A plurality of image copies can be allocated physical partitions, thereby improving the availability of data. When a disk fails and the physical partition becomes unavailable, you can still access the data on available disk mirroring. LVM mirroring is performed in the logical volume.
system version
# cat /etc/centos-release
CentOS Linux release 7.2.1511 (Core)
Disk
[root@host-192-168-100-19 ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
vda 252:0 0 10G 0 disk
├─vda1 252:1 0 500M 0 part /boot
└─vda2 252:2 0 9.5G 0 part
├─centos-root 253:0 0 8.5G 0 lvm /
└─centos-swap 253:1 0 1G 0 lvm [SWAP]
vdb 252:16 0 5G 0 disk
vdc 252:32 0 5G 0 disk
vdd 252:48 0 5G 0 disk
Create a physical volume
# pvcreate /dev/vdb /dev/vdc
Create a volume group
# vgcreate wyl /dev/vdb /dev/vdc
Create a mirrored volume
lvcreate -L 3G -m1 -n mirror wyl /dev/vdc /dev/vdb
Description:
Use -ml parameter flag to create mirrored; -L is used to set the size of the mirrored volume 3G; -n argument is used to specify the mirror name mirror. This image consists of two parts: vdb vdc and the copy volume is a data volume and partition
view the status of logical
view the current status of the devices lvm:
# lvs -a -o +devices
Lv for new format and mirror mount
# mkfs.xfs /dev/wyl/mirror
# mkdir /mirror
# mount /dev/wyl/mirror /mirror/
Reading and writing test partition ok
# cd /mirror/
# echo "it's ok" >test
# cat test
it's ok
Lvm to destroy the mirror
# dd if=/dev/zero of=/dev/vdc count=10
You can see in the mirror lv / dev / vdc became unknown after destruction
The broken equipment is removed from the wyl in:
# vgreduce --removemissing --force wyl
View lvm devices in the current state:
# lvs -a -o +devices
Mirror data recovery (without unmounting process logical volumes)
in adding a new wyl pv, the data recovery:
# vgextend wyl /dev/vdd
Unset mirrored volume
# lvconvert -m0 /dev/wyl/mirror
Data migration, data synchronization to the vdc vdd in
# lvconvert -m1 /dev/wyl/mirror /dev/vdd /dev/vdc
test
# cd /mirror/
# echo 'it is ok 2' >test2
# cat test
it's ok