Discovered during Phase 1.3 (mount NAS datastore). The Debian NAS's
/mnt/backup is on ZFS with casesensitivity=insensitive; NFSv4 writes
fail with EACCES even for root with no_root_squash. Known-bad
combination at the ZFS-on-Linux + NFSv4 layer.
Workaround: mount the NFS share with vers=3. PBS's chunk-based
access pattern works fine over NFSv3.
Added a section 0.5 to Phase 0 documenting the issue + both fixes
(quick: use NFSv3; cleaner: create case-sensitive child dataset).
Future deployments against this NAS won't rediscover the same wall.
vh
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