From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Brown Subject: Re: Resync intermittently writes to spare drives, waking them up Date: Thu, 14 Apr 2011 10:32:53 +0200 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 13/04/2011 23:10, Rory Jaffe wrote: > I have a RAID5 array with 4 active devices and two spares. The spares > are normally in sleep mode. I ran a resync with: > > echo repair> /sys/devices/virtual/block/md0/md/sync_action > > About 20 times (evenly spaced apart) during the resync, the spares > were written to, waking them up. Is that behavior desired? It seems to > me that it's a waste--I don't know why the resync would bother with > the spares. > This isn't an answer to your question, but I would recommend changing to a raid 6 with 5 devices and one spare. Raid 6 gives you /much/ better reliability - you can thing of it as Raid 5 + hot spare with the hot spare already synchronised.