine this is
: replacing (a p3-450 with 256mb ram was enough and it goes a few kb into
: swap). My question here is: if I just use 2 swap partitions that are not
: raided and the memory needed for the raid lives in swap on the primary
: drive that failed, are you not in the same position you were if you raided
: your swap in the first place?
Never, ever, not in a million years should you mkswap on an md partition.
The kernel's VM code "raid0's" the swap partitions internally, without the
extra md code.
Besides, I'm now going to play the part of the "big dumb guy" :) who asks
why on earth you're going to trust a critical system to software raid...
One can only assume we're talking about a critical system here, after all,
dual P-III/650's, 640MB RAM? That's definitely a big boy.
I've been using refurb'd AMI Megaraid 466's, that I've been getting with
16MB of cache onboard for $180 (warranted for a year), and U2-LVD drives.
The performance not only blows the doors off of software raid, it's more
reliable. Take for example, a site by a company we're incubating
They do MP3 streaming of independent music. A Megaraid 466, 16MB cache
and 6 IBM 36G U2W drives are on that puppy. It's a RAID 5 w/a hot
spare, so it's 144G. I've got reiserfs running on that raid, and wow,
is it ever FAST. I'm a whole lot more comfortable with hardware raid.
That machine can have two drives fail, and all I have to do is slam in
new drives, and sit back while the raid rebuilds, automagically. Hot-swap
drives also mean it can happen with the system up and running.
It's nice that the kernel supports "poor man's raid", which I've used on my
home PC before, but when you can find raid cards at a reasonable price that
have good support under Linux, why bother? I'd say *exactly* the same
thing if we were talking about NT's software raid, or anyone else's for
that matter..
--
Jason Costomiris <><
Technologist, cryptogeek, human.
jcostom {at} jasons {dot} org | http://www.jasons.org/
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