On Mon, 9 Jul 2012 00:45:08 +0200 Alexander Schleifer <alexander.schleifer@xxxxxxxxxxxxxx> wrote: > 2012/7/9 NeilBrown <neilb@xxxxxxx>: > > On Sun, 8 Jul 2012 23:47:16 +0200 Alexander Schleifer > > <alexander.schleifer@xxxxxxxxxxxxxx> wrote: > > > >> Hi, > >> > >> after a new installation of Ubuntu, my RAID5 device was set to > >> "inactive". All devices were set to spare device and the level was > >> unknown. So I tried to re-create the array by the following command. > > > > Sorry about that. In case you haven't seen it, > > http://neil.brown.name/blog/20120615073245 > > explains the background > > > >> > >> mdadm --create /dev/md0 --assume-clean --level=5 --raid-disk=6 > >> --chunk=512 --metadata=1.2 /dev/sde /dev/sdd /dev/sda /dev/sdc > >> /dev/sdg /dev/sdh > >> > >> I have a backup of the mdadm -Evvvvs output, so I could recover the > >> chunk size, metadata and offset (2048) from this information. > >> > >> The partially output of mdadm --create... shows this output: > >> > >> ... > >> mdadm: /dev/sde appears to be part of a raid array: > >> level=raid5 devices=6 ctime=Sun Jul 8 23:02:51 2012 > >> mdadm: partition table exists on /dev/sde but will be lost or > >> meaningless after creating array > >> ... > >> > >> The array is recreated, but no valid filesystem is found on /dev/md0 > >> (dumpe2fs: Filesystem revision too high while trying to open /dev/md0. > >> Couldn't find valid filesystem superblock.). Also fdisk /dev/sde shows > >> no partition. > >> My next step would be creating Linux RAID type partitions on the 6 > >> devices with fdisk and call mdadm --create with /dev/sde1 /dev/sdd1 > >> and so on. > >> Is this step a possible solution for recovering the filesystem? > > > > Depends.. Was the original array created on partitions, or on whole devices? > > The saved '-E' output should show that. > > > > Maybe you have the devices in the wrong order. The order you have looks odd > > for a recently created array. > > > > NeilBrown > > The original array was created on whole devices, as the saved output > starts with e.g. "/dev/sde:". Right, so you definitely don't want to create partitions. Maybe when mdadm reported "partition table exists' it was a false positive, or maybe old information - creating a 1.2 array doesn't destroy the partition table. > I used the order of the 'Device UUID' from the saved output to > recreate the order in the new system (the ports changed due to a new > mainboard). When you say "the order", do you mean the numerical order? If you looked at the old "mdadm -E" output matching the "Device Role" with "Device UUID" to determine the order of the UUIDs, then looked at the "mdadm -E" output after the metadata got corrupted and used the "Device UUID" to determine the correct "Device Role", then ordered the devices by that Role, then that should have worked. I assume you did have a filesystem directly on /dev/md0, and hadn't partitioned it or used LVM on it? NeilBrown > After the installation I had a degraded array in > initramfs, but I was able to simply "exit" the debug shell and the > array was accessible. I will now skip the step of creating raid type > partitions and try every possible order of devices. > > Thanks, > -Alex
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