Hi!
I'm finally planning to retire my 8x1TB RaidZ2+spare array of more-than-a-decade-old Seagate Barracuda drives. My plan is to start with three 18 TB WD Ultrastar DC HC550 drives set up as a 3-way mirror and then, if I need additional storage, to add a fourth drive and convert the pool into RaidZ2.
If I understand things correctly, it should be possible to transform a 3-disk mirror to a 4-disk RaidZ2 without additional (temporary) storage and while still keeping at least two copies of the data at all times (i.e. allowing for one drive failure during the transformation). This is what I plan to do:
1. Remove one disk from the 3-disk mirror
2. Create a de-graded (2 drives missing) RaidZ2 on the new disk and the disk removed from the mirror
3. Copy all data from the (now) 2-disk mirror to the de-graded RaidZ2
4. Remove one more disk from the 2-disk mirror and add it to the de-graded RaidZ2. Wait for the pool to re-silver.
5. Clear the last disk from the mirror and add it to the de-graded RaidZ2 (which after re-silvering will no longer be de-graded)
Would this work, or am I missing something important here?
Thank you in advance!
Ps. I know I could set up a 3-disk RaidZ2 and use raidz expansion when adding the fourth disk. This would, however, mean a loss of capacity due to the existing data keeping its 2:1 parity to data ratio. Ds.
I'm finally planning to retire my 8x1TB RaidZ2+spare array of more-than-a-decade-old Seagate Barracuda drives. My plan is to start with three 18 TB WD Ultrastar DC HC550 drives set up as a 3-way mirror and then, if I need additional storage, to add a fourth drive and convert the pool into RaidZ2.
If I understand things correctly, it should be possible to transform a 3-disk mirror to a 4-disk RaidZ2 without additional (temporary) storage and while still keeping at least two copies of the data at all times (i.e. allowing for one drive failure during the transformation). This is what I plan to do:
1. Remove one disk from the 3-disk mirror
2. Create a de-graded (2 drives missing) RaidZ2 on the new disk and the disk removed from the mirror
3. Copy all data from the (now) 2-disk mirror to the de-graded RaidZ2
4. Remove one more disk from the 2-disk mirror and add it to the de-graded RaidZ2. Wait for the pool to re-silver.
5. Clear the last disk from the mirror and add it to the de-graded RaidZ2 (which after re-silvering will no longer be de-graded)
Would this work, or am I missing something important here?
Thank you in advance!
Ps. I know I could set up a 3-disk RaidZ2 and use raidz expansion when adding the fourth disk. This would, however, mean a loss of capacity due to the existing data keeping its 2:1 parity to data ratio. Ds.