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