在将几块盘做LVM时，遇到一个之前都没遇到过的问题:

root@ubuntu:~# pvcreate /dev/sdc1

Can't open /dev/sdc1 exclusively. Mounted filesystem?

首先第一反应就是查看这个分区是否已经在使用了，但是没有。

查看硬盘的一些信息:

root@ubuntu:~# cat /proc/partitions

major minor #blocks name

8 0 488386584 sda

8 1 16777216 sda1

8 2 471608344 sda2

8 32 488386584 sdc

8 33 488386584 sdc1

8 16 488386584 sdb

8 17 488385560 sdb1

8 48 488386584 sdd

8 49 488384001 sdd1

254 0 838860800 dm-0

254 1 4194304 dm-1

254 2 488386584 dm-2

254 3 488386584 dm-3

254 5 488384001 dm-5

254 4 488384001 dm-4

root@ubuntu:~# fdisk /dev/sdc -l

Disk /dev/sdc: 500.1 GB, 500107862016 bytes

81 heads, 63 sectors/track, 191411 cylinders, total 976773168 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 identifier: 0xbbbab9b8

Device Boot Start End Blocks Id System

/dev/sdc1 2048 976773167 488385560 8e Linux LVM

接着看一些底层的信息:

dmsetup 是一个底层的逻辑卷管理， dm 应该是 Device Mapper的简称。

root@ubuntu:~# dmsetup status

35000c50026716847: 0 976773168 multipath 2 0 0 0 1 1 A 0 1 0 8:48 A 0

vg_data-lv_home: 0 976764928 linear

vg_data-lv_home: 976764928 700956672 linear

35000c5002670f03e: 0 976773168 multipath 2 0 0 0 1 1 A 0 1 0 8:32 A 0

35000c5002670f03e-part1: 0 976768002 linear

35000c50026716847-part1: 0 976768002 linear

vg_data-lv_swap: 0 8388608 linear

root@ubuntu:~# dmsetup ls

35000c50026716847 (254, 2)

vg_data-lv_home (254, 0)

35000c5002670f03e (254, 3)

35000c5002670f03e-part1 (254, 5)

35000c50026716847-part1 (254, 4)

vg_data-lv_swap (254, 1)

可以看到 35000c5002670f03e 和 35000c50026716847 组成了multipath(多路径)

root@ubuntu:~# multipath -ll

35000c50026716847 dm-2 ATA,GB0500EAFJH

size=466G features='0' hwhandler='0' wp=rw

`-+- policy='round-robin 0' prio=1 status=active

`- 3:0:0:0 sdd 8:48 active ready running

35000c5002670f03e dm-3 ATA,GB0500EAFJH

size=466G features='0' hwhandler='0' wp=rw

`-+- policy='round-robin 0' prio=1 status=active

`- 2:0:0:0 sdc 8:32 active ready running

root@ubuntu:~# ll /dev/mapper/

total 0

drwxr-xr-x 2 root root 180 Jun 28 01:39 ./

drwxr-xr-x 14 root root 13060 Jun 28 17:17 ../

lrwxrwxrwx 1 root root 7 Jun 28 01:39 35000c5002670f03e -> ../dm-3

lrwxrwxrwx 1 root root 7 Jun 28 01:39 35000c5002670f03e-part1 -> ../dm-5

lrwxrwxrwx 1 root root 7 Jun 28 01:39 35000c50026716847 -> ../dm-2

lrwxrwxrwx 1 root root 7 Jun 28 01:39 35000c50026716847-part1 -> ../dm-4

crw------T 1 root root 10, 236 Jun 28 01:39 control

lrwxrwxrwx 1 root root 7 Jun 28 01:39 vg_data-lv_home -> ../dm-0

lrwxrwxrwx 1 root root 7 Jun 28 01:39 vg_data-lv_swap -> ../dm-1

使用 dmsetup remove xxx 移除掉就可以创建PV了:

root@ubuntu:~# dmsetup remove 35000c5002670f03e-part1

root@ubuntu:~# dmsetup remove 35000c5002670f03e

root@ubuntu:~# pvcreate /dev/sdc1

Physical volume "/dev/sdc1" successfully created

也可以使用dmsetup remove_all移除所有。

TODO: 继续研究