Upsizing a ZFS filesystem - shift question

I have an existing 32TB filesystem (2 X 8T vdevs). I want to upgrade each of the drives to 16TB. I pulled one drive and tried a ‘zfs replace’ comand, but zfs replied with some message about new drive
optimal ashift doesn’t match the vdev. It suggested Retrying  the ‘replace’ command with ‘zfs replace -o ashift=N’

Ok, a little investigation shows the existing filesystem has an ashift of 9. These are older 2T drives with 512 byte sectors. The newer drives are 4kn sectors.

Is ashift settable on a drive by drive basis? Can I temporarily set ashift on a drive until all the drives in a vdev have been replaced?  Once all drives have been replaced, how do I set ashift=12 for all the drives in the vdev?

After replacing all the drives, will the additional space magicially appear or is there an additional command or series of steps?

Thanks,

Joe

Joe McGuckin
ViaNet Communications

joe@via.net
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