Help understanding pool size after vdev expansion

TrueNAS General
,
1

RAIDZ2, 1 vdev, 6-wide 12TB.

Started with 4 12TB drives, and since replaced one (first and only resilver), and expanded the vdev, adding 2 drives recently, for a total of 6.

Screenshot 2025-04-04 at 2.33.49 PM
Screenshot 2025-04-04 at 2.33.49 PM1013×319 32.9 KB

Screenshot 2025-04-04 at 2.33.56 PM
Screenshot 2025-04-04 at 2.33.56 PM629×308 15.9 KB

root@nas1[~]# zpool list pool1
NAME    SIZE  ALLOC   FREE  CKPOINT  EXPANDSZ   FRAG    CAP  DEDUP    HEALTH  ALTROOT
pool1  65.5T  8.15T  57.3T        -         -     6%    12%  1.00x    ONLINE  /mnt
root@nas1[~]# zpool status pool1 -v
  pool: pool1
 state: ONLINE
  scan: scrub repaired 352K in 03:54:59 with 0 errors on Fri Apr  4 03:10:03 2025
expand: expanded raidz2-0 copied 7.99T in 11:08:26, on Thu Apr  3 01:52:58 2025
config:

	NAME                                      STATE     READ WRITE CKSUM
	pool1                                     ONLINE       0     0     0
	  raidz2-0                                ONLINE       0     0     0
	    8d977df4-68d2-424a-b9f2-5368f111bd34  ONLINE       0     0     0
	    sdd2                                  ONLINE       0     0     0
	    sdg2                                  ONLINE       0     0     0
	    sdh2                                  ONLINE       0     0     0
	    11ea30fd-ed9b-4ef8-8931-dec798f8ca30  ONLINE       0     0     0
	    299865cb-98fa-4359-ad04-2dcf3171caa2  ONLINE       0     0     0

errors: No known data errors

I would have expected to see ~40TB useable, rather than ~32TB per ZFS Capacity Calculator | TrueNAS Documentation Hub.

Have I missed something? If so, would appreciate an education. Thanks!

2

there’s already a pretty lengthy discussion reagarding the space discrepancy

3

Ah, I had seen that (or a thread similar), and assumed my discrepancy was a result of misunderstanding useable post expansion. Thanks!