From mboxrd@z Thu Jan 1 00:00:00 1970 From: George Duffield Subject: Expand RAID5 array or switch to RAID10 Date: Wed, 17 Dec 2014 12:11:27 +0200 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: Sender: linux-raid-owner@vger.kernel.org To: "linux-raid@vger.kernel.org" List-Id: linux-raid.ids Hi I have a RAID5 array comprising four 3TB drives and I've basically got 100GB remaining free so it's time to expand the array. With this in mind, and considering my requirement is predominantly to increase capacity, I'm wondering whether it'd be best to add another 3TB drive and expand the array whilst retaining RAID5 or to switch out to a RAID10 array. My thinking is 1) adding a 5th 3TB drive to the existing array may result in drive failure during the rebuild; and 2) RAID10 is very expensive to implement. Hence, I'm tempted to consider other options (recognising that whilst it'd be convenient I don't actually need everything stored on a single array). One such option would be running two raid5 arrays comprised of 3x 3TB each yielding 12TB of storage across the two arrays. Questions: + Is my assumption re RAID5 drive failure correct/ likely? + Is there a non-destructive way to migrate from RAID5 to RAID10? + 2 x RAID5 arrays seems pretty appealing - from a reliability and cost effectiveness standpoint - yes/no?