在前邊的博客中，我們大致了解了virsh這個工具對kvm虛擬機的一些操作，回顧請參考https://www.cnblogs.com/qiuhom-1874/tag/virsh/；今天我們來了解下kvm的磁盤管理工具qemu-img常用命令的用法；
1、qemu-img的幫助資訊
[root@node1 ~]# qemu-img -h
qemu-img version 1.5.3, Copyright (c) 2004-2008 Fabrice Bellard
usage: qemu-img command [command options]
QEMU disk image utility
Command syntax:
check [-q] [-f fmt] [--output=ofmt] [-r [leaks | all]] [-T src_cache] filename
create [-q] [-f fmt] [-o options] filename [size]
commit [-q] [-f fmt] [-t cache] filename
compare [-f fmt] [-F fmt] [-T src_cache] [-p] [-q] [-s] filename1 filename2
convert [-c] [-p] [-q] [-n] [-f fmt] [-t cache] [-T src_cache] [-O output_fmt] [-o options] [-s snapshot_name] [-S sparse_size] filename [filename2 [...]] output_filename
info [-f fmt] [--output=ofmt] [--backing-chain] filename
map [-f fmt] [--output=ofmt] filename
snapshot [-q] [-l | -a snapshot | -c snapshot | -d snapshot] filename
rebase [-q] [-f fmt] [-t cache] [-T src_cache] [-p] [-u] -b backing_file [-F backing_fmt] filename
resize [-q] filename [+ | -]size
amend [-q] [-f fmt] [-t cache] -o options filename
Command parameters:
'filename' is a disk image filename
'fmt' is the disk image format. It is guessed automatically in most cases
'cache' is the cache mode used to write the output disk image, the valid
options are: 'none', 'writeback' (default, except for convert), 'writethrough',
'directsync' and 'unsafe' (default for convert)
'src_cache' is the cache mode used to read input disk images, the valid
options are the same as for the 'cache' option
'size' is the disk image size in bytes. Optional suffixes
'k' or 'K' (kilobyte, 1024), 'M' (megabyte, 1024k), 'G' (gigabyte, 1024M),
'T' (terabyte, 1024G), 'P' (petabyte, 1024T) and 'E' (exabyte, 1024P) are
supported. 'b' is ignored.
'output_filename' is the destination disk image filename
'output_fmt' is the destination format
'options' is a comma separated list of format specific options in a
name=value format. Use -o ? for an overview of the options supported by the
used format
'-c' indicates that target image must be compressed (qcow format only)
'-u' enables unsafe rebasing. It is assumed that old and new backing file
match exactly. The image doesn't need a working backing file before
rebasing in this case (useful for renaming the backing file)
'-h' with or without a command shows this help and lists the supported formats
'-p' show progress of command (only certain commands)
'-q' use Quiet mode - do not print any output (except errors)
'-S' indicates the consecutive number of bytes (defaults to 4k) that must
contain only zeros for qemu-img to create a sparse image during
conversion. If the number of bytes is 0, the source will not be scanned for
unallocated or zero sectors, and the destination image will always be
fully allocated
'--output' takes the format in which the output must be done (human or json)
'-n' skips the target volume creation (useful if the volume is created
prior to running qemu-img)
Parameters to check subcommand:
'-r' tries to repair any inconsistencies that are found during the check.
'-r leaks' repairs only cluster leaks, whereas '-r all' fixes all
kinds of errors, with a higher risk of choosing the wrong fix or
hiding corruption that has already occurred.
Parameters to snapshot subcommand:
'snapshot' is the name of the snapshot to create, apply or delete
'-a' applies a snapshot (revert disk to saved state)
'-c' creates a snapshot
'-d' deletes a snapshot
'-l' lists all snapshots in the given image
Parameters to compare subcommand:
'-f' first image format
'-F' second image format
'-s' run in Strict mode - fail on different image size or sector allocation
Supported formats: vvfat vpc vmdk vhdx vdi ssh sheepdog rbd raw host_cdrom host_floppy host_device file qed qcow2 qcow parallels nbd iscsi gluster dmg tftp ftps ftp https http cloop bochs blkverify blkdebug
[root@node1 ~]#
提示：從上面的幫助資訊可以看到qemu-img這個命令分了check、create、commit、compare、convert、info、map、snapshot、rebase、resize、amend這些子命令，每個子命令都有特有的功能和語法以及選項；
qemu-img create：用于創建磁盤檔案使用的命令,語法格式：qemu-img create [-q] [-f fmt] [-o options] filename [size];其中-f用于指定磁盤的格式，常用的格式有，raw,qcow,qcow2；如果要查看create子命令還有那些選項可用，可以是使用-o ？來指定,如下示例；
示例：查看create子命令的選項說明，可以使用qemu-img create -f qcow2 -o ? /kvm/images/test.img
[root@node1 ~]# qemu-img create -f qcow2 -o ? /kvm/images/test.img Supported options: size Virtual disk size compat Compatibility level (0.10 or 1.1) backing_file File name of a base image backing_fmt Image format of the base image encryption Encrypt the image cluster_size qcow2 cluster size preallocation Preallocation mode (allowed values: off, metadata, falloc, full) lazy_refcounts Postpone refcount updates [root@node1 ~]#
提示：以上示例表示要創建/kvm/images/test.img磁盤檔案格式為qcow2它有哪些選項；這里需要說明一點在linux系統上檔案的后綴只是起給人看的作用，方便人區分它，系統它不以后綴來確定它的格式；從上面的幫助資訊可以看到create子命令的選項有size，該選項用于指定創建磁盤檔案的大小；compat選項用于指定兼容性；backing_file用于指定備份檔案名稱；backing_fmt用于指定備份檔案的格式；encryption用于指定是否加密，true表示加密false表示不加密，默認不指定是false；cluster_size指定磁盤的簇大小；preallocation用于指定磁盤預分配策略，其中off表示不預分配，metadata表示只預分配元資料大小，falloc表示隨檔案的增加而分配，full表示立即分配所有磁盤空間；默認是指不預分配磁盤空間大小；
示例：創建一個2G的磁盤，分別用不同的預分配策略機制
[root@node1 ~]# qemu-img create -f qcow2 -o preallocation=off,size=2G /kvm/images/a1.img
Formatting '/kvm/images/a1.img', fmt=qcow2 size=2147483648 encryption=off cluster_size=65536 preallocation='off' lazy_refcounts=off
[root@node1 ~]# ll -h /kvm/images/a1.img
-rw-r--r-- 1 root root 193K 8月 18 22:17 /kvm/images/a1.img
[root@node1 ~]# qemu-img info /kvm/images/a1.img
image: /kvm/images/a1.img
file format: qcow2
virtual size: 2.0G (2147483648 bytes)
disk size: 196K
cluster_size: 65536
Format specific information:
compat: 1.1
lazy refcounts: false
[root@node1 ~]# qemu-img create -f qcow2 -o preallocation=metadata,size=2G /kvm/images/a2.img
Formatting '/kvm/images/a2.img', fmt=qcow2 size=2147483648 encryption=off cluster_size=65536 preallocation='metadata' lazy_refcounts=off
[root@node1 ~]# ll -h /kvm/images/a2.img
-rw-r--r-- 1 root root 2.1G 8月 18 22:18 /kvm/images/a2.img
[root@node1 ~]# qemu-img info /kvm/images/a2.img
image: /kvm/images/a2.img
file format: qcow2
virtual size: 2.0G (2147483648 bytes)
disk size: 708K
cluster_size: 65536
Format specific information:
compat: 1.1
lazy refcounts: false
[root@node1 ~]# qemu-img create -f qcow2 -o preallocation=falloc,size=2G /kvm/images/a3.img
Formatting '/kvm/images/a3.img', fmt=qcow2 size=2147483648 encryption=off cluster_size=65536 preallocation='falloc' lazy_refcounts=off
[root@node1 ~]# ll -h /kvm/images/a3.img
-rw-r--r-- 1 root root 2.1G 8月 18 22:19 /kvm/images/a3.img
[root@node1 ~]# qemu-img info /kvm/images/a3.img
image: /kvm/images/a3.img
file format: qcow2
virtual size: 2.0G (2147483648 bytes)
disk size: 2.0G
cluster_size: 65536
Format specific information:
compat: 1.1
lazy refcounts: false
[root@node1 ~]# qemu-img create -f qcow2 -o preallocation=full,size=2G /kvm/images/a4.img
Formatting '/kvm/images/a4.img', fmt=qcow2 size=2147483648 encryption=off cluster_size=65536 preallocation='full' lazy_refcounts=off
[root@node1 ~]# ll -h /kvm/images/a4.img
-rw-r--r-- 1 root root 2.1G 8月 18 22:21 /kvm/images/a4.img
[root@node1 ~]# qemu-img info /kvm/images/a4.img
image: /kvm/images/a4.img
file format: qcow2
virtual size: 2.0G (2147483648 bytes)
disk size: 2.0G
cluster_size: 65536
Format specific information:
compat: 1.1
lazy refcounts: false
[root@node1 ~]#
提示：從上面的示例可以看到除了off指定創建的磁盤，我們看到的大小是一個很小的大小，其他模式在檔案系統上表現形式都是我們指定大小的空間；從qemu-img info 命令來看，off和metadata disk size是很小的空間，虛擬空間是我們指定的大小；后者falloc和full disk大小和virtual size大小都是我們指定的大小；在檔案系統上看到的磁盤檔案之所以要大于我們指定的空間，是因為在檔案系統上它作為一個檔案形式存在，它也有元素資料資訊的；
qemu-img info ：用于查看指定磁盤檔案的詳細資訊；用法格式：qemu-img info [-f fmt] [--output=ofmt] [--backing-chain] filename
[root@node1 ~]# qemu-img info /kvm/images/centos7.qcow2
image: /kvm/images/centos7.qcow2
file format: qcow2
virtual size: 10G (10737418240 bytes)
disk size: 196K
cluster_size: 65536
Format specific information:
compat: 1.1
lazy refcounts: false
[root@node1 ~]# qemu-img info /kvm/images/win7.qcow2
image: /kvm/images/win7.qcow2
file format: qcow2
virtual size: 50G (53687091200 bytes)
disk size: 8.5G
cluster_size: 65536
Format specific information:
compat: 1.1
lazy refcounts: false
[root@node1 ~]#
qemu-img check：對指定磁盤檔案做檢查;用法格式：qemu-img check [-q] [-f fmt] [--output=ofmt] [-r [leaks | all]] [-T src_cache] filename
[root@node1 ~]# qemu-img check /kvm/images/win7.qcow2 No errors were found on the image. 138808/819200 = 16.94% allocated, 27.22% fragmented, 0.00% compressed clusters Image end offset: 9098887168 [root@node1 ~]# qemu-img check /kvm/images/centos7.qcow2 No errors were found on the image. Image end offset: 262144 [root@node1 ~]#
qemu-img snapshot：對指定磁盤檔案做快照相關操作；語法格式：qemu-img snapshot [-q] [-l | -a snapshot | -c snapshot | -d snapshot] filename
-c：表示創建快照
[root@node1 ~]# qemu-img snapshot -c snapshot_centos7_1 /kvm/images/centos7.qcow2
-l：查看指定磁盤檔案的快照串列
[root@node1 ~]# qemu-img snapshot -l /kvm/images/centos7.qcow2 Snapshot list: ID TAG VM SIZE DATE VM CLOCK 1 snapshot_centos7_1 0 2017-03-29 01:16:08 00:00:00.000 [root@node1 ~]#
-a：應用快照，將磁盤恢復到做快照那一刻；
[root@node1 ~]# qemu-img snapshot -a snapshot_centos7_1 /kvm/images/centos7.qcow2 [root@node1 ~]#
-d：洗掉快照
[root@node1 ~]# qemu-img snapshot -l /kvm/images/centos7.qcow2 Snapshot list: ID TAG VM SIZE DATE VM CLOCK 1 snapshot_centos7_1 0 2017-03-29 01:16:08 00:00:00.000 [root@node1 ~]# qemu-img snapshot -d snapshot_centos7_1 /kvm/images/centos7.qcow2 [root@node1 ~]# qemu-img snapshot -l /kvm/images/centos7.qcow2 [root@node1 ~]#
qemu-img convert：鏡像格式轉換，語法格式：qemu-img convert [-c] [-p] [-q] [-n] [-f fmt] [-t cache] [-T src_cache] [-O output_fmt] [-o options] [-s snapshot_name] [-S sparse_size] filename [filename2 [...]] output_filename；-c表示壓縮輸出檔案，但只有qcow2和qcow格式的鏡像檔案才支持壓縮，而且這種壓縮是只讀的，如果壓縮的扇區被重寫，則會被重寫為未壓縮的資料，-p用于顯示轉換進度；-o用于指定輸出檔案的選項，比如是否加密呀，大小，等等，，
示例1：不加輸出格式直接轉換qcow2格式的磁盤檔案
[root@node1 ~]# qemu-img create -f qcow2 /kvm/images/test1.img 1G
Formatting '/kvm/images/test1.img', fmt=qcow2 size=1073741824 encryption=off cluster_size=65536 lazy_refcounts=off
[root@node1 ~]# qemu-img info /kvm/images/test1.img
image: /kvm/images/test1.img
file format: qcow2
virtual size: 1.0G (1073741824 bytes)
disk size: 196K
cluster_size: 65536
Format specific information:
compat: 1.1
lazy refcounts: false
[root@node1 ~]# qemu-img convert /kvm/images/test1.img test1-1.img
[root@node1 ~]# qemu-img info test1-1.img
image: test1-1.img
file format: raw
virtual size: 1.0G (1073741824 bytes)
disk size: 0
[root@node1 ~]#
提示：qemu-img convert輸入的檔案格式它會自動識別，輸出格式如果不指定它默認轉換為raw格式；
示例2：就vmdk格式的檔案轉換成qcow2格式的磁盤檔案
[root@node1 ~]# cd /kvm/images/
[root@node1 images]# ls
centos7.qcow2 test1.img
[root@node1 images]# rz
rz waiting to receive.
zmodem trl+C ?
100% 512 KB 512 KB/s 00:00:01 0 Errors01-s001.vmdk...
[root@node1 images]# ls
CentOS-6.9-x86_64-000001-s001.vmdk centos7.qcow2 test1.img
[root@node1 images]# qemu-img info CentOS-6.9-x86_64-000001-s001.vmdk
image: CentOS-6.9-x86_64-000001-s001.vmdk
file format: vmdk
virtual size: 4.0G (4261412864 bytes)
disk size: 512K
cluster_size: 65536
Format specific information:
cid: 4294967295
parent cid: 4294967295
create type: monolithicSparse
extents:
[0]:
virtual size: 4261412864
filename: CentOS-6.9-x86_64-000001-s001.vmdk
cluster size: 65536
format:
[root@node1 images]# qemu-img convert ./CentOS-6.9-x86_64-000001-s001.vmdk -O qcow2 ./centos6.qcow2
[root@node1 images]# ll
總用量 1244560
-rw-r--r-- 1 root root 524288 4月 19 2020 CentOS-6.9-x86_64-000001-s001.vmdk
-rw-r--r-- 1 root root 197120 3月 29 01:33 centos6.qcow2
-rw-r--r-- 1 qemu qemu 1273561600 3月 29 01:32 centos7.qcow2
-rw-r--r-- 1 root root 197120 3月 29 01:24 test1.img
[root@node1 images]# qemu-img info ./centos6.qcow2
image: ./centos6.qcow2
file format: qcow2
virtual size: 4.0G (4261412864 bytes)
disk size: 196K
cluster_size: 65536
Format specific information:
compat: 1.1
lazy refcounts: false
[root@node1 images]#
提示：我們可以根據把不同格式的磁盤檔案相互轉換，從而實作把虛擬機從一個平臺遷移到另一個平臺；
qemu-img resize：動態增刪磁盤的大小；語法格式：qemu-img resize [-q] filename [+ | -]size；
[root@node1 images]# ll -h
總用量 1.2G
-rw-r--r-- 1 root root 512K 4月 19 2020 CentOS-6.9-x86_64-000001-s001.vmdk
-rw-r--r-- 1 root root 193K 3月 29 01:33 centos6.qcow2
-rw-r--r-- 1 qemu qemu 1.2G 3月 29 02:03 centos7.qcow2
-rw-r--r-- 1 root root 193K 3月 29 01:24 test1.img
[root@node1 images]# qemu-img info test1.img
image: test1.img
file format: qcow2
virtual size: 1.0G (1073741824 bytes)
disk size: 196K
cluster_size: 65536
Format specific information:
compat: 1.1
lazy refcounts: false
[root@node1 images]# qemu-img resize test1.img +1G
Image resized.
[root@node1 images]# qemu-img info test1.img
image: test1.img
file format: qcow2
virtual size: 2.0G (2147483648 bytes)
disk size: 260K
cluster_size: 65536
Format specific information:
compat: 1.1
lazy refcounts: false
[root@node1 images]# ll -h
總用量 1.2G
-rw-r--r-- 1 root root 512K 4月 19 2020 CentOS-6.9-x86_64-000001-s001.vmdk
-rw-r--r-- 1 root root 193K 3月 29 01:33 centos6.qcow2
-rw-r--r-- 1 qemu qemu 1.2G 3月 29 02:04 centos7.qcow2
-rw-r--r-- 1 root root 257K 3月 29 02:04 test1.img
[root@node1 images]#
提示：動態縮減空間必須保證磁盤空間大于里面存盤的資料空間，在做刪減操作有必要先備份一免磁盤損壞導致資料丟失；
[root@node1 images]# qemu-img info test1.img
image: test1.img
file format: qcow2
virtual size: 2.0G (2147483648 bytes)
disk size: 200K
cluster_size: 65536
Format specific information:
compat: 1.1
lazy refcounts: false
[root@node1 images]# qemu-img resize test1.img -1G
qemu-img: qcow2 doesn't support shrinking images yet
qemu-img: This image does not support resize
[root@node1 images]#
提示：這里還需要注意一點，qcow2的格式磁盤不支持刪減操作；
2、示例：動態將創建好的磁盤插入現運行的虛擬機上；
新建磁盤
[root@node1 ~]# qemu-img create -f qcow2 -o preallocation=metadata,size=2G /kvm/images/c1.img
Formatting '/kvm/images/c1.img', fmt=qcow2 size=2147483648 encryption=off cluster_size=65536 preallocation='metadata' lazy_refcounts=off
[root@node1 ~]# qemu-img info /kvm/images/c1.img
image: /kvm/images/c1.img
file format: qcow2
virtual size: 2.0G (2147483648 bytes)
disk size: 708K
cluster_size: 65536
Format specific information:
compat: 1.1
lazy refcounts: false
[root@node1 ~]# ll -h /kvm/images/c1.img
-rw-r--r-- 1 root root 2.1G 3月 29 02:18 /kvm/images/c1.img
[root@node1 ~]#
把磁盤附加到現運行的虛擬機上
[root@node1 ~]# virsh list --all
Id 名稱 狀態
----------------------------------------------------
2 centos7 running
[root@node1 ~]# virsh domblklist centos7
目標 源
------------------------------------------------
vda /kvm/images/centos7.qcow2
hda -
[root@node1 ~]# virsh help attach-disk
NAME
attach-disk - 附加磁盤設備
SYNOPSIS
attach-disk <domain> <source> <target> [--targetbus <string>] [--driver <string>] [--subdriver <string>] [--iothread <string>] [--cache <string>] [--io <string>] [--type <string>] [--mode <string>] [--sourcetype <string>] [--serial <string>] [--wwn <string>] [--rawio] [--address <string>] [--multifunction] [--print-xml] [--persistent] [--config] [--live] [--current]
DESCRIPTION
附加新磁盤設備.
OPTIONS
[--domain] <string> domain name, id or uuid
[--source] <string> 磁盤設備源
[--target] <string> 磁盤設備目標
--targetbus <string> target bus of disk device
--driver <string> 磁盤設備驅動
--subdriver <string> 磁盤設備副驅動
--iothread <string> IOThread to be used by supported device
--cache <string> 磁盤設備的快取模式
--io <string> io policy of disk device
--type <string> 目標設備型別
--mode <string> 設備讀寫模式
--sourcetype <string> 源型別 (block|file)
--serial <string> 磁盤設備序列號
--wwn <string> 磁盤設備的 wwn
--rawio 需要 rawio 容量
--address <string> 磁盤設備地址
--multifunction 在指定地址中使用多功能 pci
--print-xml 輸出 XML 檔案而不是附加該磁盤
--persistent 讓實時更改持久
--config 影響下一次引導
--live 影響運行的域
--current 影響當前域
[root@node1 ~]# virsh attach-disk centos7 /kvm/images/c1.img hda
錯誤：附加磁盤失敗
錯誤：XML 錯誤：磁盤源 'hda' 和 '<null>' 有重復的目標 '/kvm/images/c1.img'
[root@node1 ~]# virsh attach-disk centos7 /kvm/images/c1.img hdb
錯誤：附加磁盤失敗
錯誤：不支持的操作：無法熱插拔磁盤總線 'ide'，
[root@node1 ~]# virsh attach-disk centos7 /kvm/images/c1.img vdb
成功附加磁盤
[root@node1 ~]# virsh domblklist centos7
目標 源
------------------------------------------------
vda /kvm/images/centos7.qcow2
vdb /kvm/images/c1.img
hda -
[root@node1 ~]#
提示：hd型別的磁盤上ide介面，ide介面型別的磁盤上不支持熱插拔的，所以我們要給它識別成支持熱插拔的磁盤型別，比如vd型別（virtual disk虛擬磁盤）
驗證：連接至centos7控制臺，用fdisk -l命令查看 是否有新的磁盤加入到虛擬機？
[root@node1 ~]# virsh console centos7 連接到域 centos7 換碼符為 ^] CentOS Linux 7 (Core) Kernel 3.10.0-693.el7.x86_64 on an x86_64 localhost login: root Password: Last login: Wed Aug 19 09:30:56 on tty1 [root@localhost ~]# fdisk -l Disk /dev/vda: 10.7 GB, 10737418240 bytes, 20971520 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk label type: dos Disk identifier: 0x000a5c54 Device Boot Start End Blocks Id System /dev/vda1 * 2048 1050623 524288 83 Linux /dev/vda2 1050624 20971519 9960448 8e Linux LVM Disk /dev/mapper/centos-root: 10.2 GB, 10192158720 bytes, 19906560 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk /dev/mapper/centos-swap: 4 MB, 4194304 bytes, 8192 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk /dev/vdb: 2148 MB, 2148073472 bytes, 4195456 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes [root@localhost ~]#
提示：可以看到有一個vdb的磁盤已經被虛擬機識別；
在虛擬機內部對/dev/vdb進行磁區，并格式化
[root@localhost ~]# fdisk /dev/vdb
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0xe6bebed1.
Command (m for help): p
Disk /dev/vdb: 2148 MB, 2148073472 bytes, 4195456 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0xe6bebed1
Device Boot Start End Blocks Id System
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p): p
Partition number (1-4, default 1):
First sector (2048-4195455, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-4195455, default 4195455):
Using default value 4195455
Partition 1 of type Linux and of size 2 GiB is set
Command (m for help): p
Disk /dev/vdb: 2148 MB, 2148073472 bytes, 4195456 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0xe6bebed1
Device Boot Start End Blocks Id System
/dev/vdb1 2048 4195455 2096704 83 Linux
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[root@localhost ~]# mkfs.xfs /dev/vdb1
meta-data=https://www.cnblogs.com/dev/vdb1 isize=512 agcount=4, agsize=131044 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0, sparse=0
data = bsize=4096 blocks=524176, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=2560, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
[root@localhost ~]#
提示：到此我們新加的硬碟就可以實作掛載使用了；
掛載/dev/vdb1到/mnt
[root@localhost ~]# df -TH Filesystem Type Size Used Avail Use% Mounted on /dev/mapper/centos-root xfs 11G 940M 9.3G 10% / devtmpfs devtmpfs 509M 0 509M 0% /dev tmpfs tmpfs 521M 0 521M 0% /dev/shm tmpfs tmpfs 521M 14M 507M 3% /run tmpfs tmpfs 521M 0 521M 0% /sys/fs/cgroup /dev/vda1 xfs 534M 124M 410M 24% /boot tmpfs tmpfs 105M 0 105M 0% /run/user/0 [root@localhost ~]# mount /dev/vdb1 /mnt [root@localhost ~]# df -Th Filesystem Type Size Used Avail Use% Mounted on /dev/mapper/centos-root xfs 9.5G 897M 8.7G 10% / devtmpfs devtmpfs 486M 0 486M 0% /dev tmpfs tmpfs 497M 0 497M 0% /dev/shm tmpfs tmpfs 497M 13M 484M 3% /run tmpfs tmpfs 497M 0 497M 0% /sys/fs/cgroup /dev/vda1 xfs 509M 119M 391M 24% /boot tmpfs tmpfs 100M 0 100M 0% /run/user/0 /dev/vdb1 xfs 2.0G 33M 2.0G 2% /mnt [root@localhost ~]#
3、示例：動態將插入到虛擬機上的磁盤拆卸下來；
[root@node1 ~]# virsh domblklist centos7
目標 源
------------------------------------------------
vda /kvm/images/centos7.qcow2
vdb /kvm/images/c1.img
hda -
[root@node1 ~]# virsh help detach-disk
NAME
detach-disk - 分離磁盤設備
SYNOPSIS
detach-disk <domain> <target> [--persistent] [--config] [--live] [--current] [--print-xml]
DESCRIPTION
分離磁盤設備，
OPTIONS
[--domain] <string> domain name, id or uuid
[--target] <string> 磁盤設備目標
--persistent 讓實時更改持久
--config 影響下一次引導
--live 影響運行的域
--current 影響當前域
--print-xml print XML document rather than detach the disk
[root@node1 ~]# virsh detach-disk centos7 vdb
成功分離磁盤
[root@node1 ~]# virsh domblklist centos7
目標 源
------------------------------------------------
vda /kvm/images/centos7.qcow2
hda -
[root@node1 ~]#
提示：拆除硬碟可以直接使用virsh detach-disk 直接拆卸即可；
驗證：鏈接到虛擬機內部查看磁盤是否被拆卸了？
[root@node1 ~]# virsh console centos7 連接到域 centos7 換碼符為 ^] [root@localhost ~]# fdisk -l Disk /dev/vda: 10.7 GB, 10737418240 bytes, 20971520 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk label type: dos Disk identifier: 0x000a5c54 Device Boot Start End Blocks Id System /dev/vda1 * 2048 1050623 524288 83 Linux /dev/vda2 1050624 20971519 9960448 8e Linux LVM Disk /dev/mapper/centos-root: 10.2 GB, 10192158720 bytes, 19906560 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk /dev/mapper/centos-swap: 4 MB, 4194304 bytes, 8192 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes [root@localhost ~]#
提示：可以看到在虛擬機內部就只有vda沒有vdb了，說明我們把磁盤成功拆除了；
查看拆除下來的磁盤資訊
[root@node1 ~]# qemu-img info /kvm/images/c1.img image: /kvm/images/c1.img file format: raw virtual size: 2.0G (2148073472 bytes) disk size: 11M [root@node1 ~]#
提示：這里需要說明一下，我們在附加磁盤到虛擬內部以后，如果對磁盤進行了磁區格式化，它的格式默認會變成raw格式；
4、示例：給虛擬機做快照；
[root@node1 ~]# virsh help snapshot-create-as
NAME
snapshot-create-as - 使用一組引數生成快照
SYNOPSIS
snapshot-create-as <domain> [--name <string>] [--description <string>] [--print-xml] [--no-metadata] [--halt] [--disk-only] [--reuse-external] [--quiesce] [--atomic] [--live] [--memspec <string>] [[--diskspec] <string>]...
DESCRIPTION
使用一組引數生成快照（磁盤和 RAM）
OPTIONS
[--domain] <string> domain name, id or uuid
--name <string> 快照名稱
--description <string> 快照描述
--print-xml 輸出 XML 檔案而不是生成 XML
--no-metadata 提取快照但不生成元資料
--halt 生成快照后停止域
--disk-only 捕獲磁盤狀態而不是 vm 狀態
--reuse-external 重新使用任意現有外部檔案
--quiesce 靜默虛擬機的檔案系統
--atomic 需要自動操作
--live 提取實時快照
--memspec <string> 記憶體屬性：[file=]name[,snapshot=type]
[--diskspec] <string> 磁盤屬性: disk[,snapshot=type][,driver=type][,file=name]
[root@node1 ~]# virsh snapshot-create-as centos7 --name centos7-snap1 --description "touch test file before"
已生成域快照 centos7-snap1
[root@node1 ~]# virsh snapshot-list centos7
名稱 生成時間 狀態
------------------------------------------------------------
centos7-snap1 2017-03-29 02:44:58 +0800 running
[root@node1 ~]#
提示：以上命令是使用命令列引數來創建虛擬機快照，它默認會把快照的組態檔存盤到/var/lib/libvirt/qemu/snapshot/虛擬機名稱/快照名稱.xml；
查看快照檔案
[root@node1 ~]# ll /var/lib/libvirt/qemu/snapshot/
總用量 0
drwxr-xr-x 2 root root 31 3月 29 02:45 centos7
[root@node1 ~]# tree /var/lib/libvirt/qemu/snapshot/
/var/lib/libvirt/qemu/snapshot/
└── centos7
└── centos7-snap1.xml
1 directory, 1 file
[root@node1 ~]# cat /var/lib/libvirt/qemu/snapshot/centos7/centos7-snap1.xml
<!--
WARNING: THIS IS AN AUTO-GENERATED FILE. CHANGES TO IT ARE LIKELY TO BE
OVERWRITTEN AND LOST. Changes to this xml configuration should be made using:
virsh snapshot-edit
or other application using the libvirt API.
-->
<domainsnapshot>
<name>centos7-snap1</name>
<description>touch test file before</description>
<state>running</state>
<creationTime>1490726698</creationTime>
<memory snapshot='internal'/>
<disks>
<disk name='vda' snapshot='internal'/>
<disk name='hda' snapshot='no'/>
</disks>
<domain type='kvm'>
<name>centos7</name>
<uuid>a15b793e-055b-4c91-89a5-ceba0c7ec98d</uuid>
<memory unit='KiB'>1048576</memory>
<currentMemory unit='KiB'>1048576</currentMemory>
<vcpu placement='static'>2</vcpu>
<resource>
<partition>/machine</partition>
</resource>
<os>
<type arch='x86_64' machine='pc-i440fx-rhel7.0.0'>hvm</type>
<boot dev='hd'/>
</os>
<features>
<acpi/>
<apic/>
</features>
<cpu mode='custom' match='exact' check='partial'>
<model fallback='forbid'>Broadwell</model>
</cpu>
<clock offset='utc'>
<timer name='rtc' tickpolicy='catchup'/>
<timer name='pit' tickpolicy='delay'/>
<timer name='hpet' present='no'/>
</clock>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>destroy</on_crash>
<pm>
<suspend-to-mem enabled='no'/>
<suspend-to-disk enabled='no'/>
</pm>
<devices>
<emulator>/usr/libexec/qemu-kvm</emulator>
<disk type='file' device='disk'>
<driver name='qemu' type='qcow2'/>
<source file='/kvm/images/centos7.qcow2'/>
<target dev='vda' bus='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
</disk>
<disk type='file' device='cdrom'>
<driver name='qemu' type='raw'/>
<target dev='hda' bus='ide'/>
<readonly/>
<address type='drive' controller='0' bus='0' target='0' unit='0'/>
</disk>
<controller type='usb' index='0' model='ich9-ehci1'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x7'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci1'>
<master startport='0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0' multifunction='on'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci2'>
<master startport='2'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x1'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci3'>
<master startport='4'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x2'/>
</controller>
<controller type='ide' index='0'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
</controller>
<controller type='virtio-serial' index='0'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
</controller>
<controller type='pci' index='0' model='pci-root'/>
<interface type='network'>
<mac address='52:54:00:ff:51:f1'/>
<source network='default'/>
<model type='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
</interface>
<serial type='pty'>
<target type='isa-serial' port='0'>
<model name='isa-serial'/>
</target>
</serial>
<console type='pty'>
<target type='serial' port='0'/>
</console>
<channel type='unix'>
<target type='virtio' name='org.qemu.guest_agent.0'/>
<address type='virtio-serial' controller='0' bus='0' port='1'/>
</channel>
<input type='tablet' bus='usb'>
<address type='usb' bus='0' port='1'/>
</input>
<input type='mouse' bus='ps2'/>
<input type='keyboard' bus='ps2'/>
<graphics type='vnc' port='-1' autoport='yes' listen='0.0.0.0'>
<listen type='address' address='0.0.0.0'/>
</graphics>
<video>
<model type='cirrus' vram='16384' heads='1' primary='yes'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
</video>
<memballoon model='virtio'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
</memballoon>
<rng model='virtio'>
<backend model='random'>/dev/urandom</backend>
<address type='pci' domain='0x0000' bus='0x00' slot='0x08' function='0x0'/>
</rng>
</devices>
</domain>
<cookie>
<cpu mode='custom' match='exact' check='full'>
<model fallback='forbid'>Broadwell</model>
<feature policy='require' name='hypervisor'/>
<feature policy='disable' name='erms'/>
<feature policy='require' name='xsaveopt'/>
</cpu>
</cookie>
<active>1</active>
</domainsnapshot>
[root@node1 ~]#
5、示例：還原虛擬機到做快照時的狀態；
首先連接至虛擬機內不在root目錄下新建一個測驗檔案，然后將虛擬機關機，然后在還原到創建測驗檔案前端快照狀態，然后開機，看看虛擬機是否回到測驗檔案創建前的狀態了？
[root@node1 ~]# virsh console centos7 連接到域 centos7 換碼符為 ^] [root@localhost ~]# ls anaconda-ks.cfg [root@localhost ~]# echo "this is test file" >test.xml [root@localhost ~]# cat test.xml this is test file [root@localhost ~]# [root@node1 ~]# virsh destroy centos7 域 centos7 被洗掉 [root@node1 ~]# virsh list --all Id 名稱 狀態 ---------------------------------------------------- - centos7 關閉 [root@node1 ~]# virsh domstate centos7 關閉 [root@node1 ~]#
將虛擬機歡迎到剛才創建的快照狀態
[root@node1 ~]# virsh snapshot-list centos7
名稱 生成時間 狀態
------------------------------------------------------------
centos7-snap1 2017-03-29 02:44:58 +0800 running
[root@node1 ~]# virsh snapshot-revert centos7 centos7-snap1
[root@node1 ~]# virsh list --all
Id 名稱 狀態
----------------------------------------------------
3 centos7 running
[root@node1 ~]# virsh snapshot-current centos7
<domainsnapshot>
<name>centos7-snap1</name>
<description>touch test file before</description>
<state>running</state>
<creationTime>1490726698</creationTime>
<memory snapshot='internal'/>
<disks>
<disk name='vda' snapshot='internal'/>
<disk name='hda' snapshot='no'/>
</disks>
<domain type='kvm'>
<name>centos7</name>
<uuid>a15b793e-055b-4c91-89a5-ceba0c7ec98d</uuid>
<memory unit='KiB'>1048576</memory>
<currentMemory unit='KiB'>1048576</currentMemory>
<vcpu placement='static'>2</vcpu>
<resource>
<partition>/machine</partition>
</resource>
<os>
<type arch='x86_64' machine='pc-i440fx-rhel7.0.0'>hvm</type>
<boot dev='hd'/>
</os>
<features>
<acpi/>
<apic/>
</features>
<cpu mode='custom' match='exact' check='partial'>
<model fallback='forbid'>Broadwell</model>
</cpu>
<clock offset='utc'>
<timer name='rtc' tickpolicy='catchup'/>
<timer name='pit' tickpolicy='delay'/>
<timer name='hpet' present='no'/>
</clock>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>destroy</on_crash>
<pm>
<suspend-to-mem enabled='no'/>
<suspend-to-disk enabled='no'/>
</pm>
<devices>
<emulator>/usr/libexec/qemu-kvm</emulator>
<disk type='file' device='disk'>
<driver name='qemu' type='qcow2'/>
<source file='/kvm/images/centos7.qcow2'/>
<target dev='vda' bus='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
</disk>
<disk type='file' device='cdrom'>
<driver name='qemu' type='raw'/>
<target dev='hda' bus='ide'/>
<readonly/>
<address type='drive' controller='0' bus='0' target='0' unit='0'/>
</disk>
<controller type='usb' index='0' model='ich9-ehci1'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x7'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci1'>
<master startport='0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0' multifunction='on'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci2'>
<master startport='2'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x1'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci3'>
<master startport='4'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x2'/>
</controller>
<controller type='ide' index='0'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
</controller>
<controller type='virtio-serial' index='0'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
</controller>
<controller type='pci' index='0' model='pci-root'/>
<interface type='network'>
<mac address='52:54:00:ff:51:f1'/>
<source network='default'/>
<model type='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
</interface>
<serial type='pty'>
<target type='isa-serial' port='0'>
<model name='isa-serial'/>
</target>
</serial>
<console type='pty'>
<target type='serial' port='0'/>
</console>
<channel type='unix'>
<target type='virtio' name='org.qemu.guest_agent.0'/>
<address type='virtio-serial' controller='0' bus='0' port='1'/>
</channel>
<input type='tablet' bus='usb'>
<address type='usb' bus='0' port='1'/>
</input>
<input type='mouse' bus='ps2'/>
<input type='keyboard' bus='ps2'/>
<graphics type='vnc' port='-1' autoport='yes' listen='0.0.0.0'>
<listen type='address' address='0.0.0.0'/>
</graphics>
<video>
<model type='cirrus' vram='16384' heads='1' primary='yes'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
</video>
<memballoon model='virtio'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
</memballoon>
<rng model='virtio'>
<backend model='random'>/dev/urandom</backend>
<address type='pci' domain='0x0000' bus='0x00' slot='0x08' function='0x0'/>
</rng>
</devices>
</domain>
<cookie>
<cpu mode='custom' match='exact' check='full'>
<model fallback='forbid'>Broadwell</model>
<feature policy='require' name='hypervisor'/>
<feature policy='disable' name='erms'/>
<feature policy='require' name='xsaveopt'/>
</cpu>
</cookie>
</domainsnapshot>
[root@node1 ~]#
提示：從上面的資訊可以看到，我們還原虛擬機到我們做的快照狀態后，虛擬機處于運行狀態，并且當前虛擬機快照是centos7_snap1這個快照是我們在新建測驗檔案前創建的快照；
驗證：連接虛擬控制臺，查看測驗檔案是否還存在？
[root@node1 ~]# virsh console centos7 連接到域 centos7 換碼符為 ^] [root@localhost ~]# ls anaconda-ks.cfg [root@localhost ~]# pwd /root [root@localhost ~]#
提示：可以看到測驗檔案沒有了；
查看當前虛擬機磁盤檔案資訊
[root@node1 ~]# virsh domblklist centos7
目標 源
------------------------------------------------
vda /kvm/images/centos7.qcow2
hda -
[root@node1 ~]# qemu-img info /kvm/images/centos7.qcow2
image: /kvm/images/centos7.qcow2
file format: qcow2
virtual size: 10G (10737418240 bytes)
disk size: 1.5G
cluster_size: 65536
Snapshot list:
ID TAG VM SIZE DATE VM CLOCK
1 centos7-snap1 294M 2017-03-29 02:44:58 01:33:32.709
Format specific information:
compat: 1.1
lazy refcounts: false
[root@node1 ~]#
提示：可以看到磁盤資訊上有我們給虛擬機做到快照資訊；
有關虛擬機快照的命令有
[root@node1 ~]# virsh help snapshot
Snapshot (help keyword 'snapshot'):
snapshot-create 使用 XML 生成快照
snapshot-create-as 使用一組引數生成快照
snapshot-current 獲取或者設定當前快照
snapshot-delete 洗掉域快照
snapshot-dumpxml 為域快照轉儲 XML
snapshot-edit 編輯快照 XML
snapshot-info 快照資訊
snapshot-list 為域列出快照
snapshot-parent 獲取快照的上級快照名稱
snapshot-revert 將域轉換為快照
[root@node1 ~]#
提示：以上命令和virsh 其他命令都比較類似，我這里就不過多闡述，不清楚命令語法可以查看每個命令的幫助資訊來使用；
轉載請註明出處，本文鏈接：https://www.uj5u.com/caozuo/1764.html
標籤：Linux
下一篇：NFS 服務的介紹與搭建