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
查看当前信息
[root@localhost ~]# qemu-img info /data/kvm_name.qcow2 //本身只有500G p_w_picpath: /data/kvm_name.qcow2 file format: qcow2 virtual size: 500G (536,870,912,000bytes) disk size: 500G cluster_size: 65536
修改信息 增加容量
[root@localhost ~]# qemu-img resize /data/kvm_name.qcow2 +100G //加100G Image resized.
查看修改后的信息
[root@localhost ~]# qemu-img info /data/kvm_name.qcow2 //查看已经+100G，登录虚拟机后fdisk -l还是500G p_w_picpath: /data/kvm_name.qcow2 file format: qcow2 virtual size: 600G (16106127360 bytes)
如果需要真正生效，需要destroy，之后start，把配置重新加载
[root@localhost ~]# virsh destroy kvm_name [root@localhost ~]# virsh start kvm_name
进入kvm
[root@localhost ~]# virsh console kvm_name
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100G
[root@localhost ~]# fdisk -l 磁盘 /dev/vda：644.2 GB, 644245094400 字节，1258291200 个扇区
2、但是磁盘挂载的空间并没有增加，依然是170G
[root@localhost ~]# df -h //查看可用磁盘总容量和使用容量 文件系统 容量 已用 可用 已用% 挂载点 /dev/mapper/centos-root 170G 170G 517M 100% / devtmpfs 16G 0 16G 0% /dev tmpfs 16G 0 16G 0% /dev/shm tmpfs 16G 9.3M 16G 1% /run tmpfs 16G 0 16G 0% /sys/fs/cgroup /dev/vda1 1014M 145M 870M 15% /boot /dev/mapper/centos-home 26G 307M 25G 2% /home tmpfs 3.2G 0 3.2G 0% /run/user/0
因已存在vda3 分区使用vda4
(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/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 Id System
/dev/vda1 * 3 1018 512000 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/vda2 1018 20806 9972736 8e Linux 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 Id System
/dev/vda1 * 3 1018 512000 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/vda2 1018 20806 9972736 8e Linux LVM
Partition 2 does not end on cylinder boundary.
/dev/vda3 20807 31207 5242104 83 Linux
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/vda4 加入到lvm里面去：
[root@localhost ~]# ls /dev/vda4 //如果没有这个分区，需要重启一下
[root@localhost ~]# reboot [root@localhost ~]# pvcreate /dev/vda4 //创建物理卷 Physical volume "/dev/vda4" successfully created
[root@localhost ~]# pvs //查看卷 PV VG Fmt Attr PSize PFree /dev/vda2 centos lvm2 a-- <79.00g 0 /dev/vda3 centos lvm2 a-- <120.00g 100.00m /dev/vda4 lvm2 --- 400.00g 400.00g
[root@localhost ~]# vgextend centos /dev/vda4 //centos虚拟卷扩展 ，vda4加入到VolGroup卷组 centos Volume group "centos" successfully extended
[root@localhost ~]# pvs PV VG Fmt Attr PSize PFree /dev/vda2 centos lvm2 a-- <79.00g 0 /dev/vda3 centos lvm2 a-- <120.00g 100.00m /dev/vda4 centos lvm2 a-- <400.00g <400.00g
此步骤是pvs的VG列较之前变的有值了
[root@localhost ~]# vgs //VFree中400G 如何把400G加入到root中？ VG #PV #LV #SN Attr VSize VFree centos 3 3 0 wz--n- <598.99g 400.09g
[root@localhost ~]# lvs //查看逻辑卷 LV VG Attr LSize Pool Origin Data% meta% Move Log Cpy%Sync Convert home centos -wi-ao---- <25.12g root centos -wi-ao---- 169.90g swap centos -wi-ao---- <3.88g
[root@localhost ~]# lvextend -l +100%FREE /dev/centos/root //扩展卷 centos 与 root 也和上方的“值对应关系”一致 Size of logical volume centos/root changed from 169.90 GiB (43495 extents) to <570.00 GiB (145919 extents). Logical volume centos/root successfully resized.
[root@localhost ~]# df -h # 当前容量未发生变化 文件系统 容量 已用 可用 已用% 挂载点 /dev/mapper/centos-root 170G 170G 379M 100% / devtmpfs 16G 0 16G 0% /dev tmpfs 16G 0 16G 0% /dev/shm tmpfs 16G 9.3M 16G 1% /run tmpfs 16G 0 16G 0% /sys/fs/cgroup /dev/vda1 1014M 145M 870M 15% /boot /dev/mapper/centos-home 26G 307M 25G 2% /home tmpfs 3.2G 0 3.2G 0% /run/user/0
[root@localhost ~]# resize2fs /dev/centos/root #如resize2fs执行失败则改为xfs_growfs resize2fs 1.41.12 (17-May-2010) Filesystem at /dev/centos/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.
[root@localhost ~]# df -h # 容量已发生变化 文件系统 容量 已用 可用 已用% 挂载点 /dev/mapper/centos-root 570G 170G 401G 30% / devtmpfs 16G 0 16G 0% /dev tmpfs 16G 0 16G 0% /dev/shm tmpfs 16G 9.3M 16G 1% /run tmpfs 16G 0 16G 0% /sys/fs/cgroup /dev/vda1 1014M 145M 870M 15% /boot /dev/mapper/centos-home 26G 307M 25G 2% /home tmpfs 3.2G 0 3.2G 0% /run/user/0
如果提示 This p_w_picpath 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/kvm_name.qcow2 5G关闭虚拟机： virsh destroy kvm_name编辑配置文件： virsh edit kvm_name
复制增加如下：注意是vdb，qcow2
开启虚拟机：virsh start kvm_name
进入虚拟机：virsh console kvm_name
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 0
mount -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 p_w_picpath 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。
转自：https://blog.csdn.net/weixin_35583709/article/details/116819328
