If you haven't enabled autoexpand on the pool before you started to replace all disks of the related virtual device with higher capacity disks, you have to issue command zpool online -e [device] either via WebGUI (Disks > ZFS > Tools > Bring a device online) or command line.
Reference: FreeBSD Manual Pages - zpool > online
Code: Select all
zpool online [-e] pool device ...
Brings the specified physical device online.
This command is not applicable to spares or cache devices.
-e Expand the device to use all available space. If the device
is part of a mirror or raidz then all devices must be
expanded before the new space will become available to the
after you successfully expanded the vdev you should synchronize ZFS information with the WebGUI (Disks > ZFS > Configuration > Synchronize)
1) XigmaNAS 184.108.40.206 amd64-embedded on a Dell T20 running in a VM on ESXi 6.7U2, 22GB out of 32GB ECC RAM, LSI 9300-8i IT mode in passthrough mode. Pool 1: 2x HGST 10TB, mirrored, SLOG: Samsung 850 Pro, L2ARC: Samsung 850 Pro, Pool 2: 1x Samsung 860 EVO 1TB , services: Samba AD, CIFS/SMB, ftp, ctld, rsync, syncthing, zfs snapshots.
2) XigmaNAS 220.127.116.11 amd64-embedded on a Dell T20 running in a VM on ESXi 6.7U2, 8GB out of 32GB ECC RAM, IBM M1215 crossflashed, IT mode, passthrough mode, 2x HGST 10TB , services: rsync.