KVM虚拟磁盘扩容

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
[root@daixuan ~]# qemu-img info /data/daixuan1.qcow2 //本身只有9Gimage: /data/daixuan1.qcow2file format: qcow2virtual size: 10G (10737418240 bytes)disk size: 10Gcluster_size: 65536[root@daixuan ~]# qemu-img resize /data/daixuan1.qcow2 +5G //加5GImage resized.[root@daixuan ~]# qemu-img info /data/daixuan1.qcow2 //查看已经+5G，登录后fdisk -l还是10Gimage: /data/daixuan1.qcow2file format: qcow2virtual 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[root@daixuan ~]# virsh destroy daixuan1[root@daixuan ~]# virsh start daixuan1[root@daixuan ~]# virsh console daixuan1
fdisk -l 列出系统中所有的磁盘设备和分区表，这里磁盘设备容量已经增加5G[root@localhost ~]# fdisk -lDisk /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[root@localhost ~]# df -h //查看可用磁盘总容量和使用容量Filesystem Size Used Avail Use% Mounted on /dev/mapper/VolGroup-lv_root 8.3G 685M 7.2G 9% / tmpfs 246M 0 246M 0% /dev/shm/dev/vda1 477M 33M 419M 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：
[root@localhost ~]# fdisk /dev/vdaWARNING: 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): pDisk /dev/vda: 16.1 GB, 16106127360 bytes16 heads, 63 sectors/track, 31207 cylindersUnits = cylinders of 1008 * 512 = 516096 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x000dca27 Device Boot Start End Blocks Id System/dev/vda1 * 3 1018 512000 83 LinuxPartition 1 does not end on cylinder boundary./dev/vda2 1018 20806 9972736 8e Linux LVMPartition 2 does not end on cylinder boundary.
Command (m for help): nCommand action e extended p primary partition (1-4)pPartition number (1-4): 3First cylinder (1-31207, default 1): 20807Last cylinder, +cylinders or +size{K,M,G} (20807-31207, default 31207): 31207
Command (m for help): pDisk /dev/vda: 16.1 GB, 16106127360 bytes16 heads, 63 sectors/track, 31207 cylindersUnits = cylinders of 1008 * 512 = 516096 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x000dca27
Device Boot Start End Blocks Id System/dev/vda1 * 3 1018 512000 83 LinuxPartition 1 does not end on cylinder boundary./dev/vda2 1018 20806 9972736 8e Linux LVMPartition 2 does not end on cylinder boundary./dev/vda3 20807 31207 5242104 83 Linux
Command (m for help): wThe 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 atthe 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：
[root@localhost ~]# ls /dev/vda3 //如果没有这个分区，需要重启一下[root@localhost ~]# reboot[root@localhost ~]# pvcreate /dev/vda3 //创建物理卷 Physical volume "/dev/vda3" successfully created
[root@localhost ~]# pvs //查看卷 PV VG Fmt Attr PSize PFree /dev/vda2 VolGroup lvm2 a-- 9.51g 0 /dev/vda3 lvm2 --- 5.00g 5.00g
[root@localhost ~]# vgextend VolGroup /dev/vda3 //VolGroup虚拟卷扩展，vda3加入到Vol Volume group "VolGroup" successfully extended
[root@localhost ~]# pvs PV VG Fmt Attr PSize PFree /dev/vda2 VolGroup lvm2 a-- 9.51g 0 /dev/vda3 VolGroup lvm2 a-- 5.00g 0
[root@localhost ~]# vgs //VFree中5G VG #PV #LV #SN Attr VSize VFree VolGroup 2 2 0 wz--n- 14.50g 5.00g 如何把5G加入到lv_root中？
[root@localhost ~]# lvs //查看逻辑卷 LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert lv_root VolGroup -wi-ao---- 8.54g lv_swap VolGroup -wi-ao---- 992.00m
[root@localhost ~]# lvextend -l +100%FREE /dev/VolGroup/lv_root //扩展卷 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
[root@localhost ~]# df -hFilesystem Size Used Avail Use% Mounted on/dev/mapper/VolGroup-lv_root 8.3G 685M 7.2G 9% /tmpfs 246M 0 246M 0% /dev/shm/dev/vda1 477M 33M 419M 8% /boot
[root@localhost ~]# resize2fs /dev/VolGroup/lv_root resize2fs 1.41.12 (17-May-2010)Filesystem at /dev/VolGroup/lv_root is mounted on /; on-line resizing requiredold desc_blocks = 1, new_desc_blocks = 1Performing 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.
[root@localhost ~]# df -hFilesystem Size Used Avail Use% Mounted on/dev/mapper/VolGroup-lv_root 14G 687M 12G 6% /tmpfs 246M 0 246M 0% /dev/shm/dev/vda1 477M 33M 419M 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
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 /mnt ext4 defaults 0 0mount -a 然后mnt就可以使用了[root@localhost ~]# cd /mnt[root@localhost 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，测试成功，这里省略步骤

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。

本文出自 “梅花香自苦寒来！” 博客，请务必保留此出处http://daixuan.blog.51cto.com/5426657/1743047