You forgot IDEA #6 where you take advantage of the fact that zfs can
be told to use sparse files as partitions. This is rather like your
IDEA #3 but does not require that disks be partitioned.
This opens up many possibilities. Whole vdevs can be virtualized to
files on (i.e. moved onto) remaining physical vdevs. Then the drives
freed up can be replaced with larger drives and used to start a new
pool. It might be easier to upgrade the existing drives in the pool
first so that there is assured to be vast amounts of free space and
the drives get some testing. There is not initially additional risk
due to raidz1 in the pool since the drives will be about as full as
I am not sure what additional risks are involved due to using files.
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
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