Makes sense.
That’s a tricky decision, it depends on how bad was the fault on the drive: a few reallocated sectors? Let it resilver.
5 drives in RAIDZ1, even with a lightly faulted one, is still better than a degraded RAIDZ1 VDEV with only 4 drives and no parity.
RAIDZ1 gives you the ability to withstand a single drive failure amongst the ones in the VDEV: if we increase the number of drives in the VDEV, we increase the chances of more than one drive failing at the same time.
Then you could also go with 3x 5-wide RAIDZ2 VDEVS and a single hotspare. It depends on your requirements.
Basically yes, the pool will be able to withstand up to 2 drive failures per VDEV at the same time.
Each VDEV will be able to withstand up to 7 drive failures, but the available space will only be 1/8 of your drives. At that point, it would likely be better to go with 4x 4-way mirrors if you need the resiliency and performance (do note that this is an incredibily resilient layout, likely eccessive for anything but mission-critical enterprise/government data). If you need a 8-way mirror level of redundancy, you should consider professional alternatives to home storage.
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