zpool.cache do not survive after a zpool export

[William J. Franck]

Context

• 1 pool created with a file vdev.

Short story

1. sudo zpool import -aor sudo zpool import -d /vdev 554310920175130116
2. /etc/zfs/zpool.cache is created (or updated)
3. sudo zpool export -a[f]
zpool.cache disappears

consequences :
zpool.cache can not be used at boot-time

Note : FreeBSD keeps this file troughout exports or reboots.

Config
MacBookAir (2012) with SSD (APFS) - macOS 10.14.6 (18G4032)/ Darwin 18.7.0
sysctl {spl,zfs}.kext_version

spl.kext_version: 1.9.4-0
zfs.kext_version: 1.9.4-0

[William J. Franck]

Strange !

• after a zpool export [-a | pool_name] , /etc/zfs/zpool.cache vanished (deleted, moved ?)
• while rebooting, launchd of *...zpool-import-all.plist do find the cache file !!

Question : was it recreated by some memory dump of the actual in-memory cache?

See log file *...zpool-import-all.log
(with a zpool list`in the import-all.plist.sh )

Running zpool import -c /etc/zfs/zpool.cache -a
Finished running zpool import from cache : 0
NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT
zTest 480M 347M 133M - - 38% 72% 1.00x ONLINE -