RHEL 6.5 中的KVM虚拟化新特性

昨天看到redhat官网的资料，RHEL 6.5 中会增加许多KVM虚拟化新特性，有些特性在实际工作中可能非常有前景，比如windows虚拟机的agent，原生的支持glusetFS。

抑制不了自己的兴奋，我花了半天时间翻译了这一部分，和大家共享。

以下部分引用自如下连接：

https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6-Beta/html-single/6.5_Release_Notes/index.html

5.1. KVM

Improved Support For the VMDK Image File Format 改进对VMDK文件镜像的支持

Red Hat Enterprise Linux 6.5 includes a number of improvements to read-only support for Virtual Machine Disk, or VMDK, image file formats, including its subformats, as created by many VMware products.

RHEL 6.5 增加了多种只读方式的虚拟机磁盘镜像格式的支持，VMDK等，包括VMWare产品的子格式。

Windows Guest Agent Fully Supported Windows客户端Agent的全面支持

The Windows guest agent is now fully supported and delivered with its own installer in the Supplementary channel together with virtio-win drivers.

现在全面支持Windows客户端Agent，并且和virtio-win的驱动一起在支持渠道发布和交付。

Support for the VHDX Image File Format 支持VHDX文件镜像格式

Red Hat Enterprise Linux 6.5 includes read-only support for Hyper-V virtual hard disk, or VHDX, image formats, as created by Microsoft Hyper-V.

RHEL 6.5 以只读的方式支持Hyper-V的虚拟化硬盘，VHDX镜像格式，为微软的虚拟化引擎Hyper-V创建。

Native Support for GlusterFS in QEMU QEMU 原生的支持GlusterFS

Native Support for GlusterFS in QEMU allows native access to GlusterFS volumes using the libgfapi library instead of through a locally mounted FUSE file system. This native approach offers considerable performance improvements.

QEMU 使用libgdapi原生的支持GlusterFS，取代通过linux FUSE方式挂载，原生方式的支持大大提高了性能。

Support for External Backup of Live Virtual Machines 支持外部的备份工具在线备份虚拟机

Third-party applications running on the host are now able to access the guest image contents in read-only form, thus being able to copy files and perform backups.

第三方应用现在可以通过只读方式读取虚拟机的镜像目录，这样就可以拷贝文件和执行备份。

CPU Hot Plugging for Linux Guests Linux虚拟机CPU热添加

CPU hot plugging and hot unplugging are supported with the help of the QEMU guest agent on Linux guests; CPUs can be enabled or disabled while the guest is running, thus mimicking the hot plug or hot unplug feature.

QEMU支持Linux 虚拟机的CPU热添加，虚拟机运行的时候可以禁止或者启用CPU，这样可以模拟CPU的热添加。

Application-Aware `freeze` and `thaw` on Microsoft Windows with VSS Support on qemu-ga-win Windows 系统上通过qemu-ga实现应用的冻结和唤醒

VSS (Volume Shadow Copy Service) is a Microsoft Windows API that allows, among other things, the notification of applications for proper, consistent freeze and thaw operations. With this feature, snapshots taken while the virtual machine is running are consistent through the whole stack (from the block layer to the guest applications) and can be used for backup purposes. For more information, see theVirtualization Administration Guide

微软的卷影复制服务支持 Windows API，另外一面，可以确切通知应用，保持应用冻结和唤醒时候的一致性，有了这个特性，在虚拟机运行的时候可以通过整个栈（从块设备层到虚拟机应用层）创建一致性的快照以达到备份的目的，了解更多的信息，请参阅文档《Virtualization Administration Guide》

Application-Aware `freeze` and `thaw` on Linux Using qemu-ga Hooks Linux系统上通过qemu-ga钩子实现应用的冻结和唤醒

Similar to the Windows VSS version, application-consistent snapshots can be created with the use of scripts that attach to the QEMU guest agent running on the guest. These scripts can notify applications which would flush their data to the disk during a freeze or thaw operation, thus allowing consistent snapshots to be taken.

同Windows VSS的版本相似，在虚拟机上使用QEMU agent 脚本可以创建应用一致的快照。这些脚本可以通知应用在应用被冻结或者唤醒操作的时候它应该刷数据到硬盘上，这样就可产生应用一致的快照。

Conversion of VMware OVF and Citrix Xen Guests to KVM Guests 支持VMWare OVF和xen的虚拟机转化成KVM的虚拟机

The virt-v2v conversion tool has been upgraded to an upstream version to support conversion of VMware Open Virtualization Format (OVF) and Citrix Xen guest conversion to KVM.

新升级的virt-v2v的工具支持将VMware的开放虚拟化格式(OVF)和思杰的虚拟机转换成KVM虚拟机。

Increased KVM Memory Scalability 虚拟机更多的内存支持

KVM virtual memory scalability in a single guest has been increased to 4TB.

KVM虚拟机内存扩展支持到4TB。

Support of Volume Control from within Microsoft Windows Guests 支持windows虚拟机内部的音量控制

Users can now fully control the volume level on Microsoft Windows XP guests using the AC'97 codec.

使用windows xp 虚拟机的用户现在可以完全控制AC`97的音量。