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 > > I'm using Debian 8.8 if it makes any difference. > > # mdadm -V > mdadm - v3.3.2 - 21st August 2014 > > What could be the problem? > > Regards, > Veljko > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html
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