Am Wed, Sep 06, 2023 at 02:45:11PM -0500 schrieb Dale:

> Oh, creating a
> vdev was the trick.  Once that is done, expand the pool.  It's one of
> those, once it is done, it seems easy.  ROFL

Note that people used to shoot themselves in the foot when lazily (or by 
accident) adding a single disk to an existing pool. If that pool was 
composed of RAID vdevs, then now they had a non-redundant single disk in 
that pool and it was not possible to remove a vdev from a pool! That 
single-disk vdev could only be converted to a mirror to at least get 
redundancy back.

The only proper solution was to destroy the pool and start from scratch. By now there is a partial remedy, in that it is possible to remove mirror vdevs from a pool. But no RAIDs:
https://forum.level1techs.com/t/solved-how-to-remove-vdev-from-zpool/192044/5
https://arstechnica.com/civis/threads/performance-when-removing-zfs-vdevs-with-zpool-remove.1481148/post-40491873
And you get some left-over metadata about the removed vdev.

> I guess vdev is like LVMs pv, physical volume I think it is.

Haven’t we had this topic before? At least twice? Including the comparison between 
the three layers of LVM with their equivalent in ZFS land. ;-)

ZFS is more meant for static setups, not constantly changing disk loadouts 
of varying disk sizes.

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