zpool autoexpand doesn't change size of pool

We have some old Solaris 10 servers (SunOS name 5.10 Generic_142909-17 sun4u sparc SUNW,Sun-Fire-V490) now connected to our new IBM SAN. These Solaris servers still have mostly UFS file systems. A while back, we added a new 2 TB LUN from the SAN to one of the servers and started using it as a zpool with one ZFS file system defined on it - really simple. It worked great!

Recently we found that 2 TB wasn't enough, so we extended the LUN from 2 TB to 3 TB. zpool list showed

NAME         SIZE  ALLOC   FREE    CAP  HEALTH  ALTROOT
solarisSYS  1.98T  1.84T   146G    92%  ONLINE  -

...both before and after the LUN was extended, as one would expect. luxadm display now shows

# luxadm display /dev/rdsk/c4t600507640081017A080000000000004Dd0s2
DEVICE PROPERTIES for disk: /dev/rdsk/c4t600507640081017A080000000000004Dd0s2
Vendor:               IBM     
Product ID:           2145            
Revision:             0000
Serial Num:           010020405e82XX00
Unformatted capacity: 3145728.000 MBytes
Read Cache:           Enabled
  Minimum prefetch:   0x0
  Maximum prefetch:   0x0
Device Type:          Disk device
Path(s):
/dev/rdsk/c4t600507640081017A080000000000004Dd0s2
/devices/scsi_vhci/ssd@g600507640081017a080000000000004d:c,raw

Various sources said to do these, which I did:

# zpool set autoexpand=on solarisSYS
# zpool online -e solarisSYS c4t600507640081017A080000000000004Dd0
# zpool export solarisSYS
# zpool import solarisSYS
# zpool list solarisSYS
NAME         SIZE  ALLOC   FREE    CAP  HEALTH  ALTROOT
solarisSYS  1.98T  1.84T   146G    92%  ONLINE  -

Does autoexpand not work for our old version of Solaris? Or is there something else I can try?

You may have export and reimport the pool or reboot and try the zpool online -e again.

This is definitely the case on Linux. But with your situation, it is worth a shot.

Normally you can't increase an actual disk's size, so zfs, or your version of zfs, may not have been designed/tested with that. Maybe you need to add a new LUN, use zpool replace pool olddisk newdisk instead, and then remove the old after.