BTW as to in general this question: > which one is the safest ? That would be the first option I presented, where the 3x 4TB disks get split in two, and the existing 3 2TB slices get copied onto them, as I wrote: > The least scary option might be: > > * Split into two partitions D and E. > * Block copy the image on C to D1 and E2. > * Re-partition C also in two. > * Block copy B to C1. > * Block copy A to E2. > * Now we have greatly increased redundancy, as we have the 3x > 2TB data slices on two separate sets, A, C1, D1 and D2, B, > E2. That is about as good as it gets as to safety with the limited number of drives in play. BTW note that it is really important not to start the second copy, because it has the same set and member UUIDs as the other one. But the O.P. must be a very experienced RAID specialist, or he would not be trying to do subtle device restructuring like this. > * Add E1 as a spare to the A, C1, D1 RAID5 set, and start it so > you end up with a full RAID5 set on A, C1, D1, E1 after > resync end. This resync is less dangerous because we have a full (if degraded) copy of the data on D2, B, E2. With an extra 4TB drive, even a temporary one, to hold an offline backup (if the 4.5TB can be compressed to fit), more dangerous options become less scary. > * Now that the first RAID5 set is not degraded, you can erase > the copies on D2, B, E2, and create a second RAID5 set on > B, C2, D2, E2, which will be empty. -- 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
