之前一篇 [use lvm]({% post_url 2013-12-12-use-lvm %}) 总结了lvm的pv/vg/lv创建使用等基本方法.
这里总结下lv的reduce/extend等方法.
基本环境: /dev/sda3, /dev/sda4 分别1G大小的pv
初始将/dev/sda3加入到vg:
$ vgcreate vg_data /dev/sda3
默认PE是4MB, 所以1G有255个PE
创建lv, 大小分配125个PE
$ lvcreate -l 125 -n lv_data vg_data
这里也可以通过百分比来创建, 如:
$ lvcreate -l 50%VG -n lv_data vg_data
当前的状态:
$ pvdisplay /dev/sda3
--- Physical volume ---
PV Name /dev/sda3
VG Name vg_data
PV Size 1.00 GiB / not usable 4.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 255
Free PE 130
Allocated PE 125
PV UUID 0ife1n-hdHA-m6gA-rjCE-uyPD-tzaS-LE8jKo
$ vgdisplay
--- Volume group ---
VG Name vg_data
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 0
Max PV 0
Cur PV 1
Act PV 1
VG Size 1020.00 MiB
PE Size 4.00 MiB
Total PE 255
Alloc PE / Size 125 / 500.00 MiB
Free PE / Size 130 / 520.00 MiB
VG UUID ZieGlO-7dJM-1qVh-zMjF-MugH-qC0a-nVGPOU
$ lvdisplay
--- Logical volume ---
LV Path /dev/vg_data/lv_data
LV Name lv_data
VG Name vg_data
LV UUID eM1pNB-v36r-26H4-yc9I-fFse-IlZQ-G2eJbx
LV Write Access read/write
LV Creation host, time gentoo-local, 2015-05-25 07:29:25 +0800
LV Status available
# open 0
LV Size 500.00 MiB
Current LE 125
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 254:0
显示lv大小500M, vg总大小1020M
格式化后挂载到/mnt/lvm下
$ df -lh
Filesystem Size Used Avail Use% Mounted on
...
/dev/mapper/vg_data-lv_data 485M 11M 449M 3% /mnt/lvm
扩容
使用lvresize扩容, 加100个PE:
$ lvresize -l +100 /dev/vg_data/lv_data
Extending logical volume lv_data to 900.00 MiB
Logical volume lv_data successfully resized
$ pvdisplay /dev/sda3
--- Physical volume ---
PV Name /dev/sda3
VG Name vg_data
PV Size 1.00 GiB / not usable 4.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 255
Free PE 30
Allocated PE 225
PV UUID 0ife1n-hdHA-m6gA-rjCE-uyPD-tzaS-LE8jKo
$ lvdisplay
--- Logical volume ---
LV Path /dev/vg_data/lv_data
LV Name lv_data
VG Name vg_data
LV UUID eM1pNB-v36r-26H4-yc9I-fFse-IlZQ-G2eJbx
LV Write Access read/write
LV Creation host, time gentoo-local, 2015-05-25 07:29:25 +0800
LV Status available
# open 1
LV Size 900.00 MiB
Current LE 225
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 254:0
$ df -h
Filesystem Size Used Avail Use% Mounted on
...
/dev/mapper/vg_data-lv_data 485M 11M 449M 3% /mnt/lvm
lvdisplay显示LV大小变了, 但是df看到实际还没变.
这里使用dumpe2fs可以看到文件系统block的使用情况:
$ dumpe2fs /dev/vg_data/lv_data
使用resize2fs来进行实际扩容, 加到700M:
$ resize2fs /dev/vg_data/lv_data 700M
resize2fs 1.42 (29-Nov-2011)
Filesystem at /dev/vg_data/lv_data is mounted on /mnt/lvm; on-line resizing required
old_desc_blocks = 2, new_desc_blocks = 3
The filesystem on /dev/vg_data/lv_data is now 716800 blocks long.
$ df -lh
Filesystem Size Used Avail Use% Mounted on
...
/dev/mapper/vg_data-lv_data 678M 11M 635M 2% /mnt/lvm
注意这里, resize2fs 可以进行在线(on-line)扩容.
缩容
缩容是扩容的逆过程, 操作大部分类似, 不过无法进行在线缩容, 且缩容要注意的就是剩余的空间是否能放下所有原来的数据, 以及数据迁移的问题.
一个使用场景: 现在/dev/sda3, /dev/sda4都加入到lv中了, 需要将/dev/sda3取下来, 只留下/dev/sda4
接着上面的操作, 来初始当前的环境, 把/dev/sda3剩余PE和/dev/sda4的所有PE都给LV扩容:
$ vgextend vg_data /dev/sda4
Volume group "vg_data" successfully extended
$ lvresize -l +285 /dev/vg_data/lv_data
Extending logical volume lv_data to 1.99 GiB
Logical volume lv_data successfully resized
$ resize2fs /dev/vg_data/lv_data # 不接size则默认使用所有剩余空间扩容
resize2fs 1.42 (29-Nov-2011)
Filesystem at /dev/vg_data/lv_data is mounted on /mnt/lvm; on-line resizing required
old_desc_blocks = 5, new_desc_blocks = 8
The filesystem on /dev/vg_data/lv_data is now 2088960 blocks long.
$ df -h
Filesystem Size Used Avail Use% Mounted on
...
/dev/mapper/vg_data-lv_data 2.0G 11M 1.9G 1% /mnt/lvm
创建一个300M的数据:
$ dd if=/dev/zero of=/mnt/lvm/a.block bs=1000000 count=300
/dev/sda3的PE是255个, 现在要将/dev/sda3移除, 先通过resize2fs进行实际容量缩小:
$ resize2fs /dev/vg_data/lv_data 1000M
resize2fs 1.42 (29-Nov-2011)
Filesystem at /dev/vg_data/lv_data is mounted on /mnt/lvm; on-line resizing required
resize2fs: On-line shrinking not supported
$ umount /mnt/lvm
$ resize2fs /dev/vg_data/lv_data 1000M
resize2fs 1.42 (29-Nov-2011)
Please run 'e2fsck -f /dev/vg_data/lv_data' first.
$ e2fsck -f /dev/vg_data/lv_data
e2fsck 1.42 (29-Nov-2011)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/vg_data/lv_data: 12/518160 files (0.0% non-contiguous), 369565/2088960 blocks
$ resize2fs /dev/vg_data/lv_data 1000M
resize2fs 1.42 (29-Nov-2011)
Resizing the filesystem on /dev/vg_data/lv_data to 1024000 (1k) blocks.
The filesystem on /dev/vg_data/lv_data is now 1024000 blocks long.
可以看到, resize2fs不能进行在线缩容, 且缩容前还需要e2fsck检查磁盘
重新挂载上:
$ mount /dev/vg_data/lv_data /mnt/lvm
$ df -lh
Filesystem Size Used Avail Use% Mounted on
...
/dev/mapper/vg_data-lv_data 969M 297M 630M 33% /mnt/lvm
lvresize减小LV容量:
$ lvresize -l -255 /dev/vg_data/lv_data
WARNING: Reducing active and open logical volume to 1020.00 MiB
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce lv_data? [y/n]: y
Reducing logical volume lv_data to 1020.00 MiB
Logical volume lv_data successfully resized
$ lvdisplay
--- Logical volume ---
LV Path /dev/vg_data/lv_data
LV Name lv_data
VG Name vg_data
LV UUID eM1pNB-v36r-26H4-yc9I-fFse-IlZQ-G2eJbx
LV Write Access read/write
LV Creation host, time gentoo-local, 2015-05-25 07:29:25 +0800
LV Status available
# open 1
LV Size 1020.00 MiB
Current LE 255
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 254:0
$ pvdisplay
--- Physical volume ---
PV Name /dev/sda3
VG Name vg_data
PV Size 1.00 GiB / not usable 4.00 MiB
Allocatable yes (but full)
PE Size 4.00 MiB
Total PE 255
Free PE 0
Allocated PE 255
PV UUID 0ife1n-hdHA-m6gA-rjCE-uyPD-tzaS-LE8jKo
--- Physical volume ---
PV Name /dev/sda4
VG Name vg_data
PV Size 1.00 GiB / not usable 4.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 255
Free PE 255
Allocated PE 0
PV UUID gp2cuI-9g7g-KPXk-jbVH-fKqC-3mV0-5jN7yV
因为/dev/sda4是后添加的, 这里减少LV空间, 释放的PE实际是/dev/sda4的PE
接着通过pvmove把/dev/sda3的PE移到/dev/sda4:
$ pvmove /dev/sda3 /dev/sda4
/dev/sda3: Moved: 1.6%
/dev/sda3: Moved: 100.0%
$ pvdisplay
--- Physical volume ---
PV Name /dev/sda3
VG Name vg_data
PV Size 1.00 GiB / not usable 4.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 255
Free PE 255
Allocated PE 0
PV UUID 0ife1n-hdHA-m6gA-rjCE-uyPD-tzaS-LE8jKo
--- Physical volume ---
PV Name /dev/sda4
VG Name vg_data
PV Size 1.00 GiB / not usable 4.00 MiB
Allocatable yes (but full)
PE Size 4.00 MiB
Total PE 255
Free PE 0
Allocated PE 255
PV UUID gp2cuI-9g7g-KPXk-jbVH-fKqC-3mV0-5jN7yV
然后进行一些收尾操作:
$ vgreduce vg_data /dev/sda3
Removed "/dev/sda3" from volume group "vg_data"
$ pvremove /dev/sda3
Labels on physical volume "/dev/sda3" successfully wiped
其它
pvdisplay -m可以看到哪些PE和LV/LE的对应关系