就一般生產系統而已，操作系統層面都要進行備份，而最常見的操作系統備份方式之一就是做鏡像（mirror），而實踐過程中，往往是把rootvg這個卷組做鏡像操作。查看rootvg是否已經進行鏡像方法：

1） lsvg –o

2）lsvg –l rootvg

# lsvg -l rootvg rootvg: LV NAME TYPE LPs PPs PVs LV STATE MOUNT POINT hd5 boot 1 2 2 closed/syncd N/A hd6 paging 16 32 2 open/syncd N/A hd8 jfs2log 1 2 2 open/syncd N/A hd4 jfs2 12 24 2 open/syncd / hd2 jfs2 10 20 2 open/syncd /usr hd9var jfs2 6 12 2 open/syncd /var hd3 jfs2 6 12 2 open/syncd /tmp hd1 jfs2 400 800 2 open/syncd /home hd10opt jfs2 1 2 2 open/syncd /opt hd11admin jfs2 1 2 2 open/syncd /admin fwdump jfs2 2 4 2 open/syncd /var/adm/ras/platform lg_dumplv sysdump 3 3 1 open/syncd N/A livedump jfs2 1 2 2 open/syncd /var/adm/ras/livedump

如上圖所示，LPs與PPs的比例是1:2證明rootvg已經做了鏡像，即做了一份rootvg的副本，便于操作系統層面出現問題時，及時還原。如果LPs與PPs的比例是1:1這表名是沒有做rootvg鏡像的。而且PVs都是2，證明是兩塊物理磁盤做的鏡像操作。

# lsvg rootvg VOLUME GROUP: rootvg VG IDENTIFIER: 00f9150300004c0000000145634ba48d VG STATE: active PP SIZE: 1024 megabyte(s) VG PERMISSION: read/write TOTAL PPs: 1116 (1142784 megabytes) MAX LVs: 256 FREE PPs: 199 (203776 megabytes) LVs: 13 USED PPs: 917 (939008 megabytes) OPEN LVs: 12 QUORUM: 1 (Disabled) TOTAL PVs: 2 VG DESCRipTORS: 3 STALE PVs: 0 STALE PPs: 0 ACTIVE PVs: 2 AUTO ON: yes MAX PPs per VG: 32512 MAX PPs per PV: 1016 MAX PVs: 32 LTG size (Dynamic): 1024 kilobyte(s) AUTO SYNC: no HOT SPARE: no BB POLICY: relocatable PV RESTRICTION: none INFINITE RETRY: no

rootvg大小為1142784MB，但實際可用空間只是這個數據的一般，即：571392MB，因為你做了一份鏡像操作。

# lspv hdisk0 00f91503634b9132 rootvg active hdisk1 00f91503639b9dbf rootvg active hdisk2 00f91503747466fd datavg active hdisk3 00f915037474679d datavg active hdisk4 00f91503ac90ba5d datavg active hdisk5 00f91503bbd0aea1 datavg active hdisk6 none None

可見，rootvg是由hisk0和hdisk1兩個磁盤組成。

　　使用命令為mirrorvg。mirrorvg命令將給已存在某個卷組上的邏輯卷最鏡像操作。與此相同功能的命令為mklvcopy。

語法：

Purpose

Mirrors all the logical volumes that exist on a given volume group.

Syntax

mirrorvg [ -S | -s ] [ -Q ] [ -c copies] [ -m ] [ -p copyn=mirrorpool ] volumegroup [ physicalvolume ... ]

-c copies Specifies the minimum number of copies that each logical volume must have after the mirrorvg command has finished executing. It may be possible, through the independent use of mklvcopy, that some logical volumes may have more than the minimum number specified after the mirrorvg command has executed. Minimum value is 2 and 3 is the maximum value. A value of 1 is ignored.

-m exact map Allows mirroring of logical volumes in the exact physical partition order that the original copy is ordered. This option requires you to specify a PhysicalVolume(s) where the exact map copy should be placed. If the space is insufficient for an exact mapping, then the command will fail. You should add new drives or pick a different set of drives that will satisfy an exact logical volume mapping of the entire volume group. The designated disks must be equal to or exceed the size of the drives which are to be exactly mirrored, regardless of if the entire disk is used. Also, if any logical volume to be mirrored is already mirrored, this command will fail.

-S Background Sync Returns the mirrorvg command immediately and starts a background syncvg of the volume group. With this option, it is not obvious when the mirrors have completely finished their synchronization. However, as portions of the mirrors become synchronized, they are immediately used by the Operating system in mirror usage.

-s Disable Sync Returns the mirrorvg command immediately without performing any type of mirror synchronization. If this option is used, the mirror may exist for a logical volume but is not used by the operating system until it has been synchronized with the syncvg command.

假如我們將rootvg的鏡像到hdisk1磁盤上，命令如下：

mirrorvg –S -c 2 rootvg hsisk0 hdisk1

操作完成后，還要執行以下兩個命令：

(1) bosboot The bosboot command is required to customize the bootrec of the newly mirrored drive.

The bosboot command creates a boot file (boot image) from a RAM (Random access Memory) disk file system and a kernel. This boot image is transferred to a particular media that the ROS boot code recognizes. When the machine is powered on or rebooted, the ROS boot code loads the boot image from the media into memory. ROS then transfers control to the loaded images kernel.

(2) bootlist The bootlist command needs to be performed to instruct the system which disk and order you PRefer the mirrored boot process to start.

操作如下：

(1)執行bosboot命令

bosboot -ad /dev/hdisk0 bosboot -ad /dev/hdisk1

(2) 執行bootlist命令： 設置系統的引導順序

bootlist -m normal hdisk0 hdisk1 cd0

(3) 查看引導熟悉結果

bootlist -o -m normal

當我們發現，在鏡像卷組中的一塊盤有問題時，需要使用一塊新磁盤來頂替這塊有問題的磁盤。操作方法如下：

(1) 取消hdisk7盤上的鏡像

unmirrorvg workvg hdisk7

(2) 從卷組中刪除hdisk7磁盤 reducevg workvg hdisk7

(3) 系統層面刪除hdisk7 rmdev -l hdisk7 –d

(4) 識別新盤

cfgmgr –v

(5) 重命名磁盤

需要將新識別的磁盤為hdisk7，關于hdiskX的名字是存在操作系統底層的ODM數據庫里的，ODM數據庫包含了所有PV、VG和LV的配置信息，這些信息與VGDA中的信息互為鏡象，ODM數據也和LV控制塊中的信息相互鏡象。因此需要將原先的hdisk盤從系統層面刪除，然后再去重新掃盤，讓系統識別出新掃描到的磁盤名稱與之前的名稱是一致的。

查看物理磁盤命令：lspv

給磁盤一個ID編號：chdev –l hdisk7 –a pv=yes

(6) 將磁盤添加到卷組中

extendvg workvg hdisk7

(7) 查看workvg鏡像情況 mirrorvg workvg

命令：unmirrorvg

Purpose

Removes the mirrors that exist on volume groups or specified disks. This command only applies to AIX 4.2.1 or later.

Syntax

unmirrorvg [ -c Copies ] VolumeGroup [ PhysicalVolume .. . ]

例如：取消workvg卷組鏡像，留有一份副本

命令：unmirrorvg -c 1 workvg

　　When unmirrorvg workvg hdisk7 is run, hdisk7 will be the remaining drive in the volume group. This drive is not actually removed from the volume group. You must run the migratepv command to move the data from the disk that is to be removed from the system to disk hdisk7.

migratepv命令：

Purpose

Moves allocated physical partitions from one physical volume to one or more other physical volumes.

Syntax

migratepv [ -i ] [ -l LogicalVolume ] SourcePhysicalVolume DestinationPhysicalVolume...

Description

The migratepv command moves allocated physical partitions and the data they contain from the SourcePhysicalVolume to one or more other physical volumes. To limit the transfer to specific physical volumes, use the names of one or more physical volumes in the DestinationPhysicalVolume parameter; otherwise, all the physical volumes in the volume group are available for the transfer. All physical volumes must be within the same volume group. The specified source physical volume cannot be included in the list of DestinationPhysicalVolume parameters.