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.\" $FreeBSD$
.Dd October 12, 2016
.Dt HV_VSS_DAEMON 8
.Os
.Sh NAME
.Nm hv_vss_daemon
.Nd Hyper-V Volume Shadow Copy Service Daemon
.Sh SYNOPSIS
.Nm
.Op Fl dn
.Sh DESCRIPTION
The
.Nm
daemon provides the ability to freeze and thaw the file system for
.Fx
guest partitions running on Hyper-V.
.Pp
Hyper-V allows administrators to backup or restore the 
.Fx
guest partition.
Administrators can
use Windows Powershell scripts to backup or restore the
.Fx
VM.
.Pp
The
.Nm
accepts file system freeze and thaw requests from the
.Xr hv_utils 4
driver and performs the actual file-system operation.
.Pp
The file system freeze and thaw functionality is
useful when the Hyper-V host wants to do live backup of
.Fx
guest. Hyper-V host sends file system freezing request to
.Nm
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
.Fx
VM through that snapshot.
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl d
Run as regular process instead of a daemon for debugging purpose.
.It Fl n
Generate debugging output.
.El
.Sh SEE ALSO
.Xr hv_vmbus 4 ,
.Xr hv_utils 4 ,
.Xr hv_netvsc 4 ,
.Xr hv_storvsc 4 ,
.Xr hv_kvp 4
.Sh HISTORY
The daemon was introduced in October 2016 and developed by Microsoft Corp.
.Sh AUTHORS
.An -nosplit
.Fx
support for
.Nm
was first added by
.An Microsoft BSD Integration Services Team Aq Mt bsdic@microsoft.com .