在前面的环境基础上进行进一步测试：
扩展LVM：
从网上下载一个测试文件，放到LVM2分区中：
[root@DanCentOS67 LV2]# wget http://daneaststorage.blob.core.chinacloudapi.cn/demo/Azure.pdf
--2017-03-09 15:13:21-- http://daneaststorage.blob.core.chinacloudapi.cn/demo/Azure.pdf
Resolving daneaststorage.blob.core.chinacloudapi.cn... 42.159.208.78
Connecting to daneaststorage.blob.core.chinacloudapi.cn|42.159.208.78|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 7670041 (7.3M) [application/pdf]
Saving to: “Azure.pdf”
100%[=============================================================================================================================>] 7,670,041 --.-K/s in 0.06s
2017-03-09 15:13:21 (123 MB/s) - “Azure.pdf” saved [7670041/7670041]
[root@DanCentOS67 LV2]# ll
total 7508
-rw-r--r--. 1 root root 7670041 Jul 6 2016 Azure.pdf
drwx------. 2 root root 16384 Mar 9 15:02 lost+found
将之前创建好的 Physical Volume /dev/md125 扩展到VolGroup1中：
[root@DanCentOS67 LV2]# vgextend VolGroup1 /dev/md125
Volume group "VolGroup1" successfully extended
查看 Volume Group的状态，可以看到已经加入的新的空间：
[root@DanCentOS67 LV2]# vgdisplay
--- Volume group ---
VG Name VolGroup1
System ID
Format lvm2
Metadata Areas 3
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 3
Act PV 3
VG Size 24.94 GiB
PE Size 4.00 MiB
Total PE 6385
Alloc PE / Size 5108 / 19.95 GiB
Free PE / Size 1277 / 4.99 GiB
VG UUID dsTlXU-D3Y5-Fqb3-wCOl-LHmj-7Qyf-hXU186
扩展 Logic Volume 的大小：
[root@DanCentOS67 LV2]# lvextend /dev/mapper/VolGroup1-LogicalVol2 /dev/md125
Size of logical volume VolGroup1/LogicalVol2 changed from 10.19 GiB (2608 extents) to 15.18 GiB (3885 extents).
Logical volume LogicalVol2 successfully resized
也可以将分区扩展到某个大小（下面这条命令将分区扩展到1024MiB）：
lvextend -L1024 /dev/mapper/VolGroup1-LogicalVol2
或者在分区现在的大小上进一步扩展固定大小的空间（下面这条命令在现有大小的基础上继续增加100 MiB）：
lvextend -L+100 /dev/mapper/VolGroup1-LogicalVol2
扩展完成后，可以看到 /mnt/LV2 的大小实际没有发生变化：
[root@DanCentOS67 LV2]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 30G 2.0G 26G 7% /
tmpfs 6.9G 0 6.9G 0% /dev/shm
/dev/sdb1 133G 60M 126G 1% /mnt/resource
/dev/mapper/VolGroup1-LogicalVol1
9.5G 22M 9.0G 1% /mnt/LV1
/dev/mapper/VolGroup1-LogicalVol2
10G 33M 9.4G 1% /mnt/LV2
进一步使用 resize2fs 工具将文件系统的大小进行扩展：
[root@DanCentOS67 LV2]# resize2fs /dev/mapper/VolGroup1-LogicalVol2
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/mapper/VolGroup1-LogicalVol2 is mounted on /mnt/LV2; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 1
Performing an on-line resize of /dev/mapper/VolGroup1-LogicalVol2 to 3978240 (4k) blocks.
The filesystem on /dev/mapper/VolGroup1-LogicalVol2 is now 3978240 blocks long.
再次查看发现文件系统的大小已经变为新的大小（扩展成功）：
[root@DanCentOS67 LV2]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 30G 2.0G 26G 7% /
tmpfs 6.9G 0 6.9G 0% /dev/shm
/dev/sdb1 133G 60M 126G 1% /mnt/resource
/dev/mapper/VolGroup1-LogicalVol1
9.5G 22M 9.0G 1% /mnt/LV1
/dev/mapper/VolGroup1-LogicalVol2
15G 33M 15G 1% /mnt/LV2
文件也没有损坏或丢失：
[root@DanCentOS67 LV2]# ll
total 7508
-rw-r--r--. 1 root root 7670041 Jul 6 2016 Azure.pdf
drwx------. 2 root root 16384 Mar 9 15:02 lost+found
将 LVM 迁移到其他机器上：
将4块磁盘从原来的机器上分离下来，按照 c，d，e，f 的顺序依次挂载到另外一台机器上（另外一台机器原有一个分区 /dev/sdc，所以所有的分区号都向后串了一个）。
fdisk -l 查看分区的情况：
[root@DanCentOS65 daniel]# fdisk -l
……
Disk /dev/sdd: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xbd293e5b
Device Boot Start End Blocks Id System
/dev/sdd1 1 653 5245191 fd Linux raid autodetect
/dev/sdd2 654 1305 5237190 fd Linux raid autodetect
Disk /dev/md127: 10.7 GB, 10716446720 bytes
2 heads, 4 sectors/track, 2616320 cylinders
Units = cylinders of 8 * 512 = 4096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 524288 bytes / 1048576 bytes
Disk identifier: 0x00000000
Disk /dev/mapper/VolGroup1-LogicalVol1: 10.5 GB, 10485760000 bytes
255 heads, 63 sectors/track, 1274 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 524288 bytes / 1048576 bytes
Disk identifier: 0x00000000
Disk /dev/sde: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x13c704fe
Device Boot Start End Blocks Id System
/dev/sde1 1 653 5245191 fd Linux raid autodetect
/dev/sde2 654 1305 5237190 fd Linux raid autodetect
Disk /dev/md126: 10.7 GB, 10716446720 bytes
2 heads, 4 sectors/track, 2616320 cylinders
Units = cylinders of 8 * 512 = 4096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 524288 bytes / 1048576 bytes
Disk identifier: 0x00000000
Disk /dev/sdf: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x3273d383
Device Boot Start End Blocks Id System
/dev/sdf1 1 653 5245191 fd Linux raid autodetect
/dev/sdf2 654 1305 5237190 fd Linux raid autodetect
Disk /dev/sdg: 10.7 GB, 10737418240 bytes
255 heads, 63 sectors/track, 1305 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x6283a8a2
Device Boot Start End Blocks Id System
/dev/sdg1 1 653 5245191 fd Linux raid autodetect
/dev/sdg2 654 1305 5237190 fd Linux raid autodetect
Disk /dev/md125: 5358 MB, 5358223360 bytes
2 heads, 4 sectors/track, 1308160 cylinders
Units = cylinders of 8 * 512 = 4096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 524288 bytes / 524288 bytes
Disk identifier: 0x00000000
可以看到没有识别出 Logical Volume 2，所以我们从RAID 开始再重新检查一下：
[root@DanCentOS65 daniel]# mdadm --misc --detail /dev/md127
/dev/md127:
Version : 1.2
Creation Time : Thu Mar 9 14:43:25 2017
Raid Level : raid5
Array Size : 10465280 (9.98 GiB 10.72 GB)
Used Dev Size : 5232640 (4.99 GiB 5.36 GB)
Raid Devices : 3
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Thu Mar 9 15:37:38 2017
State : clean, degraded
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 512K
Name : DanCentOS67:127
UUID : 1a86a744:b01bd085:ee05717d:8ba86e4a
Events : 18
Number Major Minor RaidDevice State
0 8 49 0 active sync /dev/sdd1
2 0 0 2 removed
3 8 50 2 active sync /dev/sdd2
[root@DanCentOS65 daniel]# mdadm --misc --detail /dev/md126
/dev/md126:
Version : 1.2
Creation Time : Thu Mar 9 14:43:46 2017
Raid Level : raid5
Array Size : 10465280 (9.98 GiB 10.72 GB)
Used Dev Size : 5232640 (4.99 GiB 5.36 GB)
Raid Devices : 3
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Fri Mar 10 02:26:26 2017
State : clean, degraded
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 512K
Name : DanCentOS67:126
UUID : 72b40d3f:78790af8:d369e502:8547a8b1
Events : 21
Number Major Minor RaidDevice State
0 0 0 0 removed
1 8 82 1 active sync /dev/sdf2
3 8 81 2 active sync /dev/sdf1
[root@DanCentOS65 daniel]# mdadm --misc --detail /dev/md125
/dev/md125:
Version : 1.2
Creation Time : Thu Mar 9 14:43:55 2017
Raid Level : raid5
Array Size : 5232640 (4.99 GiB 5.36 GB)
Used Dev Size : 5232640 (4.99 GiB 5.36 GB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Thu Mar 9 15:37:38 2017
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 512K
Name : DanCentOS67:125
UUID : e74d96ff:12e1173d:f2d398ce:744d5f47
Events : 18
Number Major Minor RaidDevice State
0 8 97 0 active sync /dev/sdg1
2 8 98 1 active sync /dev/sdg2
可以看到 /dev/md127 和 /dev/md126 没有识别到/dev/sde1 和 /dev/sde2 两个分区。
查看这两个分区的状态：
[root@DanCentOS65 daniel]# mdadm --examine /dev/sde1
/dev/sde1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 1a86a744:b01bd085:ee05717d:8ba86e4a
Name : DanCentOS67:127
Creation Time : Thu Mar 9 14:43:25 2017
Raid Level : raid5
Raid Devices : 3
Avail Dev Size : 10482190 (5.00 GiB 5.37 GB)
Array Size : 10465280 (9.98 GiB 10.72 GB)
Used Dev Size : 10465280 (4.99 GiB 5.36 GB)
Data Offset : 8192 sectors
Super Offset : 8 sectors
Unused Space : before=8104 sectors, after=16910 sectors
State : clean
Device UUID : 3275b1fe:c1c7935c:e3d4928e:1740fc0c
Update Time : Fri Mar 10 02:22:57 2017
Bad Block Log : 512 entries available at offset 72 sectors
Checksum : b236682c - correct
Events : 23
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 1
Array State : .A. ('A' == active, '.' == missing, 'R' == replacing)
[root@DanCentOS65 daniel]# mdadm --examine /dev/sde2
/dev/sde2:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 72b40d3f:78790af8:d369e502:8547a8b1
Name : DanCentOS67:126
Creation Time : Thu Mar 9 14:43:46 2017
Raid Level : raid5
Raid Devices : 3
Avail Dev Size : 10466188 (4.99 GiB 5.36 GB)
Array Size : 10465280 (9.98 GiB 10.72 GB)
Used Dev Size : 10465280 (4.99 GiB 5.36 GB)
Data Offset : 8192 sectors
Super Offset : 8 sectors
Unused Space : before=8104 sectors, after=908 sectors
State : clean
Device UUID : 46862c7b:4db1cdb0:17a40a6c:91254c2e
Update Time : Thu Mar 9 15:52:42 2017
Bad Block Log : 512 entries available at offset 72 sectors
Checksum : db02d450 - correct
Events : 18
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 0
Array State : AAA ('A' == active, '.' == missing, 'R' == replacing)
可以看到，状态是好的，分区并未出现异常。
重新将两个分区加回 RAID 5 阵列中：
[root@DanCentOS65 daniel]# mdadm --manage /dev/md127 --add /dev/sde1
mdadm: re-added /dev/sde1
[root@DanCentOS65 daniel]# mdadm --manage /dev/md126 --add /dev/sde2
mdadm: added /dev/sde2
经过一段时间的Rebuild后，查看重新检查可以看到两个 RAID 5 阵列已经恢复：
[root@DanCentOS65 daniel]# mdadm --misc --detail /dev/md127
/dev/md127:
Version : 1.2
Creation Time : Thu Mar 9 14:43:25 2017
Raid Level : raid5
Array Size : 10465280 (9.98 GiB 10.72 GB)
Used Dev Size : 5232640 (4.99 GiB 5.36 GB)
Raid Devices : 3
Total Devices : 3
Persistence : Superblock is persistent
Update Time : Fri Mar 10 05:51:01 2017
State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 512K
Name : DanCentOS67:127
UUID : 1a86a744:b01bd085:ee05717d:8ba86e4a
Events : 38
Number Major Minor RaidDevice State
0 8 49 0 active sync /dev/sdd1
1 8 65 1 active sync /dev/sde1
3 8 50 2 active sync /dev/sdd2
[root@DanCentOS65 daniel]# mdadm --misc --detail /dev/md126
/dev/md126:
Version : 1.2
Creation Time : Thu Mar 9 14:43:46 2017
Raid Level : raid5
Array Size : 10465280 (9.98 GiB 10.72 GB)
Used Dev Size : 5232640 (4.99 GiB 5.36 GB)
Raid Devices : 3
Total Devices : 3
Persistence : Superblock is persistent
Update Time : Fri Mar 10 05:58:03 2017
State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 512K
Name : DanCentOS67:126
UUID : 72b40d3f:78790af8:d369e502:8547a8b1
Events : 41
Number Major Minor RaidDevice State
4 8 66 0 active sync /dev/sde2
1 8 82 1 active sync /dev/sdf2
3 8 81 2 active sync /dev/sdf1
重新扫描 Physical Volume：
[root@DanCentOS65 daniel]# pvscan
PV /dev/md127 VG VolGroup1 lvm2 [9.98 GiB / 0 free]
PV /dev/md126 VG VolGroup1 lvm2 [9.98 GiB / 0 free]
PV /dev/md125 VG VolGroup1 lvm2 [4.99 GiB / 0 free]
Total: 3 [24.94 GiB] / in use: 3 [24.94 GiB] / in no VG: 0 [0 ]
扫描 Logical Volume：
[root@DanCentOS65 daniel]# lvscan
ACTIVE '/dev/VolGroup1/LogicalVol1' [9.77 GiB] inherit
inactive '/dev/VolGroup1/LogicalVol2' [15.18 GiB] inherit
看到 Logical Volume 2 inactive了，重新激活这个 Logical Volume：
[root@DanCentOS65 daniel]# lvchange -a y /dev/VolGroup1/LogicalVol2
激活后再次查看状态：
[root@DanCentOS65 daniel]# lvscan
ACTIVE '/dev/VolGroup1/LogicalVol1' [9.77 GiB] inherit
ACTIVE '/dev/VolGroup1/LogicalVol2' [15.18 GiB] inherit
fdisk -l 查看发现可以识别出 Logical Volume 2了：
[root@DanCentOS65 daniel]# fdisk -l
……
Disk /dev/mapper/VolGroup1-LogicalVol1: 10.5 GB, 10485760000 bytes
255 heads, 63 sectors/track, 1274 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 524288 bytes / 1048576 bytes
Disk identifier: 0x00000000
Disk /dev/mapper/VolGroup1-LogicalVol2: 16.3 GB, 16294871040 bytes
255 heads, 63 sectors/track, 1981 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 524288 bytes / 1048576 bytes
Disk identifier: 0x00000000
将两个分区挂在到目录下：
[root@DanCentOS65 daniel]# mkdir /mnt/LV1
[root@DanCentOS65 daniel]# mkdir /mnt/LV2
[root@DanCentOS65 daniel]# mount /dev/mapper/VolGroup1-LogicalVol1 /mnt/LV1
[root@DanCentOS65 daniel]# mount /dev/mapper/VolGroup1-LogicalVol2 /mnt/LV2
进入目录中查看文件未丢失或损坏，将文档下载到本地后可以正常打开：
[root@DanCentOS65 daniel]# cd /mnt/LV2
[root@DanCentOS65 LV2]# ll
total 7508
-rw-r--r--. 1 root root 7670041 Jul 6 2016 Azure.pdf
drwx------ 2 root root 16384 Mar 9 15:02 lost+found
至此，迁移工作结束。
删除 LVM 环境：
最后来做一点破坏性工作，将整个环境拆解掉。
首先将两个分区卸载：
[root@DanCentOS65 daniel]# umount /dev/mapper/VolGroup1-LogicalVol1
[root@DanCentOS65 daniel]# umount /dev/mapper/VolGroup1-LogicalVol2
接着可以删除 Logical Volume：
[root@DanCentOS65 daniel]# lvremove -f /dev/mapper/VolGroup1-LogicalVol1
Logical volume "LogicalVol1" successfully removed
[root@DanCentOS65 daniel]# lvremove -f /dev/mapper/VolGroup1-LogicalVol2
Logical volume "LogicalVol2" successfully removed
删除 Volume Group：
[root@DanCentOS65 daniel]# vgremove VolGroup1
Volume group "VolGroup1" successfully removed
删除 Physical Volume：
[root@DanCentOS65 daniel]# pvremove /dev/md125 /dev/md126 /dev/md127
Labels on physical volume "/dev/md125" successfully wiped
Labels on physical volume "/dev/md126" successfully wiped
Labels on physical volume "/dev/md127" successfully wiped
停止 RAID 5 阵列：
[root@DanCentOS65 daniel]# mdadm --stop /dev/md125
mdadm: stopped /dev/md125
[root@DanCentOS65 daniel]# mdadm --stop /dev/md126
mdadm: stopped /dev/md126
[root@DanCentOS65 daniel]# mdadm --stop /dev/md127
mdadm: stopped /dev/md127
停止后发现已经没有 RAID 5 Device 了：
[root@DanCentOS65 daniel]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
unused devices: <none>
注：正常应该还执行下面两个命令完全删除，不过这里已经检测不到 md Device 了，所以就不需要了。
mdadm --remove /dev/md125
mdadm --zero-superblock /dev/sdg1 /dev/sdg2
