While Microsoft's Hyper-V has proved its ability to fulfill enterprise-level needs, Hyper-V version 1.0 featured significant shortcomings, such as its management toolsets and a Hyper-V Manager console that is rough around the edges. Luckily, Microsoft designed System Center Virtual Machine Manager (SCVMM) to overcome these obstacles.
In this continuation of our three-part series on SCVMM R2, we discuss some of the upgrade's features and their improvements to Hyper-V management, including logical unit number (LUN) management and Live Migration support. In part one, we explored the top seven features justifying an upgrade to SCVMM .
Drawbacks of Hyper-V version 1.0
Hyper-V's hypervisor has proven it can keep pace with or even outperform its competitors, including VMware and XenServer. Hyper-V is an easy sell for single-OS environments because it relies on Windows Server 2008 as its platform. So if you understand how to manage Windows Server, the jump to managing virtualized Windows Server environments isn't a big step.
The problem with Hyper-V version 1.0 is the Hyper-V Manager console. Hyper-V Manager focuses on the management of individual virtual machines (VMs) instead of groups of VMs. In addition, working with virtual machines in a high-availability (HA) environment is a chore, with commands spread across multiple consoles. Although it performs basic administrative actions for individual VMs, Hyper-V Manager doesn't offer much else.
features in SCVMM 2008 R2
Enter SCVMM 2008 R2. The console was designed to address the shortcomings of Hyper-V Manager by facilitating several functionalities that admins have clamored for since adopting Hyper-V v1.0. The most important features in SCVMM 2008 R2 include the following:
Live Migration support. Since the initial release of Hyper-V, the most requested improvement is parity with VMware on virtual machine migration. Hyper-V version 2.0 includes the ability to migrate VMs from one host to another with zero downtime. This feature not only offers the ability to relocate VMs for maintenance but also enables VM load balancing on par with ESX and VirtualCenter. For more information, check out this tip on Live Migration in Hyper-V version 2.0.
Hyper-V's reliance on Windows Failover Clustering increases the complexity associated with migrations and failover. SCVMM addresses this problem by removing the reliance on the Failover Cluster Manager for initializing migrations. Both manual and automated migrations are incorporated into the SCVMM console.
Improved LUN management and configuration. The initial release of SCVMM 2008 supports only initiator-based connections to iSCSI targets. Hyper-V version 1.0 environments not only lack a cross-host locking mechanism for shared drives but also are limited to a single VM per LUN. This isn't a major problem in small environments, but it's an operational nightmare for large environments.
With Hyper-V version 2.0 and SCVMM 2008 R2, you can create large LUNs containing more than one VM because of two features: Cluster Shared Volumes and LUN-masking support. Masking enables a LUN to be available to some hosts and unavailable to others, ensuring that the right hosts see the right disk resources.
- Cluster Shared Volumes is a capability in Windows Failover Clustering. It creates shared ownership of specific files on a disk between all hosts in a Windows Cluster, whereas clusters in Hyper-V v1.0 were aware only of resource ownership bound by the disk itself. Cluster Shared Volumes enables hosts to share -- and therefore determine ownership of -- individual files on a disk resource. Cluster Shared Volumes has a certain elegance in that it isn't a file system but instead a protocol layered on top of a standard Technology File System (NTFS) that enables the sharing functionality on cluster disks. For more information check out this tip on Cluster Shared Volumes .
Management enhancements. SCVMM 2008 R2 enables you to migrate VMs from one cluster to another within its interface. In addition, it can migrate VMs from single hosts to clusters for HA purposes. If you manage multiple clusters because of operational requirements or resource limitations, this feature facilitates the process of relocating VMs.
SCVMM 2008 R2 also offers support for domains that have disjoined name spaces. While most environments share the same Domain Name Server name space as their domain name, some organizations don't because of mergers or political reasons. Organizations that don't follow this practice require custom Server Principal Names (SPNs) to be manually created in Active Directory. SCVMM R2 automatically creates custom SPNs when necessary.
- Network optimization. Keeping multiple VMs on a single host increases the amount of network traffic going through that host dramatically. Network optimization tools such as Microsoft's Virtual Machine Queue and TCP Chimney Offload are available in SCVMM 2008 R2 to assist environments with the hardware to support these protocols. In high-traffic situations, enabling either of these tools improves overall network performance. Another SCVMM also features the networking improvement for load balancing Media Access Control (MAC) address spoofing, which is a setting exposed in the console.
- Disk improvements. An improvement to disk resources in SCVMM 2008 R2 is the ability to add and remove disks from running virtual machines. This feature allows you to add additional disks to your production servers before you run out of space without incurring downtime.
- Maintenance mode. Another management improvement is the ability to move a host into maintenance mode. When maintenance mode is activated on a host, all running VMs on that host are automatically migrated to other hosts in the cluster. Also any VMs in the cluster will not be positioned on that host while it's in maintenance mode.
So while the interface appears the same in SCVMM 2008 and SCVMM 2008 R2, the underlying capabilities have matured. SCVMM 2008 R2 is currently a release candidate, with a release date coming later in 2009. In the final article in this series, we cover some of the prerequisites and gotchas involved in installing SCVMM 2008 R2 and run through the installation process.
|Greg Shields, MCSE, is an independent author and consultant based in Denver with many years of IT architecture and enterprise administration experience. He is an IT trainer and speaker on such IT topics as Microsoft administration, systems management and monitoring, and virtualization. His recent book Windows Server 2008: What's /What's Changed is available from Sapien Press.|