# 七：如何在线添加/更改虚拟磁盘 > 本文将演示如何添加虚拟磁盘活LUN到KVM guest虚拟机，以及如何在线更改现有虚拟磁盘大小。整个操作无须停止guest操作系统。KVM支持物理LUN映射和虚拟磁盘映射到虚拟机。要映射虚拟磁盘，需要使用`qemu-img`命令来创建虚拟磁盘映像，而磁盘格式或者是`img`或者是`qcow2`。当然，你还是使用`dd`命令创建一个"无空隙"磁盘映像。 ## 映射SAN或SCSI磁盘到KVM虚拟机 * 使用root账号登录到KVM Hypervisor主机（物理服务器） * 这里假设我们在hypervisor节点从SAN存储获得了"`/dev/sdb`" LUN * 使用`virsh`命令列出运行的虚拟机 ``` [root@UA-HA ~]# virsh list Id Name State ---------------------------------------------------- 32 UAKVM2 running [root@UA-HA ~]# ``` * 检查UAKVM2虚拟机的设备映射 ``` [root@UA-HA ~]# virsh domblklist UAKVM2 --details Type Device Target Source ------------------------------------------------ file disk vda /var/lib/libvirt/images/UAKVM2.qcow2 block cdrom hda - [root@UA-HA ~]# ``` * 将LUN连接到`UAKVM2`虚拟机作为`vdb`设备 ``` [root@UA-HA ~]# virsh attach-disk UAKVM2 --source /dev/sdb --target vdb --persistent Disk attached successfully [root@UA-HA ~]# ``` * 检查完成的工作 ``` [root@UA-HA ~]# virsh domblklist UAKVM2 --details Type Device Target Source ------------------------------------------------ file disk vda /var/lib/libvirt/images/UAKVM2.qcow2 block disk vdb /dev/sdb block cdrom hda - [root@UA-HA ~]# ``` * 登录到`UAKVM2` KVM虚拟机中查看新添加的磁盘 ``` [root@UA-KVM1 ~]# fdisk -l /dev/vdb Disk /dev/vdb: 536 MB, 536870912 bytes, 1048576 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes [root@UA-KVM1 ~]# ``` 以上已经成功在线将SAN LUN映射到KVM虚拟机的`/dev/sdb` ## 添加新虚拟磁盘到KVM Guests 要映射一个虚拟磁盘到KVM虚拟机需要以下步骤： * 使用`qemu-img`命令创建一个新的虚拟磁盘 * 连接虚拟磁盘到guest domain * 登录到`UAKVM2`虚拟机内部检查连接的虚拟磁盘 ``` [root@UA-KVM1 ~]# fdisk -l |grep vd |grep -v Linux Disk /dev/vda: 4294 MB, 4294967296 bytes, 8388608 sectors Disk /dev/vdb: 536 MB, 536870912 bytes, 1048576 sectors [root@UA-KVM1 ~]# ``` * 登录到KVM Hypervisor主机（物理服务器） * 使用`qemu-img`命令创建一个新的虚拟磁盘 ``` [root@UA-HA images]# cd /var/lib/libvirt/images [root@UA-HA images]# qemu-img create -f qcow2 UAKVM2.disk2.qcow2 1G Formatting 'UAKVM2.disk2.qcow2', fmt=qcow2 size=1073741824 encryption=off cluster_size=65536 lazy_refcounts=off [root@UA-HA images]# ``` 注意：所有环境中的存储池路径将不同 也可以使用以下方式创建虚拟磁盘，即raw格式： ``` [root@UA-HA images]# qemu-img create -f raw UAKVM2.disk3.img 256M Formatting 'UAKVM2.disk3.img', fmt=raw size=268435456 [root@UA-HA images]# ``` 或者创建预分配存储磁盘（预分配存储可以获得更好的性能） ``` [root@UA-HA images]# dd if=/dev/zero of=UAKVM2.disk4.img bs=1M count=1000 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 14.6078 s, 71.8 MB/s [root@UA-HA images]# ``` 检查存储池中的虚拟磁盘大小 ``` [root@UA-HA images]# du -sh UAKVM2.disk* 196K UAKVM2.disk2.qcow2 --- qcow2 formatted virtual disk file (thin) 0 UAKVM2.disk3.img --- raw formatted virtual disk file (thin) 1000M UAKVM2.disk4.img --- raw formatted virtual disk file using dd command. [root@UA-HA images]# ``` * 将虚拟磁盘添加到KVM虚拟机 ``` [root@UA-HA images]# virsh attach-disk UAKVM2 --source /var/lib/libvirt/images/UAKVM2.disk2.qcow2 --target vdc --persistent Disk attached successfully [root@UA-HA images]# ``` * 验证工作 ``` [root@UA-HA images]# virsh domblklist UAKVM2 --details Type Device Target Source ------------------------------------------------ file disk vda /var/lib/libvirt/images/UAKVM2.qcow2 block disk vdb /dev/sdb file disk vdc /var/lib/libvirt/images/UAKVM2.disk2.qcow2 block cdrom hda - [root@UA-HA images]# ``` * 登录到虚拟机（`UAKVM2`）检查新添加的磁盘 ``` [root@UA-KVM1 ~]# fdisk -l /dev/vdc Disk /dev/vdc: 1073 MB, 1073741824 bytes, 2097152 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes [root@UA-KVM1 ~]# ``` 以上我们成功地在线添加了KVM虚拟机的虚拟磁盘 ## 在KVM中调整虚拟磁盘 * 登录到Guest VM(`UAKVM2`)检查磁盘 ``` [root@UA-KVM1 ~]# df -h /orastage Filesystem Size Used Avail Use% Mounted on /dev/vdc 1014M 33M 982M 4% /orastage [root@UA-KVM1 ~]# mount -v |grep /orastage /dev/vdc on /orastage type xfs (rw,relatime,attr2,inode64,noquota) [root@UA-KVM1 ~]# [root@UA-KVM1 ~]# fdisk -l /dev/vdc Disk /dev/vdc: 1073 MB, 1073741824 bytes, 2097152 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes [root@UA-KVM1 ~]# ``` * 登录到KVM Hypervisor主机（物理服务器） * 检查已经映射到KVM虚拟机的虚拟磁盘 ``` [root@UA-HA ~]# virsh domblklist UAKVM2 --details Type Device Target Source ------------------------------------------------ file disk vda /var/lib/libvirt/images/UAKVM2.qcow2 block disk vdb /dev/sdb file disk vdc /var/lib/libvirt/images/UAKVM2.disk2.qcow2 block cdrom hda - [root@UA-HA ~]# ``` * 刷新KVM存储池 ``` [root@UA-HA ~]# virsh pool-list Name State Autostart ------------------------------------------- default active yes [root@UA-HA ~]# [root@UA-HA ~]# virsh pool-refresh default Pool default refreshed [root@UA-HA ~]# ``` * 使用`virsh vol-list`命令列出虚拟磁盘（`vdc = UAKVM2.disk2.qcow2`） ``` [root@UA-HA ~]# virsh vol-list default Name Path ------------------------------------------------------------------------------ UAKVM2.disk2.qcow2 /var/lib/libvirt/images/UAKVM2.disk2.qcow2 UAKVM2.disk3.img /var/lib/libvirt/images/UAKVM2.disk3.img UAKVM2.disk4.img /var/lib/libvirt/images/UAKVM2.disk4.img UAKVM2.qcow2 /var/lib/libvirt/images/UAKVM2.qcow2 [root@UA-HA ~]# ``` * 使用`qemu-monitor`列出`UAKVM2`域分配到块设备 ``` [root@UA-HA ~]# virsh qemu-monitor-command UAKVM2 --hmp "info block" drive-virtio-disk0: removable=0 io-status=ok file=/var/lib/libvirt/images/UAKVM2.qcow2 ro=0 drv=qcow2 encrypted=0 bps=0 bps_rd=0 bps_wr=0 iops=0 iops_rd=0 iops_wr=0 drive-virtio-disk1: removable=0 io-status=ok file=/dev/sdb ro=0 drv=raw encrypted=0 bps=0 bps_rd=0 bps_wr=0 iops=0 iops_rd=0 iops_wr=0 drive-virtio-disk2: removable=0 io-status=ok file=/var/lib/libvirt/images/UAKVM2.disk2.qcow2 ro=0 drv=raw encrypted=0 bps=0 bps_rd=0 bps_wr=0 iops=0 iops_rd=0 iops_wr=0 drive-ide0-0-0: removable=1 locked=0 tray-open=0 io-status=ok [not inserted] [root@UA-HA ~]# ``` 上述命令输出显示`UAKVM2.disk2.qcow2`被影射到`drive-virtio-disk2` * 增加虚拟磁盘大小（注意：千万不要缩小磁盘） ``` [root@UA-HA images]# virsh qemu-monitor-command UAKVM2 --hmp "block_resize drive-virtio-disk2 2G" [root@UA-HA images]# ``` * 登录到KVM虚拟机`UAKVM2`然后检查`vdc`磁盘大小 ``` [root@UA-KVM1 ~]# fdisk -l /dev/vdc Disk /dev/vdc: 2147 MB, 2147483648 bytes, 4194304 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes [root@UA-KVM1 ~]# ``` * 扩展文件系统，这里使用的文件系统是XFS ``` [root@UA-KVM1 ~]# df -h /orastage Filesystem Size Used Avail Use% Mounted on /dev/vdc 1014M 33M 982M 4% /orastage [root@UA-KVM1 ~]# mount -v |grep /orastage /dev/vdc on /orastage type xfs (rw,relatime,attr2,inode64,noquota) [root@UA-KVM1 ~]# [root@UA-KVM1 ~]# xfs_growfs /orastage/ meta-data=/dev/vdc isize=256 agcount=4, agsize=65536 blks = sectsz=512 attr=2, projid32bit=1 = crc=0 finobt=0 data = bsize=4096 blocks=262144, imaxpct=25 = sunit=0 swidth=0 blks naming =version 2 bsize=4096 ascii-ci=0 ftype=0 log =internal bsize=4096 blocks=2560, version=2 = sectsz=512 sunit=0 blks, lazy-count=1 realtime =none extsz=4096 blocks=0, rtextents=0 data blocks changed from 262144 to 1310720 [root@UA-KVM1 ~]# [root@UA-KVM1 ~]# df -h /orastage/ Filesystem Size Used Avail Use% Mounted on /dev/vdc 2.0G 33M 2.0G 1% /orastage [root@UA-KVM1 ~]# ``` 以上成功增加了虚拟机磁盘大小 ## 系列教程编译 本系列教程根据 [UnixArena Linux KVM](http://www.unixarena.com/category/redhat-linux/linux-kvm) 系列教程编译，共分以下文章： * [一：基于内核的虚拟机（KVM）概览](https://github.com/huataihuang/cloud-atlas-draft/tree/6f3204fffc11cf006abd394631e2598d98b415c3/virtual/kvm/startup/kernel_based_virtual_machine_kvm_overview/README.md) * [二：Redhat企业Linux安装KVM](https://github.com/huataihuang/cloud-atlas-draft/tree/6f3204fffc11cf006abd394631e2598d98b415c3/virtual/kvm/startup/redhat_enterprise_linux_kvm_installation/README.md) * [三：RHEL 7.2 配置KVM主机](https://github.com/huataihuang/cloud-atlas-draft/tree/6f3204fffc11cf006abd394631e2598d98b415c3/virtual/kvm/startup/rhel_7_2_configuring_kvm_hosts/README.md) * [四：使用命令行启动第一个KVM实例](https://github.com/huataihuang/cloud-atlas-draft/tree/6f3204fffc11cf006abd394631e2598d98b415c3/virtual/kvm/startup/launch_the_first_kvm_instance_using_cli/README.md) * [五：使用Virt-Manger(VMM)部署KVM实例](https://github.com/huataihuang/cloud-atlas-draft/tree/6f3204fffc11cf006abd394631e2598d98b415c3/virtual/kvm/startup/deploy_kvm_instance_using_virt_manger_vmm_gui/README.md) * [六：如何克隆一个KVM虚拟机并重置该虚拟机](https://github.com/huataihuang/cloud-atlas-draft/tree/6f3204fffc11cf006abd394631e2598d98b415c3/virtual/kvm/startup/how_to_clone_a_kvm_virtual_machines_and_reset_the_vm/README.md) * [七：如何在线添加/更改虚拟磁盘](https://github.com/huataihuang/cloud-atlas-draft/tree/6f3204fffc11cf006abd394631e2598d98b415c3/virtual/kvm/startup/how_to_add_resize_virtual_disk_on_fly/README.md) * [八：如何在线添加/移除虚拟机的内存](https://github.com/huataihuang/cloud-atlas-draft/tree/6f3204fffc11cf006abd394631e2598d98b415c3/virtual/kvm/startup/how_to_add_remove_memory_to_guest_on_fly/README.md) * [九：如何在线添加/移除虚拟机的vCPU](https://github.com/huataihuang/cloud-atlas-draft/tree/6f3204fffc11cf006abd394631e2598d98b415c3/virtual/kvm/startup/how_to_add_remove_vcpu_to_guest_on_fly/README.md) * [十：更改libvirt虚拟机镜像存储路径](https://github.com/huataihuang/cloud-atlas-draft/tree/6f3204fffc11cf006abd394631e2598d98b415c3/virtual/kvm/startup/change_libvirt_vm_image_store_path/README.md) * [十一：实现Linux KVM在线迁移](https://github.com/huataihuang/cloud-atlas-draft/tree/6f3204fffc11cf006abd394631e2598d98b415c3/virtual/kvm/startup/perform_live_migration_on_linux_kvm/README.md) * [十二：RHEL7 Pacemaker - 配置高可用KVM虚拟机](https://github.com/huataihuang/cloud-atlas-draft/tree/6f3204fffc11cf006abd394631e2598d98b415c3/virtual/kvm/startup/rhel_7_pacemaker_configuring_ha_kvm_guest/README.md)