Re: FreeBSD guest online disk resize

I have a branch cooking that listens to the namespace resize and do the
size changes to geom. Later this week.

Warner

On Mon, Nov 17, 2025, 12:01 PM Alexandre Biancalana <biancalana@gmail.com>
wrote:

> Hello,
>
> I am using bhyve with several VMs where the VM disks (NVMe) are stored
> on an NFS server and exported to the hypervisor. Occasionally, I need
> to expand the disks due to space constraints. I perform this expansion
> by resizing the VM disk files using the truncate command.
>
> On Linux guests, the disk resize is immediately recognized, and the
> filesystem can be expanded online without issues.
>
> However, on FreeBSD guests, while the NVMe layer recognizes the disk
> resize (confirmed by the appearance of the asynchronous event message
> in dmesg):
>
> nvme2: async event occurred (type 0x2, info 0x00, page 0x04)
>
> and `nvmecontrol devlist` correctly shows the new disk size, there is a
> problem.
>
> The VM disk has no partition table and is formatted entirely with UFS
> and has a ufs label, hence geom_label is in use. Unfortunately, glabel
> list does not recognize the disk resize and still shows the old disk
> size.
>
> I have tried the following attempts to force recognition of the new
> size without success:
>
> Setting `sysctl kern.geom.debugflags=16`
>
> Resetting the NVMe controller with `nvmecontrol reset nvme2`
>
> Rescanning the disk with `camcontrol rescan nda2` and `camcontrol reprobe
> nda2`
>
> Ideally, I would like to perform a disk resize that FreeBSD recognizes
> without requiring a system reboot.
>
> Am I missing a step, or is there a recommended procedure to make
> geom_label recognize the resized disk size dynamically on FreeBSD
> guests?
>
>