Ah, die Ursache scheint #ZFS zu sein, das < 63 Zeichen für die Länge des Namens eines #Zvol empfiehlt… Ich dachte, das Z in ZFS steht dafür, dass es das letzte benötigte Dateisystem ist, aber dann scheitert es an 63 Zeichen 🙄

@ianthetechie
c 2018 #FreeBSD Wiki article creates #ZVol of specific size beforehand (sans vm-bhyve):
#bhyve Container Linux Virtual Machines, https://wiki.freebsd.org/bhyveContainerLinux?highlight=%28zvol%29%7C%28bhyve%29

... elsewhere used "truncate" to set the size of "*.img" (https://wiki.freebsd.org/bhyve/OpenBSD ). "vm-bhyve" could be using "truncate" somewhere unless hardcoded otherwise.

@technotim I have not used #ZVol #ZFS_volume, or iSCSI for that matter, yet. Learned, perhaps again, that for a #snapshot on a #ZFS volume, need to have free space of the same size as amount of currently "referenced" data. #noteToSelf

(I was going to ask why "zfs send | zfs recv" did not work, as I use myself that often. Mitch H's comment (on Youtube, https://www.youtube.com/watch?v=Uzk6Janio0g&lc=UgxaSmibJJtf_075cF54AaABAg.9ksHAkb6VVj9ksHiEL29G4) reminded me that that was due to lack of snapshot. D'oh!)