KVM虚拟磁盘扩容
虚拟磁盘磁盘扩容1、磁盘扩容分为raw和qcow2两种扩容方式，命令相同，区别是后缀名
# qemu-img info /data/daixuan1.qcow2 //本身只有9G
image: /data/daixuan1.qcow2
file format: qcow2
virtual size: 10G (10737418240 bytes)
disk size: 10G
cluster_size: 65536
# qemu-img resize /data/daixuan1.qcow2 +5G//加5G
Image resized.
# qemu-img info /data/daixuan1.qcow2//查看已经+5G，登录fdisk -l还是10G
image: /data/daixuan1.qcow2
file format: qcow2
virtual size: 15G (16106127360 bytes)
如果需要真正生效，需要destroy，之后start，把配置重新加载
# virsh destroy daixuan1
# virsh start daixuan1
# virsh console daixuan1
fdisk -l 查看已经磁盘分区已经增加
# fdisk -l
Disk /dev/vda: 16.1 GB, 16106127360 bytes
2、但是磁盘挂载的空间并没有增加，依然是8.3G
# df -h
FilesystemSizeUsed Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root 8.3G685M7.2G 9% /
tmpfs 246M 0246M 0% /dev/shm
/dev/vda1 477M 33M419M 8% /boot
（1）因为新增加的空间还没有划分使用，所以要继续分区：
# fdisk /dev/vda
# fdisk /dev/vda
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): p
Disk /dev/vda: 16.1 GB, 16106127360 bytes
16 heads, 63 sectors/track, 31207 cylinders
Units = cylinders of 1008 * 512 = 516096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000dca27
Device Boot Start End Blocks IdSystem
/dev/vda1 * 3 1018 512000 83Linux
Partition 1 does not end on cylinder boundary.
/dev/vda2 1018 20806 9972736 8eLinux LVM
Partition 2 does not end on cylinder boundary.
Command (m for help): n
Command action
e extended
p primary partition (1-4)
3
Invalid partition number for type `3'
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 3
First cylinder (1-31207, default 1): 20807
Last cylinder, +cylinders or +size{K,M,G} (20807-31207, default 31207):
#
# fdisk -l
Disk /dev/vda: 16.1 GB, 16106127360 bytes
16 heads, 63 sectors/track, 31207 cylinders
Units = cylinders of 1008 * 512 = 516096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000dca27
Device Boot Start End Blocks IdSystem
/dev/vda1 * 3 1018 512000 83Linux
Partition 1 does not end on cylinder boundary.
/dev/vda2 1018 20806 9972736 8eLinux LVM
Partition 2 does not end on cylinder boundary.
Disk /dev/mapper/VolGroup-lv_root: 9168 MB, 9168748544 bytes
255 heads, 63 sectors/track, 1114 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: 0x00000000
Disk /dev/mapper/VolGroup-lv_swap: 1040 MB, 1040187392 bytes
255 heads, 63 sectors/track, 126 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: 0x00000000
# fdisk /dev/vda
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): p
Disk /dev/vda: 16.1 GB, 16106127360 bytes
16 heads, 63 sectors/track, 31207 cylinders
Units = cylinders of 1008 * 512 = 516096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000dca27
Device Boot Start End Blocks IdSystem
/dev/vda1 * 3 1018 512000 83Linux
Partition 1 does not end on cylinder boundary.
/dev/vda2 1018 20806 9972736 8eLinux LVM
Partition 2 does not end on cylinder boundary.
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 3
First cylinder (1-31207, default 1): 20807
Last cylinder, +cylinders or +size{K,M,G} (20807-31207, default 31207): 31207
Command (m for help): p
Disk /dev/vda: 16.1 GB, 16106127360 bytes
16 heads, 63 sectors/track, 31207 cylinders
Units = cylinders of 1008 * 512 = 516096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000dca27
Device Boot Start End Blocks IdSystem
/dev/vda1 * 3 1018 512000 83Linux
Partition 1 does not end on cylinder boundary.
/dev/vda2 1018 20806 9972736 8eLinux LVM
Partition 2 does not end on cylinder boundary.
/dev/vda3 20807 31207 5242104 83Linux
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.
（2）然后再把这个/dev/vda3 加入到lvm里面去：
# ls /dev/vda3 //如果没有这个分区，需要重启一下
# reboot
# pvcreate /dev/vda3//创建物理卷
Physical volume "/dev/vda3" successfully created
# pvs //查看卷
PV VG FmtAttr PSize PFree
/dev/vda2VolGroup lvm2 a--9.51g0
/dev/vda3 lvm2 ---5.00g5.00g
# vgextend VolGroup /dev/vda3//VolGroup虚拟卷扩展，加入到Vol
Volume group "VolGroup" successfully extended
# pvs
PV VG FmtAttr PSize PFree
/dev/vda2VolGroup lvm2 a--9.51g 0
/dev/vda3VolGroup lvm2 a--5.00g 0
# vgs
VG #PV #LV #SN Attr VSizeVFree
VolGroup 2 2 0 wz--n- 14.50g 5.00g
如何把5G加入到lv_root中？
# lvs //查看逻辑卷
LV VGAttr LSize Pool Origin Data%Meta%Move Log Cpy%Sync Convert
lv_root VolGroup -wi-ao---- 8.54g
lv_swap VolGroup -wi-ao---- 992.00m
# lvextend -l +100%FREE /dev/VolGroup/lv_root
Size of logical volume VolGroup/lv_root changed from 8.54 GiB (2186 extents) to 13.54 GiB (3465 extents).
Logical volume lv_root successfully resized
# df -h
Filesystem SizeUsed Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root 8.3G685M7.2G 9% /
tmpfs 246M 0246M 0% /dev/shm
/dev/vda1 477M 33M419M 8% /boot
# resize2fs /dev/VolGroup/lv_root
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/VolGroup/lv_root is mounted on /; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 1
Performing an on-line resize of /dev/VolGroup/lv_root to 3548160 (4k) blocks.
The filesystem on /dev/VolGroup/lv_root is now 3548160 blocks long.
# df -h
Filesystem SizeUsed Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root 14G 687M 12G 6% /
tmpfs 246M 0246M 0% /dev/shm
/dev/vda1 477M 33M419M 8% /boot
如果提示 This image format does not support resize, 检查一下你qemu-img create的时候，是否有加 preallocation=metadata 选项，如果有，就不能resize了。
（3）另外，如果是增加磁盘，思路是
创建磁盘： qemu-img create -f qcow2/data/daixuan1_2.qcow2 5G
关闭虚拟机： virsh destroy daixuan1
编辑配置文件： virsh edit daixuan1
复制增加如下：注意是vdb，qcow2
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<disk type='file' device='disk'>
<driver name='qemu' type='qcow2' cache='none'/>
<source file='/data/daixuan1_2.qcow2'/>
<target dev='vdb' bus='virtio'/>
</disk>
开启虚拟机：virsh start daixuan1
进入虚拟机：virsh console daixuan1
分区： fdisk /dev/vdb
格式化：mkfs.ext4 /dev/vdb
挂载：vim /etc/fstab，添加一行：/dev/vdb/mntext4 defaults 0 0
mount -a 然后mnt就可以使用了
# cd /mnt
# touch 23.txt
当然也可以按照上面的思路把 /dev/vdb 加入到 lvm里面去
注： raw格式
步骤基本上和qcow2一样。如果提示 This image format does not support resize, 检查一下你qemu-img create的时候，是否有加preallocation=metadata 选项，如果有，就不能resize了。
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