怎样从VG中移走PV ?
https:// svn.wso2.org //repos // wso2 // tags // wsas // java // 3.2.1 //
例如将/dev/sdb1从逻辑卷中移出:
linux-0eob:/ # pvmove /dev/sdb1
/dev/sdb1: Moved: 100.0%

linux-0eob:/ # pvscan
? PV /dev/sdb1?? VG vg0?? lvm2 [52.00 MB / 52.00 MB free]
? PV /dev/sdb2?? VG vg0?? lvm2 [52.00 MB / 32.00 MB free]
? PV /dev/sdb3?? VG vg0?? lvm2 [52.00 MB / 52.00 MB free]
? Total: 3 [156.00 MB] / in use: 3 [156.00 MB] / in no VG: 0 [0?? ]
从vg0 中移走pv
linux-0eob:/ # vgreduce vg0 /dev/sdb1

? Removed "/dev/sdb1" from volume group "vg0"
再一次查看:
linux-0eob:/ # pvscan
? PV /dev/sdb2?? VG vg0???????????? lvm2 [52.00 MB / 32.00 MB free]
? PV /dev/sdb3?? VG vg0???????????? lvm2 [52.00 MB / 52.00 MB free]
? PV /dev/sdb1????????????????????? lvm2 [54.88 MB]
? Total: 3 [158.88 MB] / in use: 2 [104.00 MB] / in no VG: 1 [54.88 MB]
这样/dev/sdb1就变成自由分区了

怎样指定vg中逻辑块的大小 ?
我们可以使用vgcreate的-s选项指定逻辑块大小,这样可以支持更大的逻辑卷
linux-0eob:/ # vgcreate vg1 -s 8M /dev/sdb1
? Volume group "vg1" successfully created
linux-0eob:/ # vgdisplay vg1
? --- Volume group ---
? VG Name?????????????? vg1
? System ID????????????
? Format??????????????? lvm2
? Metadata Areas??????? 1
? Metadata Sequence No? 1
? VG Access???????????? read/write
? VG Status???????????? resizable
? MAX LV??????????????? 0
? Cur LV??????????????? 0
? Open LV?????????????? 0
? Max PV??????????????? 0
? Cur PV??????????????? 1
? Act PV??????????????? 1
? VG Size?????????????? 48.00 MB
? PE Size?????????????? 8.00 MB
? Total PE????????????? 6
? Alloc PE / Size?????? 0 / 0??
? Free? PE / Size?????? 6 / 48.00 MB
? VG UUID?????????????? UWko2s-q9Qp-ybSZ-ZHJr-1FHl-R60q-8jzaR5

在vg1上创建逻辑卷
linux-0eob:/ # lvcreate -n lvdata2 -l 2 vg1
? Logical volume "lvdata2" created
linux-0eob:/ # lvdisplay
? --- Logical volume ---
? LV Name??????????????? /dev/vg0/lvdata
? VG Name??????????????? vg0
? LV UUID??????????????? tYWFX0-Msor-q6I3-dZjE-W06M-UKyj-McRdpP
? LV Write Access??????? read/write
? LV Status????????????? available
? # open???????????????? 1
? LV Size??????????????? 20.00 MB
? Current LE???????????? 5
? Segments?????????????? 1
? Allocation???????????? inherit
? Read ahead sectors???? auto
? - currently set to???? 256
? Block device?????????? 253:0
??
? --- Logical volume ---
? LV Name??????????????? /dev/vg1/lvdata2
? VG Name??????????????? vg1
? LV UUID??????????????? U2y1YP-uHOb-dKh3-pZTP-LFXJ-mOUm-hFZKzZ
? LV Write Access??????? read/write
? LV Status????????????? available
? # open???????????????? 0
? LV Size??????????????? 16.00 MB
? Current LE???????????? 2
? Segments?????????????? 1
? Allocation???????????? inherit
? Read ahead sectors???? auto
? - currently set to???? 256
? Block device?????????? 253:1
??
lvcreate 强大的功能还有哪些 ?

-s 选项可以备份lv中的数据,--snapshots;可以实时捕捉数据的变化.
??? 但是这种方式只能在负载不高的情形下进行.
linux-0eob:/ # lvcreate -n snap -s -l 4 /dev/vg1/lvdata2
? Logical volume "snap" created
这样/dev/vg1/lvdata2 中的内容会与 /dev/vg1/snap下的数据是实时同步的

如何转换逻辑卷的状态 ?
linux-0eob:/ # lvscan
? ACTIVE??????????? '/dev/vg0/lvdata' [20.00 MB] inherit
? ACTIVE?? Original '/dev/vg1/lvdata2' [16.00 MB] inherit
? ACTIVE?? Snapshot '/dev/vg1/snap' [32.00 MB] inherit
linux-0eob:/ # vgchange -an vg0
? Can't deactivate volume group "vg0" with 1 open logical volume(s)
linux-0eob:/ # vgchange -an vg1
? 0 logical volume(s) in volume group "vg1" now active
linux-0eob:/ # lvscan
? ACTIVE??????????? '/dev/vg0/lvdata' [20.00 MB] inherit
? inactive Original '/dev/vg1/lvdata2' [16.00 MB] inherit
? inactive Snapshot '/dev/vg1/snap' [32.00 MB] inherit

linux-0eob:/ # vgchange -ay vg1
? 1 logical volume(s) in volume group "vg1" now active
linux-0eob:/ # lvscan
? ACTIVE??????????? '/dev/vg0/lvdata