lvm的镜像备份功能

首先&＃xff0c;先创建3个lvm类型的分区&＃xff1a;

Device Boot Start End Blocks Id System
/dev/sdb1 1 52 417658&＃43; 8e Linux LVM
/dev/sdb2 53 104 417690 8e Linux LVM
/dev/sdb3 105 111 56227&＃43; 8e Linux LVM

创建物理卷&＃xff1a;

pvcreate /dev/sdb1 /dev/sdb2 /dev/sdb3Physical volume "/dev/sdb1" successfully createdPhysical volume "/dev/sdb2" successfully createdPhysical volume "/dev/sdb3" successfully created

查看物理卷&＃xff1a;

pvsPV VG Fmt Attr PSize PFree/dev/sda2 vg_mail lvm2 a-- 19.51g 0/dev/sdb1 lvm2 a-- 407.87m 407.87m/dev/sdb2 lvm2 a-- 407.90m 407.90m/dev/sdb3 lvm2 a-- 54.91m 54.91m

创建卷组&＃xff1a;

vgcreate myvg /dev/sdb1 /dev/sdb2 /dev/sdb3Volume group "myvg" successfully created

查看卷组&＃xff1a;

vgsVG #PV #LV #SN Attr VSize VFreemyvg 3 0 0 wz--n- 860.00m 860.00mvg_mail 1 2 0 wz--n- 19.51g 0

创建LVM镜像逻辑卷&＃xff1a;

lvcreate -L 300M -n mylv -m1 myvgLogical volume "mylv" created

再来查看卷组大小&＃xff1a;

vgsVG #PV #LV #SN Attr VSize VFreemyvg 3 1 0 wz--n- 860.00m 256.00mvg_mail 1 2 0 wz--n- 19.51g 0

通过和上面的比较&＃xff0c;不难发现&＃xff0c;这里我创建的是300M的逻辑卷&＃xff0c;而卷组却减少了600M左右&＃xff0c;因为我们-m1这个参数使得我们的逻辑卷有了镜像的功能。

再来查看lv中各设备的状态&＃xff1a;

lvs -a -o &＃43;devicesLV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert Devices mylv myvg mwi-a-m-- 300.00m mylv_mlog 100.00 mylv_mp_w_picpath_0(0),mylv_mp_w_picpath_1(0)[mylv_mp_w_picpath_0] myvg iwi-aom-- 300.00m /dev/sdb1(0) [mylv_mp_w_picpath_1] myvg iwi-aom-- 300.00m /dev/sdb2(0) [mylv_mlog] myvg lwi-aom-- 4.00m /dev/sdb3(0) lv_root vg_mail -wi-ao--- 17.57g /dev/sda2(0) lv_swap vg_mail -wi-ao--- 1.94g /dev/sda2(4498)

这里我们可以看出,sdb1和sdb2为数据卷和镜像卷&＃xff0c;sdb3为日志卷

格式化和挂载&＃xff1a;

mkfs.ext4 /dev/myvg/mylv
mount /dev/myvg/mylv /mnt/

现在我们先向lv中写入数据然后损坏sdb1&＃xff1a;

dd if&＃61;/dev/zero of&＃61;/mnt/jj bs&＃61;1M count&＃61;100
100&＃43;0 records in
100&＃43;0 records out
104857600 bytes (105 MB) copied, 1.13108 s, 92.7 MB/s

dd if&＃61;/dev/zero of&＃61;/dev/sdb1 count&＃61;10

再次查看lv中个设备的状态&＃xff1a;

lvs -a -o &＃43;devices Couldn&＃39;t find device with uuid zcHbJz-hec4-bLBX-cuKd-4Sv9-kgOS-3ZyR8O.LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert Devices mylv myvg mwi-aom-p 300.00m mylv_mlog 100.00 mylv_mp_w_picpath_0(0),mylv_mp_w_picpath_1(0)[mylv_mp_w_picpath_0] myvg iwi-aom-p 300.00m unknown device(0) [mylv_mp_w_picpath_1] myvg iwi-aom-- 300.00m /dev/sdb2(0) [mylv_mlog] myvg lwi-aom-- 4.00m /dev/sdb3(0) lv_root vg_mail -wi-ao--- 17.57g /dev/sda2(0) lv_swap vg_mail -wi-ao--- 1.94g /dev/sda2(4498)

这里我们可以看到sdb1变成了unknown device。但是这时在挂载点下&＃xff0c;我们还是可以进行读写操作的。

把坏掉的设备从卷组中移除&＃xff1a;

vgreduce --removemissing --force myvgCouldn&＃39;t find device with uuid zcHbJz-hec4-bLBX-cuKd-4Sv9-kgOS-3ZyR8O.Wrote out consistent volume group myvg
[root&＃64;mail mnt]# lvs -a -o &＃43;devices LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert Devices mylv myvg -wi-ao--- 300.00m /dev/sdb2(0) lv_root vg_mail -wi-ao--- 17.57g /dev/sda2(0) lv_swap vg_mail -wi-ao--- 1.94g /dev/sda2(4498)

已经移除了。然后我们重新挂载&＃xff0c;可看到之前写的jj那个文件还在。

mount -o remount /mnt/
ls
jj lost&＃43;found

我们再创建sdb4来取代sdb1的位置

Device Boot Start End Blocks Id System
/dev/sdb1 1 52 417658&＃43; 8e Linux LVM
/dev/sdb2 53 104 417690 8e Linux LVM
/dev/sdb3 105 111 56227&＃43; 8e Linux LVM
/dev/sdb4 112 163 417690 8e Linux LVM
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.
[root&＃64;mail mnt]# partx -a
call: partx -opts [device] wholedisk
[root&＃64;mail mnt]# partx -a /dev/sdb
BLKPG: Device or resource busy
error adding partition 1
BLKPG: Device or resource busy
error adding partition 2
BLKPG: Device or resource busy
error adding partition 3
[root&＃64;mail mnt]# pvcreate /dev/sdb4Physical volume "/dev/sdb4" successfully created
[root&＃64;mail mnt]# vgextend myvg /dev/sdb4Volume group "myvg" successfully extended

扩展并查看lv中的设备&＃xff1a;

lvconvert -m1 /dev/myvg/mylv /dev/sdb4myvg/mylv: Converted: 0.0%myvg/mylv: Converted: 100.0%
[root&＃64;mail mnt]# lvs -a -o &＃43;devicesLV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert Devices mylv myvg mwi-aom-- 300.00m mylv_mlog 100.00 mylv_mp_w_picpath_0(0),mylv_mp_w_picpath_1(0)[mylv_mp_w_picpath_0] myvg iwi-aom-- 300.00m /dev/sdb2(0) [mylv_mp_w_picpath_1] myvg iwi-aom-- 300.00m /dev/sdb4(0) [mylv_mlog] myvg lwi-aom-- 4.00m /dev/sdb4(75) lv_root vg_mail -wi-ao--- 17.57g /dev/sda2(0) lv_swap vg_mail -wi-ao--- 1.94g /dev/sda2(4498)
[root&＃64;mail mnt]#

可以看到sdb2和sdb4为数据卷和镜像卷了。这就是lvm的镜像。lvm的功能很强大&＃xff0c;可以在man文档最后的Examples中看到。