In the meantime, did a bit more tinkering to see if I could further troubleshoot. Turns out that, if I do a fresh 9.3 install on my main box, CIFS starts just fine BEFORE I import my volume. Once I import it though, it doesn't start anymore. Weird...?
Here's the testparm results (BTW, as per documentation, it's /smb4.conf, not /smb.conf) :
testparm /usr/local/etc/smb4.conf
Load smb config files from /usr/local/etc/smb4.conf
Processing section "[homes]"
Processing section "[MainBackup]"
Loaded services file OK.
WARNING: lock directory /var/db/samba4 should have permissions 0755 for browsing to work
WARNING: state directory /var/db/samba4 should have permissions 0755 for browsin g to work
WARNING: cache directory /var/db/samba4 should have permissions 0755 for browsin g to work
Server role: ROLE_STANDALONE
Press enter to see a dump of your service definitions
[global]
dos charset = CP437
server string = FreeNAS Server
server role = standalone server
map to guest = Bad User
null passwords = Yes
obey pam restrictions = Yes
smb passwd file = /var/etc/private/smbpasswd
private dir = /var/etc/private
max log size = 51200
server max protocol = SMB2
time server = Yes
deadtime = 15
max open files = 227738
load printers = No
printcap name = /dev/null
disable spoolss = Yes
dns proxy = No
pid directory = /var/run/samba
panic action = /usr/local/libexec/samba/samba-backtrace
nsupdate command = /usr/local/bin/samba-nsupdate -g
idmap config *: range = 90000001-100000000
idmap config * : backend = tdb
acl allow execute always = Yes
create mask = 0666
directory mask = 0777
ea support = Yes
directory name cache size = 0
kernel change notify = No
store dos attributes = Yes
strict locking = No
dfree command = /usr/local/libexec/samba/dfree
dos filemode = Yes
[homes]
comment = Home Directories
valid users = %U
read only = No
veto files = /.snapshot/.windows/.mac/.zfs/
vfs objects = aio_pthread, streams_xattr
zfsacl:acesort = dontcare
nfs4:chown = true
nfs4:acedup = merge
nfs4:mode = special
recycle:subdir_mode = 0700
recycle:directory_mode = 0777
recycle:touch = yes
recycle:versions = yes
recycle:keeptree = yes
recycle:repository = .recycle/%U
[MainBackup]
path = /mnt/Raidz2
read only = No
guest ok = Yes
hide dot files = No
veto files = /.snapshot/.windows/.mac/.zfs/
vfs objects = shadow_copy2, zfsacl, aio_pthread, streams_xattr
zfsacl:acesort = dontcare
nfs4:chown = true
nfs4:acedup = merge
nfs4:mode = special
shadow:snapdirseverywhere = yes
shadow:format = auto-%Y%m%d.%H%M-1w
shadow:localtime = yes
shadow:sort = desc
shadow:snapdir = .zfs/snapshot
recycle:subdir_mode = 0700
recycle:directory_mode = 0777
recycle:touch = yes
recycle:versions = yes
recycle:keeptree = yes
recycle:repository = .recycle/%U
