From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: Raid5 to another raid level?? Date: Fri, 2 Sep 2011 22:49:38 +1000 Message-ID: <20110902224938.74c30811@notabene.brown> References: <-7094796685559591664@unknownmsgid> <20110902121959.173a1aa9@notabene.brown> <20110902202235.0194d779@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Michael Busby Cc: john.robinson@anonymous.org.uk, linux-raid@vger.kernel.org List-Id: linux-raid.ids On Fri, 2 Sep 2011 11:35:30 +0100 Michael Busby wrote: > Great, will test that in a bit >=20 > will mdadm 3.2.2 support converting raid4 to raid5 >=20 > "A RAID4 can change the number of devices or the size of individual > devices. It cannot be converted to RAID5 yet (though that should be > trivial to implement)" I guess the man page needs updating. You would need a reasonably recen= t kernel... 2.6.30 or later. I guess that isn't so recent any more. NeilBrown >=20 > On 2 September 2011 11:22, NeilBrown wrote: > > On Fri, 2 Sep 2011 10:12:32 +0100 Michael Busby > > wrote: > > > >> Thanks Neil > >> > >> Is there anyway back from raid0 to raid4 as i know once at raid0 i > >> will no longer be able to add any disks, in theory i could change > >> echo raid0 > /sys/block/md0/md/level,but this would require adding= a > >> missing disk to the raid4 at the same time, not sure how easy that > >> would be todo > >> > > > > Yes, you can switch from RAID0 to RAID4 in much the same way as you= switch > > from RAID4 to RAID0. > > You can then freeze/add-disk/change-size/unfreeze/wait/switch-back-= to-RAID0 > > to add more devices. > > > > mdadm-3.2.2 should be able to do all this for you. =A0i.e. you ask = it to --grow > > a RAID and --add some disks at the same time, and it will do all th= e required > > magic. > > > > This hasn't been tested extensively, but should work in simple case= s. > > > > Of course the more devices you have in a RAID0, the less reliabilit= y you have > > - but e.g. as a cache for a tape backup system a large RAID0 is fin= e. > > > > NeilBrown > > > > > > -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html