Capacity discrepancy after expanding RAIDZ1

Hello,

This is my first post, and I’m not entirely sure if I’m following the correct procedure, so please let me know if I need to provide more information. Also, English is not my first language, so I apologize if there are any mistakes.

I recently expanded my pool from 3×12 TB to 9×12 TB in a single RAIDZ1 configuration, but the system only reports about 65.28 TB of usable space. Could you please confirm whether this is normal behavior? If this is expected, any guidance on how the final usable capacity is calculated or best practices to optimize the storage would be greatly appreciated.

Is this normal?

Best regards,

zpool status

  pool: DATA
 state: ONLINE
  scan: resilvered 988M in 00:00:06 with 0 errors on Sat Feb  8 20:47:36 2025
expand: expanded raidz1-0 copied 69.2T in 5 days 02:51:54, on Sat Oct 26 12:17:11 2024
config:

        NAME                                      STATE     READ WRITE CKSUM
        DATA                                      ONLINE       0     0     0
          raidz1-0                                ONLINE       0     0     0
            1445e11f-5ee5-4f22-a97c-0d4d3bdfcda2  ONLINE       0     0     0
            8ab510e3-713b-467e-84f2-27de4bb97008  ONLINE       0     0     0
            1d481850-2ae7-46a8-890b-848466ad7b58  ONLINE       0     0     0
            7451163e-bc0a-4f38-8d3c-014fb6c13901  ONLINE       0     0     0
            3b215c29-3d55-406f-94a5-6cbf5c4fb773  ONLINE       0     0     0
            5f455019-0ade-47af-a6be-7fc7dcb847b9  ONLINE       0     0     0
            2be2314b-f882-4a4a-acee-85075717ef7a  ONLINE       0     0     0
            196cc14e-1320-459d-8236-2f942cad2f54  ONLINE       0     0     0
            14fd2d0e-4aaf-4b98-9697-8af0e21b4d66  ONLINE       0     0     0

errors: No known data errors

zfs get all DATA

NAME  PROPERTY              VALUE                  SOURCE
DATA  type                  filesystem             -
DATA  creation              Sun Apr 30 18:25 2023  -
DATA  used                  60.0T                  -
DATA  available             5.32T                  -
DATA  referenced            139K                   -
DATA  compressratio         1.00x                  -
DATA  mounted               yes                    -
DATA  quota                 none                   default
DATA  reservation           none                   default
DATA  recordsize            128K                   default
DATA  mountpoint            /mnt/DATA              default
DATA  sharenfs              off                    local
DATA  checksum              on                     default
DATA  compression           lz4                    local
DATA  atime                 off                    local
DATA  devices               on                     default
DATA  exec                  on                     default
DATA  setuid                on                     default
DATA  readonly              off                    default
DATA  zoned                 off                    default
DATA  snapdir               hidden                 default
DATA  aclmode               discard                local
DATA  aclinherit            discard                local
DATA  createtxg             1                      -
DATA  canmount              on                     default
DATA  xattr                 on                     default
DATA  copies                1                      default
DATA  version               5                      -
DATA  utf8only              off                    -
DATA  normalization         none                   -
DATA  casesensitivity       sensitive              -
DATA  vscan                 off                    default
DATA  nbmand                off                    default
DATA  sharesmb              off                    local
DATA  refquota              none                   default
DATA  refreservation        none                   default
DATA  guid                  565392711373990559     -
DATA  primarycache          all                    default
DATA  secondarycache        all                    default
DATA  usedbysnapshots       0B                     -
DATA  usedbydataset         139K                   -
DATA  usedbychildren        60.0T                  -
DATA  usedbyrefreservation  0B                     -
DATA  logbias               latency                default
DATA  objsetid              54                     -
DATA  dedup                 off                    default
DATA  mlslabel              none                   default
DATA  sync                  standard               default
DATA  dnodesize             legacy                 default
DATA  refcompressratio      1.00x                  -
DATA  written               139K                   -
DATA  logicalused           74.9T                  -
DATA  logicalreferenced     46K                    -
DATA  volmode               default                default
DATA  filesystem_limit      none                   default
DATA  snapshot_limit        none                   default
DATA  filesystem_count      none                   default
DATA  snapshot_count        none                   default
DATA  snapdev               hidden                 default
DATA  acltype               posix                  local
DATA  context               none                   default
DATA  fscontext             none                   default
DATA  defcontext            none                   default
DATA  rootcontext           none                   default
DATA  relatime              on                     default
DATA  redundant_metadata    all                    default
DATA  overlay               on                     default
DATA  encryption            off                    default
DATA  keylocation           none                   default
DATA  keyformat             none                   default
DATA  pbkdf2iters           0                      default
DATA  special_small_blocks  0                      default
DATA  prefetch              all                    default

Version: TrueNAS SCALE ElectricEel-24.10.2

Space reporting after expansion is wrong.

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Thank you for your response! If I understand correctly, this behavior is normal and it’s just the interface displaying some unexpected values, but the actual capacity is accurate. I appreciate your clarification.

Thanks

3x12TB RAIDZ1 is fine.

9x12TB RAIDZ1 really should be RAIDZ2.

2 Likes