From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Busby Subject: Re: Raid5 to another raid level?? Date: Fri, 2 Sep 2011 14:11:57 +0100 Message-ID: References: <-7094796685559591664@unknownmsgid> <20110902121959.173a1aa9@notabene.brown> <20110902202235.0194d779@notabene.brown> <20110902224938.74c30811@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20110902224938.74c30811@notabene.brown> Sender: linux-raid-owner@vger.kernel.org To: NeilBrown Cc: john.robinson@anonymous.org.uk, linux-raid@vger.kernel.org List-Id: linux-raid.ids I am using the 3.0.0 kernel so that should not be a issue, have just upgraded mdadm on my box to 3.2.2 from 3.1.4 would i be right in thinking that to get from raid0 to raid5 i would first have to change from raid0 to raid4 and add the extra disk for parity, once i am at this level i would need a command to get the parity data striped over the raid5 and not in a single disk like raid4 or maybe there is a way to go from raid0 direct to raid5 by adding the extra disk and then having the parity data created and spread over the disks.... On 2 September 2011 13:49, NeilBrown wrote: > On Fri, 2 Sep 2011 11:35:30 +0100 Michael Busby > wrote: > >> Great, will test that in a bit >> >> will mdadm 3.2.2 support converting raid4 to raid5 >> >> "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. =A0You would need a reasonably r= ecent > kernel... 2.6.30 or later. =A0I guess that isn't so recent any more. > > NeilBrown > > >> >> 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 addin= g a >> >> missing disk to the raid4 at the same time, not sure how easy tha= t >> >> would be todo >> >> >> > >> > Yes, you can switch from RAID0 to RAID4 in much the same way as yo= u 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 t= he required >> > magic. >> > >> > This hasn't been tested extensively, but should work in simple cas= es. >> > >> > Of course the more devices you have in a RAID0, the less reliabili= ty you have >> > - but e.g. as a cache for a tape backup system a large RAID0 is fi= ne. >> > >> > 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