Date: Mon, 3 Sep 2001 14:20:56 -0400 (EDT) From: Chris BeHanna <behanna@zbzoom.net> Cc: FreeBSD-Stable <stable@FreeBSD.ORG> Subject: Re: RAID5 Message-ID: <20010903141721.D10812-100000@topperwein.dyndns.org> In-Reply-To: <030201c1349b$a0c254b0$2aa8a8c0@melim.com.br>
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On Mon, 3 Sep 2001, Ronan Lucio wrote:
> Hi All,
>
> I have a doubt about RAID5:
>
> If I have 3 HDs with 36 Gb each in RAID5, what is
> my total abaliable space?
72GB.
> Can I select it?
> For example: Can I create 20 Gb for parity + 88 Gb of
> avaliable space?
No. RAID-5 stripes parity information across all three drives:
data data parity
data parity data
parity data data
etc.
You can bump up the available space by adding more spindles (only
one stripe of a stripeset is parity), but the tradeoff is that the
parity calculations may degrade write performance when you do that.
FWIW, I set up a 4-drive RAID-5 volume with an associated
journaling device on Solaris 8 that performs pretty well for home
directories. I wouldn't expect vinum to be any different in that
regard, given sufficient CPU (my Solaris volume is served from a
two-CPU E450, just as a reference point).
--
Chris BeHanna
Software Engineer (Remove "bogus" before responding.)
behanna@bogus.zbzoom.net
I was raised by a pack of wild corn dogs.
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