LVM snapshot案例

1.檢視vg是否有剩餘空間，若不夠需先擴容

[[email protected] ~]# vgs myvo
  VG   #PV #LV #SN Attr   VSize   VFree
  myvo   1   1   0 wz--n- <30.00g    0 
[[email protected] ~]# vgextend myvo /dev/sdc
  Physical volume "/dev/sdc" successfully created.
  Volume group "myvo" successfully extended
[[email protected] ~]# vgs myvo
  VG   #PV #LV #SN Attr   VSize  VFree  
  myvo   2   1   0 wz--n- 59.99g <30.00g

           

2.建立快照

[[email protected] ~]# lvcreate -L 50M -n vo-snap -s /dev/myvo/vo
  Rounding up size to full physical extent 52.00 MiB
  Logical volume "vo-snap" created.
[[email protected] ~]# lvs
  LV      VG     Attr       LSize    Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  root    centos -wi-ao---- <487.00g                                                    
  swap    centos -wi-ao----    2.00g                                                    
  vo      myvo   owi-aos---  <30.00g                                                    
  vo-snap myvo   swi-a-s---   52.00m      vo     0.02        
           

3.挂載快照

[[email protected] ~]# mount -o ro /dev/myvo/vo-snap /mnt  //以隻讀的方式挂載
[[email protected] ~]# df -h
檔案系統                   容量  已用  可用 已用% 挂載點
/dev/mapper/centos-root    487G   16G  472G    4% /
devtmpfs                   470M     0  470M    0% /dev
tmpfs                      487M  4.0K  487M    1% /dev/shm
tmpfs                      487M  8.4M  478M    2% /run
tmpfs                      487M     0  487M    0% /sys/fs/cgroup
/dev/sda1                 1014M  166M  849M   17% /boot
tmpfs                       98M   12K   98M    1% /run/user/42
tmpfs                       98M     0   98M    0% /run/user/0
/dev/mapper/myvo-vo         29G  3.1G   24G   12% /data
/dev/mapper/myvo-vo--snap   29G  3.1G   24G   12% /mnt
[[email protected] ~]# ls /data /mnt/
/data:
lost+found  mysql

/mnt/:
lost+found  mysql
           

如果檔案系統為XFS 格式的 不支援直接挂載 需要加 -o nouuid選項 例如

mount -o nouuid,ro /dev/myvo/vo-snap /mnt

删除快照方式：

[[email protected] ~]# umount /mnt/

[[email protected] ~]# lvremove /dev/myvo/vo-snap //或者加-f方式以非互動式方式删除

Do you really want to remove active logical volume myvo/vo-snap? [y/n]: y

Logical volume “vo-snap” successfully removed

[[email protected] ~]# lvs

LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert

root centos -wi-ao---- <487.00g

swap centos -wi-ao---- 2.00g

vo myvo -wi-ao---- <30.00g