Dear Andreas, In message <20160515203446.GA13218@xxxxxxxxxxxxxxx> you wrote: > > That's strange, if it worked once, it should work twice (if no changes > were made outside of the overlays). If you have created the udev rules > file, just in case there is a side effect, remove it again ... NO, I think it's me to blame. If I read the bash history correctly, I made a mistake (confusing $DEVICES and $devices and $overlays) and ran the --zero-superblock on the real disk devices, not the overlays. On the other hand, that should not make a real difference if it worked for the overlays. Well, it does... > What does mdadm --examine /dev/mapper/sda say before and after > you --zero-superblock? (is it the same for the other disks?) --zero-superblock now porperly reports that it cannot find a superblock... > If it's LVM, you could search the first few hundred megs of your devices for > the LVM header, that should be the data offset you're looking for. Ok, but... > That's LABELONE at offset 0x200 and you have to substract 512 bytes from it, > so this is actually what it would look like for offset 0. That would be the --data-offset= parameter? > Alternatively this can also be done using > > dd bs=1M count=1024 if=... | strings -t d -n 8 | grep LABELONE > 512 LABELONE > > if your version of strings supports this option. It does - but I'm confused as I get a number of different values from the devices: # for i in /dev/mapper/sd? ; do > echo $i > dd bs=1M count=1024 if=$i | strings -t d -n 8 | grep LABELONE > done /dev/mapper/sda 139776 LABELONE ... /dev/mapper/sdb ... /dev/mapper/sdc 396826104 LABELONE ... /dev/mapper/sdd ... /dev/mapper/sde 387503608 LABELONE 389663524 LABELONE ... /dev/mapper/sdf 398969636 LABELONE ... So I have 5 numbers; minus 512 and converted to kB gives: 139776 -> 139264 -> 136 396826104 -> 396825592 -> 887524.99 387503608 -> 387503096 -> 878410.99 389663524 -> 389663012 -> 380530.28 398969636 -> 398969124 -> 889618.28 Of these, only 136 appears to make sense. But running # mdadm --create --verbose /dev/md2 --metadata=1.2 --level=6 --raid-devices=6 --chunk=16 --assume-clean --data-offset=136 /dev/mapper/sd? mdadm: layout defaults to left-symmetric mdadm: size set to 976762448K mdadm: automatically enabling write-intent bitmap on large array mdadm: array /dev/md2 started. ...creates an array, but LVM does not recognise it. Searching the resulting /dev/md2 for the LABELONE does not find any. Am I misinterpreting your information? Best regards, Wolfgang Denk -- DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@xxxxxxx The sixth sick sheik’s sixth sheep’s sick. -- 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
