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Apr 29, 2019 · LVM and mdadm / dmraid are both offering software RAID functionality on Linux. This is pretty much a follow-up post to this question from 2014. Back then, @derobert recommends to prefer mdadm over LVM raid for it's matureness - but that was over 4 years ago. I can imagine, things have changed since then.

sudo mdadm --detail /dev/md0 State : clean, degraded Number Major Minor RaidDevice State 0 0 0 0 removed 1 8 32 1 active sync /dev/sdc 3 8 48 2 active sync /dev/sdd 0 8 16 - faulty spare /dev/sdb Details show us the removal of the first disk and here we can see the true order of the disks in the array.

Apr 26, 2017 · # mdadm --detail /dev/md0 /dev/md0: Version : 1.2 Creation Time : Fri Mar 2 15:14:46 2012 Raid Level : raid6 Array Size : 38654631936 (36863.93 GiB 39582.34 GB) Used Dev Size : 2147479552 (2048.00 GiB 2199.02 GB) Raid Devices : 20 Total Devices : 21 Persistence : Superblock is persistent Update Time : Wed Apr 25 19:47:09 2012 State : active ...

Well, mdadm --stop /dev/md0 might take care of your busy messages, I think that's why its complaining. Then you can try your assemble line again. If it doesn't work, --stop again followed by assemble with --run (without run, --assemble --scan won't start a degraded array). Then you can remove and re-add your failed disk to let it attempt a rebuild.

I hope you also realised that the old contents will be wiped in the process, so you might want to create a new array with one device missing (use mdadm --level=10 --raid-devices=8 --missing /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1 /dev/sdf1 /dev/sdg1 /dev/sdh1). Then format the filesystem on the new array volume and copy all data from /dev/sda1 ...

When I try the command mdadm --examine /dev/sda1, I can't seem to find "preferred superblocks" on version 1.2. This field shows up in metadata version 0.9. Is there a way to get such metadata information? Or is the output of mdadm --examine just the information I'm going to …

Apr 14, 2015 · The root variable is set to mduuid/xxx with the UUID of the RAID array which you can get by running mdadm --examine /dev/sdX on a disk or partition which is part of the RAID array. This is not the UUID of the EXT4 filesystem on top of the RAID , do not use the UUID reported by lsblk as it will only give you the UUID of the partition which won't ...

Apr 13, 2017 · It was suggested to me that the old superblocks of the raid arrays might be left behind causing MD to think it is a real array and thus binding the disks. The suggested solution was to use mdadm --zero-superblock to clear the superblock on the affected disks. However, I don't really know what this does with the disk.

Its currently mdadm RAID-1, going to RAID-5 once I have more drives (and then RAID-6 I'm hoping for). However I've heard various stories about data getting corrupted on one drive and you never noticing due to the other drive being used, up until the point when the first drive fails, and you find your second drive is also screwed (and 3rd, 4th ...