Question about bhyve disk images

Paul Vixie paul at
Sun Feb 7 01:14:49 UTC 2016

Rainer Duffner wrote:
> Hi,
> is it possible to increase the size of these images (after creation,
> and while the guest OS is running)?

there is no driver-layer signal to tell the guest OS that a drive just 
got larger, so the guest OS would have to poll, or be told to sense.

with freebsd 10 as the guest OS, i've been able to use growfs to make it 
expand the the hog (last) file system on a virtual drive. but i did it 
by shutting down the guest, growing the zvol, booting the guest, and 
running growfs inside the guest. i havn't tried avoiding the shutdown 
and reboot.

> How large can they be?

if you're using virtio_blk there should be no limit.

> I may have a use-case where I would need to have images in the size
> oftens of terabytes.
> Or is there a way to delegate a ZFS (or a pool) to a bhyve guest?

this is sort of what zvol does, noting, the zfs code runs in the parent.

P Vixie

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