Date: Fri, 22 Aug 2003 13:02:00 -0400 From: Tony Holmes <tony@crosswinds.net> To: freebsd-fs@FreeBSD.ORG Subject: Re: RAID 1+0 Message-ID: <20030822130200.B82013@crosswinds.net> In-Reply-To: <20030822164603.GB45178@cnd.mcgill.ca>; from mat@cnd.mcgill.ca on Fri, Aug 22, 2003 at 12:46:03PM -0400 References: <20030822101702.A73928@crosswinds.net> <20030822164603.GB45178@cnd.mcgill.ca>
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On +Aug 22, Mathew Kanner wrote:
>
> Hello Tony,
> I've just recently trashed a vinum raid10 volume by loosing
> two disks. So, yes it is possible in vinum, look for "RAID-10" in the
> manual.
That's what I would call RAID-0+1 (mirroring stripes).
Ie. plex A = 1 + 2 striped
plex B = 3 + 4 striped
volume = A + B mirrored
Dead Drive Chart - if these drives die, how is data?
Drive 1 2 3 4
1 OKAY OKAY DEAD DEAD
2 OKAY OKAY DEAD DEAD
3 DEAD OKAY OKAY OKAY
4 DEAD DEAD OKAY OKAY
ie. 50% of the cases you can recover (drive 1 and 1 dying is single drive)
What I'm looking for is RAID-1+0 (striping mirros)
Ie. plex A = 1 + 2 mirrored
plex B = 3 + 4 mirrored
volume = A + B striped
Drive 1 2 3 4
1 OKAY DEAD OKAY OKAY
2 DEAD OKAY OKAY OKAY
3 OKAY OKAY OKAY DEAD
4 OKAY OKAY DEAD OKAY
ie. 75% of the cases you can recover
For the RAID 1+0 case you require both drives of the same mirror
to die to lose your data.
Given vinums configuration file, we'd need something like the following
that is not supported (just to help you visualize).
drive d1 device /dev/da1e
drive d2 device /dev/da2e
drive d3 device /dev/da3e
drive d4 device /dev/da4e
volume raid10 setupstate
plex org striped 512k
subplex org concat
sd length 512m drive d1
subplex org concat
sd length 512m drive d2
plex org striped 512k
subplex org concat
sd length 512m drive d3
subplex org concat
sd length 512m drive d4
--
Tony Holmes
Founder and Senior Systems Architect
Crosswinds Internet Communications Inc.
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