---
name: "hv_vss_daemon"
section: "8"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/hv_vss_daemon"
---

# hv\_vss\_daemon(8)

Hyper-V Volume Shadow Copy Service Daemon

## NAME

**hv\_vss\_daemon** – Hyper-V Volume Shadow Copy Service Daemon

## SYNOPSIS

**hv\_vss\_daemon** \[**-dn**\]

## DESCRIPTION

The **hv\_vss\_daemon** daemon provides the ability to freeze and thaw the file system for FreeBSD guest partitions running on Hyper-V.

Hyper-V allows administrators to backup or restore the  FreeBSD guest partition. Administrators can use Windows Powershell scripts to backup or restore the FreeBSD VM.

The **hv\_vss\_daemon** accepts file system freeze and thaw requests from the [hv\_utils(4)](/hv_utils/4.md) driver and performs the actual file-system operation.

The file system freeze and thaw functionality is useful when the Hyper-V host wants to do live backup of FreeBSD guest. Hyper-V host sends file system freezing request to **hv\_vss\_daemon** which conducts the real operation. After successfully freezing file system, Hyper-V host takes a snapshot of the VM. In the future, Hyper-V host can restore the FreeBSD VM through that snapshot.

The options are as follows:

- **-d**

  Run as regular process instead of a daemon for debugging purpose.

- **-n**

  Generate debugging output.

## SEE ALSO

[hv\_vmbus(4)](/hv_vmbus/4.md), [hv\_utils(4)](/hv_utils/4.md), [hv\_netvsc(4)](/hv_netvsc/4.md), [hv\_storvsc(4)](/hv_storvsc/4.md), [hv\_kvp(4)](/hv_kvp/4.md)

## HISTORY

The daemon was introduced in October 2016 and developed by Microsoft Corp.

## AUTHORS

FreeBSD support for **hv\_vss\_daemon** was first added by Microsoft BSD Integration Services Team ⟨*bsdic@microsoft.com*⟩.