From: maurice <mhilarius@gmail.com>
To: NeilBrown <neilb@suse.de>
Cc: "Pavel Hofman" <pavel.hofman@ivitera.com>,
"Jérôme Poulin" <jeromepoulin@gmail.com>,
linux-raid <linux-raid@vger.kernel.org>
Subject: Re: Rotating RAID 1
Date: Mon, 15 Aug 2011 22:36:18 -0600 [thread overview]
Message-ID: <4E49F3C2.8090009@gmail.com> (raw)
In-Reply-To: <20110816084251.2d8e7831@notabene.brown>
On 8/15/2011 4:42 PM, NeilBrown wrote:
> ..I'm not sure from you description whether the following describes
> exactly
> what you are doing or not, but this is how I would do it.
> As you say, you need two bitmaps.
> So if there are 3 drives A, X, Y where A is permanent and X and Y are
> rotated off-site,
> then I create two RAID1s like this:
> mdadm -C /dev/md0 -l1 -n2 --bitmap=internal /dev/A /dev/X
> mdadm -C /dev/md1 -l1 -n2 --bitmap=internal /dev/md0 /dev/Y
>
> mkfs /dev/md1; mount /dev/md1 ...
>
> Then you can remove either or both of X and Y and which each is
> re-added it will
> recover just the blocks that it needs.
> X from the bitmap of md0, Y from the bitmap of md1.
>
> NeilBrown
How elegantly described.
After so many instances of being told "You should not use RAID as a
backup device like that!"
it is pleasant to hear you detail the "right way" to do this.
Thank you very much for that Neil.
--
Cheers,
Maurice Hilarius
eMail: /mhilarius@gmail.com/
prev parent reply other threads:[~2011-08-16 4:36 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-15 19:56 Rotating RAID 1 Jérôme Poulin
2011-08-15 20:19 ` Phil Turmel
2011-08-15 20:23 ` Jérôme Poulin
2011-08-15 20:21 ` Pavel Hofman
2011-08-15 20:25 ` Jérôme Poulin
2011-08-15 20:42 ` Pavel Hofman
2011-08-15 22:42 ` NeilBrown
2011-08-15 23:32 ` Jérôme Poulin
2011-08-15 23:55 ` NeilBrown
2011-08-16 6:34 ` Pavel Hofman
2011-09-09 22:28 ` Bill Davidsen
2011-09-11 19:21 ` Pavel Hofman
2011-09-12 14:20 ` Bill Davidsen
2011-08-23 3:45 ` Jérôme Poulin
2011-08-23 3:58 ` NeilBrown
2011-08-23 4:05 ` Jérôme Poulin
2011-08-24 2:28 ` Jérôme Poulin
2011-10-25 7:34 ` linbloke
2011-10-25 21:47 ` NeilBrown
2011-08-16 4:36 ` maurice [this message]
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