RAIDZ1 to RAIDZ2 without doubling drives

TrueNAS General
2

Create the new Z2 array with 3 new disks PLUS a sparse zvol, removing the zvol after array creation to create a degraded array (acting as a Z1). This will give you 16TB whilst maintaining parity in both arrays

Then use old disks, once data is transferred to:

  1. Replace missing disk to “upgrade” the array back to Z2
  2. Add disks, one by one to the pool to increase capacity
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