Volume manager should allow mix-matching drives that are slightly different in size
The new volume manager groups disks by their size. It's desirable to provide 2 different options in advanced mode:
a) strict: each group can only contain disks that are exactly the same;
b) permissive: merge groups that are different by a threshold (1MB or a few MB?), this will be the new default;
The option do not necessarily be in the volume manager itself, e.g. this could be a system-wide option.
#1 Updated by Josh Paetzel about 8 years ago
Even when the size is identical, the grouping seems to happen solely based on size. If you have two disks that have the same number of blocks but are different they will be in the same group.
An extreme version of this was provided by mav@ where the system grouped an SSD with a 7.2k SATA hard drive.
#3 Updated by Craig Stevenson over 7 years ago
Please allow permissive to be truly permissive. Why not allow a vdev to use 500GB (existing drives) and a 1.5TB? Yes, part of the space is lost until the older drives are replenished. ZFS can handle this; and it will even support expanding the dvev to 1.5TB once the older 500GB are replaced by drives that are 1.5TB or larger.