Linux RAID subsystem development
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From: Mike Accetta <maccetta@laurelnetworks.com>
To: Justin Piszcz <jpiszcz@lucidpixels.com>
Cc: Maurice Hilarius <maurice@harddata.com>, linux-raid@vger.kernel.org
Subject: Re: deliberately degrading RAID1 to a single disk, then back again
Date: Wed, 27 Jun 2007 18:23:59 -0400	[thread overview]
Message-ID: <4682E37F.9080303@laurelnetworks.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0706261421430.3561@p34.internal.lan>

Justin Piszcz wrote:
> mdadm /dev/md0 --fail /dev/sda1
> 
> On Tue, 26 Jun 2007, Maurice Hilarius wrote:
> 
...
>>> From time to time I want to "degrade" back to only single disk, and turn
>> off RAID as the overhead has some cost
>>> From time to time I want to restore to RAID1 function, and re-synch the
>> pair to current.
>>
>> Yes, this is a backup scenario..
>>
>> Are there any Recommendations ( with mdadm syntax)  please?

Plus

   mdadm /dev/md0 --remove /dev/sda1

to take the drive out of the array and

   mdadm /dev/md0 --add /dev/sda1

to put it back and start the re-sync.

When you mention "turn off RAID" do you mean to not even bring up the disk
as a degraded array?  If all you do is fail and remove the partition, RAID is
actually still running to manage the single remaining partition, but I would
expect that overhead to be minimal.
-- 
Mike Accetta

ECI Telecom Ltd.
Transport Networking Division, US (previously Laurel Networks)

      reply	other threads:[~2007-06-27 22:23 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-06-26 18:01 deliberately degrading RAID1 to a single disk, then back again Maurice Hilarius
2007-06-26 18:22 ` Justin Piszcz
2007-06-27 22:23   ` Mike Accetta [this message]

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