From mboxrd@z Thu Jan 1 00:00:00 1970 From: Veljko Subject: Re: Linear device of two arrays Date: Fri, 21 Jul 2017 11:15:37 +0200 Message-ID: References: <20170705214250.0ea99538@natsu> <595D2ADA.8010907@youngman.org.uk> <5afd5cea-06b8-8524-e4f5-8534f23bd714@hardwarefreak.org> <87van15j9b.fsf@notabene.neil.brown.name> <87o9sn232n.fsf@notabene.neil.brown.name> <1eefd627-1aba-a795-05f0-d2106d3a62a3@gmail.com> <87shhyzhg5.fsf@notabene.neil.brown.name> <38e015fa-a07c-8f1a-3a04-384d973966be@gmail.com> <87d18uydir.fsf@notabene.neil.brown.name> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <87d18uydir.fsf@notabene.neil.brown.name> Sender: linux-raid-owner@vger.kernel.org To: NeilBrown , linux-raid@vger.kernel.org List-Id: linux-raid.ids On 07/21/2017 12:00 AM, NeilBrown wrote: > On Mon, Jul 17 2017, Veljko wrote: > >> On 07/15/2017 02:12 AM, NeilBrown wrote: >> >>> So command should be >>> >>>>> dd if=/dev/md2 of=SOMEWHERE/SAFE bs=1M skip=5626590 >>> >>> and expect it to create a 3M file. >>> >>> Use this 'skip' number of the 'seek' number later. >>> >>> NeilBrown >> >> Thanks, Neil, now it makes more sense. >> >> I tried to create new linear device, but mdadm is complaining about >> data-offset: >> >> # mdadm -C /dev/md4 -l linear -n 2 --rounding=1M -e 1.0 --data-offset=0 >> /dev/md2 /dev/md3 >> mdadm: invalid data-offset: 0 > > Bother. > mdadm uses "parse_size()" to parse the offset, and this rejects > "0", which makes sense for a size, but not for an offset. > > Just leave the "--data-offset=0" out. I checked and that is defintely > the default for 1.0. > >> I noticed that md2 and md3 use 1.2 metadata. Can that be the issue? > > No the metadata on md4 is quite independent of the metadata on md2 and md3. > > NeilBrown Yes, now it works. I was able to create new linear device, restored the saved 3M file and grown xfs. It was really fast and indeed, I'm happy. Thank you very much, Neil! Regards, Veljko