最後更新: 2019-10-08

 

介紹

 

安 agent 後有的好處(功能)

支援 virsh 的 shutdown / reboot

In virsh, users can select shutdown/reboot method via "--mode agent"

ie.

virsh reboot --mode agent $DOMAIN

virsh shutdown --mode agent $DOMAIN

freeze fs

在建立 snapshots 可以 freeze filesystems, 令獲得的 snapshot 完整

ie.

virsh snapshot-create --quiesce $DOMAIN

virsh snapshot-create-as --quiesce $DOMAIN

virsh blockcommit

# The contents of snap2 are moved into snap1, resulting in:

# base ← snap1 ← active, snap2 is no longer valid and can be deleted

i.e.

virsh blockcommit $dom $disk -base snap1 -top snap2 -wait -verbose

 

---

QEMU Guest Agent

 

 

[Step1] Host

QEMU exposes GA via virtio serial port

<devices>
  ...
  <channel type='unix'>
   <source mode='bind'/>
   <target type='virtio' name='org.qemu.guest_agent.0'/>
  </channel>
</devices>

Save 後

    <channel type='unix'>
      <target type='virtio' name='org.qemu.guest_agent.0'/>
      <address type='virtio-serial' controller='0' bus='0' port='1'/>
    </channel>

Checking: 當 Guest Start 後

Hypervisor 會有

ls -l /var/lib/libvirt/qemu/channel/target/domain-*/org.qemu.guest_agent.0

srwxrwxr-x 1 libvirt-qemu kvm 0 May 26 18:06
 /var/lib/libvirt/qemu/channel/target/domain-ID-VM_NAME/org.qemu.guest_agent.0
...

Guest 會有

ls -l /dev/virtio-ports/org.qemu.guest_agent.0

lrwxrwxrwx 1 root root 11 May 26 10:06 /dev/virtio-ports/org.qemu.guest_agent.0 -> ../vport3p1

/etc/init.d/qemu-guest-agent

# default transport
TRANSPORT=virtio-serial:/dev/virtio-ports/org.qemu.guest_agent.0

P.S. virtio-serial

A transport mechanism is needed for communication between the host userspace and guest userspace

It has two parts:(Guest)
(a) device emulation in qemu that presents a virtio-pci device to the guest and
(b) a guest driver that presents a char device interface to userspace applications.

[Step2] Guest

Debian/Ubuntu

apt-get install qemu-guest-agent

Centos

yum install qemu-guest-agent

Notes

The QEMU guest agent package ( qemu-guest-agent ) is installed by default in Red Hat Enterprise Linux 7

Start & Enable Service

systemctl enable qemu-guest-agent --now

[Step3] Test qemu-guest-agent

domtime seafile

失敗

error: argument unsupported: QEMU guest agent is not configured

OR

error: Guest agent is not responding: Guest agent not available for now

成功

Time: 1552741916

P.S.

date

Friday, May 26, 2023 PM06:20:02 HKT

virsh domtime --pretty u22

# 這裡的時間係用 Guest 的時區

Time: 2023-05-26 10:20:02

 

---

Usage

 

domtime seafile

Time: 1514292860

沒有安 agent 時

error: Guest agent is not responding: QEMU guest agent is not connected

domfsinfo seafile

Mountpoint                           Name     Type     Target
-------------------------------------------------------------------
/                                    dm-0     xfs      vda
/boot                                vda1     xfs      vda

set-user-password

set-user-password domain user password

fsfreeze

virsh domfsfreeze guestname 

Freeze domain's mounted filesystems.

此時 VM 沒有了 Disk 的 R/W 能力

virsh domfsthaw guestname

Thaw mounted filesystems within a running domain, which have been frozen by domfsfreeze command.

用處: Backup running VM

virsh domfsfreeze vmname

qemu-img create -f qcow2 -b qcow2image.vm qcow2.snap

OR

cp qcow2.snap backup.img

 

---

Window 's GA

 

好處

# 分別: some guests ignore ACPI shutdown event

virsh shutdown --mode=agent GUEST

# 分別: snapshot without having to perform a fsck

virsh snapshot-create --quiesce GUEST

# 分別: using the guest operating system's power management functions.

virsh dompmsuspend GUEST

Intro:

http://www.linux-kvm.org/page/WindowsGuestDrivers

Binary Drivers:

https://fedorapeople.org/groups/virt/virtio-win/direct-downloads/stable-virtio/virtio-win.iso

獲得

/mnt/tmp
├── amd64
│   ├── 2k8
│   ├── ...
│   └── w8
├── ARM64
│   └── w10
├── Balloon
│   ├── 2k12
│   ├── ...
│   └── xp
├── guest-agent
│   ├── qemu-ga-i386.msi
│   └── qemu-ga-x86_64.msi
...

# Guest 的 XML

# Note that the source socket name must be unique in the host, 非切要
<channel type='unix'>
    <source mode='bind' path='/var/lib/libvirt/qemu/win7x86.agent'/>
    <target type='virtio' name='org.qemu.guest_agent.0'/>
</channel>

# Guest 開機後

# 入 CD 安 virtio-serial driver

virsh attach-disk guest /home/iso/virtio-win.iso hdc --type cdrom

在 Control Panel > Hardware and Sound > Device manager > 安 vioserial

Install guest-agent/qemu-ga-i386.msi

Checking

# Power Shell

Get-Service QEMU-GA

Status   Name               DisplayName
------   ----               -----------
Running  QEMU-GA            QEMU Guest Agent

 

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