From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Accetta Subject: Re: deliberately degrading RAID1 to a single disk, then back again Date: Wed, 27 Jun 2007 18:23:59 -0400 Message-ID: <4682E37F.9080303@laurelnetworks.com> References: <4681546B.4030709@harddata.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Justin Piszcz Cc: Maurice Hilarius , linux-raid@vger.kernel.org List-Id: linux-raid.ids 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)