Simple virsh commands.

Simple virsh commands.

# /bin/systemctl restart  libvirtd.service
# /bin/systemctl enable  libvirtd.service

Note:
How to turn on the debug logs for libvirtd.
1)open /etc/libvirt/libvirtd.conf in your favourite editor.
2)find & replace, or set these variables:
log_level = 1
log_filters="3:remote 4:event 3:json 3:rpc" | log_filters="1:qemu_monitor_json"
log_outputs="1:file:/var/log/libvirt/libvirtd.log"
3)save and exit the configure file.
4)restart libvirtd service.
# systemctl restart libvirtd.service

= I. Domain Management =

- define (but don't start) a domain from an XML file
# virsh define $domain_name.xml
Domain domain_name defined from domain_name.xml
- start a (previously defined) inactive domain
# virsh start $domain_name
Domain domain_name started

- create a domain from an XML file
# virsh create domain_name.xml 
Domain domain_name created from domain_name.xml
virsh:suspend/resume = HMP/QMP:stop/cont

# virsh suspend 1
Domain 1 suspended
# virsh list --all
 Id    Name                           State
----------------------------------------------------
 1     domain_name                    paused
# virsh resume 1
Domain 1 resumed
# virsh list --all
 Id    Name                           State
----------------------------------------------------
 1     domain_name                    running

# virsh reboot $domain_name
Domain $domain_name is being rebooted

# virsh qemu-monitor-command $domain_name --hmp info qtree

# virsh attach-device $domain_name $device_name.xml

- destroy(stop)/undefine a domain
# virsh destroy $domain_name
Domain domain_name destroyed
# virsh undefine $domain_name
Domain domain_name has been undefined
   
{ "execute": "guest-suspend-ram"}
{ "execute": "guest-suspend-disk"}
#virsh dompmsuspend $domain-name mem
#virsh dompmwakeup $domain-name 
#virsh dompmsuspend $domain-name  disk

- migrate domain to another host
# virsh migrate --live $domain_name qemu+ssh://$dst_ip/system
    migrate-setmaxdowntime         set maximum tolerable downtime
    migrate-compcache              get/set compression cache size
    migrate-setspeed               Set the maximum migration bandwidth
    migrate-getspeed               Get the maximum migration bandwidth

- vnc display
# virsh vncdisplay $domain_name
127.0.0.1:0
connetion ]# vncviewer 127.0.0.1:0  # remote-viewer vnc://127.0.0.1:5900

- refer to
 virsh help
# virsh --help
# virsh $command --help

- Send keycodes to the guest
# virsh send-key $domain_name $keycode_string
$keycode_string: alt-sysrq-h/alt-sysrq-t/alt-sysrq-m/alt-sysrq-c
e.g.:# virsh send-key sluo_kvm_testing_example KEY_LEFTALT KEY_SYSRQ KEY_H

- dump the core of a domain to a file for analysis, dumpxml domain information in XML.
# virsh dump $domain_name $file_name
# virsh dumpxml $domain_name

- attach/detach disk device
# virsh attach-disk $domain_name /home/my-data-disk.raw vda
Disk attached successfully
# virsh dumpxml $domain_name
......
    </disk>
    <disk type='file' device='disk'>
      <driver name='qemu' type='raw'/>
      <source file='/home/my-data-disk.raw'/>
      <target dev='vda' bus='virtio'/>
      <alias name='virtio-disk0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </disk>
    </controller>
    <controller type='scsi' index='0'>
      <alias name='scsi0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
    </controller>
......
# virsh detach-disk sluo_kvm_testing_example vda
Disk detached successfully

- QEMU Monitor Command
# virsh qemu-monitor-command $domain_name --hmp 'info qtree'
# virsh qemu-monitor-command rhel7.1 --pretty '{"execute":"xxxxxx"}'
e.g.
# virsh qemu-monitor-command rhel7.1 --pretty '{"execute":"query-iothreads"}'
{
    "return": [
    ],
    "id": "libvirt-11"
}

- QEMU Guest Agent Command
# virsh qemu-agent-command $domain_name --async --cmd 'xxx'

# virsh qemu-agent-command test '{"execute":"guest-info"}'

= II. Domain Monitoring (help keyword 'monitor') =
- list domains
# virsh list
 Id    Name                           State
----------------------------------------------------
 1     domain_name                    running

- list inactive & active domains
# virsh list --all

- domain state
# virsh domstate $domain_name
running

- get memory statistics for a domain
# virsh dommemstat $domain_name
actual 2097152
rss 1030884

- domain information
# virsh dominfo $domain_name
Id:             12
Name:           sluo_kvm_testing_example
UUID:           d1a23b70-ab58-47a7-9ad7-0de528202542
OS Type:        hvm
State:          running
CPU(s):         2
CPU time:       76.3s
Max memory:     2097152 KiB
Used memory:    2097152 KiB
Persistent:     yes
Autostart:      disable
Managed save:   no
Security model: selinux
Security DOI:   0
Security label: system_u:system_r:svirt_t:s0:c179,c990 (permissive)

- list all domain virtual interfaces
# virsh domiflist $domain_name
Interface  Type       Source     Model       MAC
-------------------------------------------------------
vnet0      network    default    virtio-net-pci 0c:01:38:b6:40:24

- get link state of a virtual interface
# virsh domif-getlink $domain_name --interface 0c:01:38:b6:40:24
0c:01:38:b6:40:24 default

- get network interface stats for a domain
# virsh  domifstat $domain_name vnet0
vnet0 rx_bytes 45472
vnet0 rx_packets 870
vnet0 rx_errs 0
vnet0 rx_drop 0
vnet0 tx_bytes 0
vnet0 tx_packets 0
vnet0 tx_errs 0
vnet0 tx_drop 0

- domain control interface state
# virsh domcontrol $domain_name
ok

- list all domain blocks
# virsh domblklist $domain_name
Target     Source
------------------------------------------------
hda        /home/RHEL-7.0-20140507.0-Server-x86_64.qcow2

- domain block device size information
# virsh domblkinfo $domain_name
Capacity:       10737418240
Allocation:     6684946432
Physical:       6684946432

- show errors on block devices
# virsh domblkerror $domain_name
No errors found

Install guest via network using virsh XML.
<os>
  <type arch='x86_64' machine='pc'>hvm</type>
  <kernel>/var/lib/libvirt/boot/vmlinuz</kernel>
  <initrd>/var/lib/libvirt/boot/initrd.img</initrd>
  <cmdline>method=http://download.englab.nay.redhat.com/pub/rhel/rel-eng/latest-RHEL-7/compose/Server/x86_64/os
  ks=http://fileshare.englab.nay.redhat.com/pub/section3/run/http-ks/ks-rhel7-x86_64.cfg
  </cmdline>
  <boot dev='hd'/>
</os>