-fun-
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- Oct 27, 2015
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- 171
I about to build a 4 drive RAIDZ2 pool. Now it seems a pool of 2 mirrored vdevs may be an option as well. I got a recommendation (sorry, I lost the source), that the replacement of a failed drive would be much much quicker than in a RAIDZ2. The long duration of a drive replacement in a RAIDZ2 would decrease the overall reliability of the RAIDZ2.
Is that true?
The RAIDZ2 option should provide higher reliability: It will survive the loss of up to any two drives while a pool with 2 mirrored vdevs will die on failure of 2 drives depending on which drives fail.
Other aspects to consider:
Is that true?
The RAIDZ2 option should provide higher reliability: It will survive the loss of up to any two drives while a pool with 2 mirrored vdevs will die on failure of 2 drives depending on which drives fail.
Other aspects to consider:
- Capacity: No difference in this case (4 drives of equal capacity).
- Performance: The Guide claims improved performance of mirrored vdevs in specific scenarios (not the most important aspect for me though).
- The mirrored vdevs have another advantage: The migration is much easier because I can create a pool of one mirrored vdev, migrate data to this, wipe the existing drive, create another mirrored vdev of the existing drive and another new drive and expand the pool with this. (I'm limited to 4 drive bays ...)
- Also mirrored vdevs should make it easier to expand capacity in the future: I can replace 2 drives of one vdev with larger drives and thus increase the pool size. With a RAIDZ2 this would require the replacement of all drives.