> I have a 4 disk raid 5 array on my Ubuntu 10.10 box. They are /dev/sd[c,d,e,f]. Smartctl started notifying me that /dev/sde had some bad sectors and the number of errors was increasing each day. To mitigate this I decided to buy a new drive and replace it. > > I failed /dev/sde via mdadm: > > mdadm --manage /dev/md0 --fail /dev/sde > mdadm --manage /dev/md0 --remove > > I pulled the drive from the enclosure . . . and found it was the wrong drive (should have been the next drive down . . .). I quickly pushed the drive back in and found that the system renamed the device (/dev/sdh). > I then tried to add that drive back in (this time with the different dev name): > > mdadm --manage /dev/md0 --re-add /dev/sdh > (I don't have the output of --detail for this step.) > > I rebooted and the original dev name returned (/dev/sdd). > > The problem is now I have two drives in my raid 5 which of course won't start: > > mdadm -As /dev/md0 > mdadm: /dev/md0 assembled from 2 drives and 2 spares - not enough to start the array. > > > Although, I can get it running with: > dadm --incremental --run --scan > > So my question is how can I add these two still-valid spares back into my array? > > Here is the output of mdadm --detail /dev/md0: > > /dev/md0: > Version : 00.90 > Creation Time : Thu May 27 15:35:56 2010 > Raid Level : raid5 > Used Dev Size : 732574464 (698.64 GiB 750.16 GB) > Raid Devices : 4 > Total Devices : 4 > Preferred Minor : 0 > Persistence : Superblock is persistent > > Update Time : Fri Mar 11 15:53:35 2011 > State : active, degraded, Not Started > Active Devices : 2 > Working Devices : 4 > Failed Devices : 0 > Spare Devices : 2 > > Layout : left-symmetric > Chunk Size : 64K > > UUID : 11c1cdd8:60ec9a90:2e29483d:f114274d (local to host storage) > Events : 0.43200 > > Number Major Minor RaidDevice State > 0 8 80 0 active sync /dev/sdf > 1 0 0 1 removed > 2 0 0 2 removed > 3 8 32 3 active sync /dev/sdc > > 4 8 64 - spare /dev/sde > 5 8 48 - spare /dev/sdd > > > I appreciate any help. > > Matt I did find one older thread with a similar problem. The thread was titled " RAID 5 re-add of removed drive? (failed drive replacement)" The point that seemed to make the most sense is: AFAIK, the only solution at this stage is to recreate the array. You need to use the "--assume-clean" flag (or replace one of the drives with "missing"), along with _exactly_ the same parameters & drive order as when you originally created the array (you should be able to get most of this from mdadm -D). This will rewrite the RAID metadata, but leave the filesystem untouched. The question I have is how do I know what order to put the drives in? And is this really the route I need to take? -- 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
