Question: Mixing different disk sizes (WebUI vs terminal)

I’ve a question:

How come that if I use the WebUI to extend (attach) a drive that is bigger (12 TB) to a smaller one (10 TB), that the WebUI creates a different partition sizes and shows me “Mixed capacity” under storage?


If I use zpool attach in the terminal, the WebUI doesn’t report “Mixed capacity”.

From my understanding:
The WebUI uses the whole disk size for the partition, but the command only utilizes the size of the smaller device hence a smaller partition on the bigger disk?!

At least that’s what fdisk -l reports?!

admin@truenas[~]$ sudo fdisk -l /dev/sdf
Disk /dev/sdf: 9.1 TiB, 10000831348736 bytes, 19532873728 sectors
Disk model: WDC WD101EFBX-68
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: C4F9C925-1FEA-4655-A2D7-D84428C9198B

Device     Start         End     Sectors  Size Type
/dev/sdf1   4096 19532871680 19532867585  **9.1T** Solaris /usr & Apple ZFS
admin@truenas[~]$ sudo fdisk -l /dev/sdb
Disk /dev/sdb: 10.91 TiB, 12000138625024 bytes, 23437770752 sectors
Disk model: TOSHIBA HDWG21C 
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 5AEC1BCE-598F-4215-898B-C85B29BEBD23

Device     Start         End     Sectors  Size Type
/dev/sdb1   4096 23437768704 23437764609 **10.9T** Solaris /usr & Apple ZFS

Why is the WebUI handling it that way?

I’m asking because, if I attach the bigger 12 TB drive via terminal, I can still replace it against a 10 TB, but if it was done in the WebUI I can’t because of the bigger partition size?!

I hope you guys understand what I mean.


So that when you replace all the vdev members with larger disks the space will auto expand.

Surprised that zpool attach is not doing it.

Also surprised you do not have a “swap” partition.

IDK, it never created a swap for me on any drive, even tho I’ve it in active?!

Which version of scale?

OS Version: TrueNAS-SCALE-

I think there may be a “regression”’there due to removing swap in 24.04.1.

The swap partitions really should still be being made, but perhaps they are not.

I think starting in the swap partitions are not being made on new installs by default or by default on any new vdevs that are created. Upgrading an existing system to will remove the swap, but the swap partitions will still be there. After it is proven, and in a later version of Scale, the swap partitions will be removed altogether during an upgrade. At least that was my understanding of the path forward. Kris (I think) posted somewhere on the forum some detailed info on the what, why, when.

Truenas being an appliance is designed to mainly use the GUI for most operations. Using the CLI when a GUI counterpart is available can and sometimes does cause issues or presents different results. Or at least it has in the past. General recommendations are to use the GUI unless something specific cannot be performed with the GUI, then fall back to the CLI commands.

I have had no issues at all related to removal of swap partitions, and am glad they are being removed.