On 24/10/18 12:22 am, Daniel Koch wrote: > mdadm -C /dev/md2 -R -l6 -e 1.2 -n4 missing missing /dev/sda3 /dev/sdb3 > --assume-clean > > are you sure that's the right order ? the order of the disks is really > important here. a wrong order would result in the error you have > mentioned. try different orders here and then mount. this won't change > any data on the disks so you can do this without restoring your dd images. Yes, I checked the UUID of the partitions several times before creating the new array. However, what I didn't tell you earlier is that I had connected the drives to my Sabayon Linux notebook when issuing the command (the partitions were actually sdb3 and sdc3 there...I changed that in the original post to not create additional confusion). Now reading below in Wol's post that the defaults changed over time, maybe that was exactly the issue and create did not use the same defaults on my notebook than what would have been used by the Synology DiskStation. Hoping that the copies are not trash yet, I will re-try the create command with the DiskStation. Otherwise I will create new copies. I'll get access to the original disks only over the weekend and was hoping I could play around with the clones in the meantime; will post some details about the original drives/RAID once I have access on the weekend. Thanks for now! Regards, CygX1 > > Am 23. Oktober 2018 23:25:34 MESZ schrieb Wols Lists > <antlists@xxxxxxxxxxxxxxx>: > > Okay. I think you've done almost everything right, but not quite ... > > You've still got your original disks. Great. However, I think you've > just trashed your copies, so you'll need to re-copy them :-( > > Once you've got new copies, try putting an overlay over them, and then > do an "assemble force". > > There's no danger of them re-sync'ing (always the risk with --force) > because you've got no redundancy. But it should then put the disks back, > in their correct positions in the array, with all the offsets right. > > The trouble (which I suspect is why your Synology can't find a > superblock or anything) with re-creating an array is that the defaults > have changed over time, and if you've played around at all with the > disks, nothing will be in the default position anyway. So your > re-creation could well have moved the disks around in the array such > that what was your data-2 drive is now the P-drive etc etc. And your > data may well start at offset X whereas the new default is for it to be > at offset Y so the raid code is looking in the wrong place. Also etc etc... > > I could be wrong - I've got mostly head knowledge and not experience - > but that's the first thing I would suspect. > > If it works with the overlays, reboot or otherwise tear it all down, and > re-do it without the overlays. The point of overlaying is that you can > experiment and all the changes are written to ram and not disk, so you > don't trash the copies and have another frustrating X hours recreating > new copies. > Yes, creating the copies takes 8 days via USB 3.0 :-( -> that's actually the reason I copied just two drives and not the complete set of 4. I think I had tried a forced assemble prior to trashing? the clones with --create, but if I remember correctly "assemble --force" complained about superblocks as well. Could be wrong, though, as I didn't save the output and will re-try with the the overlay once the new copies are ready. > Oh - and *do* download lsdrv, and run it over the *original* disks. > Should things really go pear-shaped, that information will be invaluable. > Will do, thanks!
