久しぶりにsshログインして、zpool statusを見たら、
こんな表示が．．．

status: The pool is formatted using an older on-disk format. The pool can
still be used, but some features are unavailable.
action: Upgrade the pool using 'zpool upgrade'. Once this is done, the
pool will no longer be accessible on older software versions.

>Once this is done, the pool will no longer be accessible on older software versions.
が怖くて、zpool upgradeする決心がつきません．．．