Dynamic Infrastructure: VMM PRO vs. Distributed Resource Scheduler
Dynamically changing your system configurations to meet changing workload requirements is another feature that IT administrators are concerned about.
Microsoft’s virtualization management platform addresses dynamic IT management via the VMMs Performance Resource Optimization (PRO) feature. VMMS PRO works in combination with Ops Mgr and can automatically initiate Live Migration in response to host or VM CPU or memory utilization levels.
VMware addresses the issue of dynamic management with its Distributed Resource Scheduler (DRS) feature. Similar to VMM PRO, DRS can automatically invoke VMotion to move VMs between ESX Server hosts based on resource utilization. However, DRS uses more advanced features such as a global scheduler and Resource Pools to provide a finer level of control over how and when VMs are moved. DRS can be coupled with Distributed Power Management (DPM) to automatically shut down servers when the workload decreases, then later dynamically power up again to meet increased user demand.
Storage: Quick Storage Migration vs. Storage VMotion
Storage management is another important concern of IT administrators.
Server 2008 R2 includes a new Quick Storage Migration feature. As was the case with Quick Migration, Quick Storage Migration is a feature that’s not quite up to the standards set by the competition.
Quick Storage Migration enables you to rapidly move VMs to different storage locations. With Quick Migration, there's some downtime as the VM’s state is saved, then restored when it's in the new location. It's primarily designed to enable you to take advantage of Server 2008’s ability to run multiple VMs per LUN. (Previous versions of Hyper-V required one VM per LUN, which was difficult to manage.)
Quick Storage Migration lets you quickly consolidate your VMs together on a larger shared LUN.
VMware’s Storage VMotion provides the same type of ability to move VMs to different storage locations. However, Storage VMotion is a generation ahead of Quick Storage Migration. Like its namesake VMotion, Storage VMotion enables you to move VMs between different storage locations with no downtime.
Performing a storage VMotion takes roughly the same amount of time as performing a cold migration of a VM’s files to a new LUN.
Backup: DPM vs. VMware Consolidated Backup
Backup is another important consideration in the management of your virtual infrastructure. You can achieve a very basic level of backup for your VMs by using Windows Server Backup on the Hyper-V host. However, Windows Server Backup is extremely limited as it's a volume-oriented backup.
System Center Data Protection Manager (DPM) 2007 provides a much more capable backup platform. DPM can provide host-based backup for Hyper-V VMs as well as other Microsoft server platforms such as SQL Server, SharePoint, and Exchange. DPM is also able to perform DPM to DPM replication for offsite protection.
For backup tasks, VMware’s vSphere provides VMware Consolidated Backup. VCB provides both full and incremental backup of VM files. It can also run on another server by proxy, which allows it to reduce the load required on the host while the backup operation is performed. VCB enables you to recover whole VMs as well as individual folders and files from inside a Windows VM. VCB isn't integrated with any Windows Server applications.
System Center Features Not Found in vSphere
Because of its holistic view of the different IT resources in the enterprise, System Center Enterprise Management Suite has many features that vSphere doesn't have. Some of them include the following:
• Management of all physical systems—Ops Mgr is able to monitor the health of both physical and virtual servers. vSphere manages only the components of a virtual infrastructure. vSphere can monitor the performance of ESX Server hosts.
• Heterogeneous VM Management—VMM supports management of both Microsoft’s Hyper-V hosts and VMware ESX Server's hosts, if VMware’s vCenter Server is present.
• Deep management of applications including SQL Server, Exchange, and SharePoint—In addition to hardware and OS monitoring, Ops Mgr is also able to manage Microsoft server applications including SQL Server, Exchange and SharePoint. vSphere doesn’t provide application management.
• Application level backup and restore—DPM can back up and restore Microsoft servers such as SQL Server and Exchange. VCB backs up at the VM level and can restore individual files, but it's not application aware.
• Software inventory, deployment, and management—Configuration Manager’s ability to inventory hardware and software and to deploy OSs, applications, and updates has no equivalent in vSphere.
vSphere Features Not Found in System Center
vSphere maturity shows in the types of virtualization management features that aren’t found in Microsoft’s System Center suite. Some of the main features that have no counterpart in System Center include these:
• Broad support for popular Linux distributions—vSphere’s ESX Server fully supports all of the popular Linux distributions. While other distributions can run on Hyper-V in legacy mode, Microsoft supports only SUSE on Hyper-V using the higher performance VMBus architecture.
• Multiple VMotions—vSphere can per¬form multiple concurrent VMotions. Hyper-V is limited to one Live Migration at a time.
• Support for multiple virtual CPUs on Linux—ESX Server supports up to four-way virtual CPUs for Linux. Hyper-V supports only a single virtual processor for Linux VMs.
• NIC teaming—Thanks to its direct control over the drivers, ESX Server supports NIC teaming on all types of NICs. Hyper-V doesn’t directly support NIC teaming but can take advantage of it if it's provided by specific network adapter drivers.
• Memory Over-Commitment—ESX Server also support the ability to make the memory requirements of the running VMs exceed the physical memory in the host. This lets you potentially run more VMs per host, but there's a performance hit for using this feature.
• Distributed Network Switch—Enables you to create and share network configuration between multiple servers.
• Distributed Power Management—Another advanced virtualization feature, Distributed Power Management (DPM), enables vSphere to optimize power consumption by using VMotion to move VMs off lightly loaded hosts, then power those hosts off.
Licensing
No comparison of platforms is complete without looking at how much it costs to deploy each platform. Table 1 compares the basic licensing costs to deploy 10 physical servers with each server running 10 VMs apiece. This comparison is created with the assumption that you're deploying 10 dual-core servers. I didn’t include server costs, as the hardware required for each platform is essentially the same.
In Table 1, you can see that the costs for Server 2008 Datacenter edition are the same for both platforms. The Datacenter edition is the best Server 2008 choice because it permits an unlimited number of virtual Windows instances with no additional licensing costs. Likewise, the virtualization software itself is included with each platform.
The biggest difference is in the management suite. vSphere is licensed by CPU socket and is a bit more expensive. Plus, the required vCenter Server must be purchased separately. VMware vSphere is the more expensive virtualization management platform.
However, it also offers many virtualization features that aren’t in the Microsoft platform. I have seen alternative licensing comparisons that show better advantages for the VMware platform. But most of these are based on running more VMs per server. That isn’t necessarily a given.
Hyper-V supports workloads comparable to those ESX Server supports, certainly up to the 10 active VMs per host server on which this comparison is based. That said, the new 64-bit version of ESX Server 4.0 clearly provides better performance than previous version. In a coming issue of Windows IT Pro magazine we’ll revisit the performance comparison of the new ESX Server 4.0 and Hyper-V R2.
A Generation Ahead vs. A Cheaper, Broader Reach
VMware’s vSphere is a generation ahead of Microsoft’s System Center as far as virtualization management is concerned, but the Microsoft platform is less expensive and has a broader reach over what it's designed to manage. Although each virtualization management platform has certain advantages, there's also a different guiding philosophy behind each platform.
Microsoft’s System Center Enterprise Management Suite is designed to provide seamless management for both physical and virtual servers.
In contrast, VMware’s vSphere is designed to enable IT to build an internal cloud where all resources are virtualized, and it provides dynamic management of the virtual infrastructure.
Although I looked at the different platforms as alternatives, you can certainly combine these platforms, and many companies do.