It’s easier to manage a group of things than individual objects.  Consider filesystem directories as a way to organize and secure files, or Active Directory groups as an efficient means of assigning rights to users.

VMware vSphere Resource Pools — introduced in VI3, circa 2006 — give administrators a way to aggregate resources from multiple hosts in a cluster and then subdivide them to meet a range of business needs.  After creating pools of CPU and memory with reserves and limits, virtual machines are simply dragged as necessary to guarantee performance or prevent less-critical workloads from causing interference.

Resource Pools are a proven means to reliably share infrastructure.  So much so that vCloud Director uses them as the foundation for virtual datacenters, separating multiple tenants in a cloud environment.

Hyper-V Hardware Silos

One can learn a lot about Hyper-V by reading Virtual PC Guy’s Blog — Ben Armstrong cuts through the marketing fog and provides clear technical information on a range of Microsoft virtualization topics.  Thanks to his recent recent series on CPU resource management, it’s quite clear that Hyper-V has a long way to go before it can match the flexibility and ease of VMware vSphere.

For now, Hyper-V administrators that need to manage resources in a shared environment have few options.  Without any means of grouping CPU and memory resources, the only alternative is to manage individual virtual machines — one by one!  That could mean a significant manual effort any time a VM is added or removed.  Such a process contradicts the desired efficiencies of cloud computing and is infeasible.  To achieve guaranteed resources in a multi-tenant cloud would therefore imply silos of physical Hyper-V clusters.

Top Hyper-V Resource Management Weaknesses

After looking at the differences between resource management in VMware vSphere and Hyper-V, it is clear that the Microsoft offering has a number of disadvantages:

• CPU reserves, limits, and shares are specified on a VM-by-VM basis — no grouping or pooling
• System Center Virtual Machine Manager 2008 cannot even configure reserves and limits, forcing administrator to turn to an alternate management interface (so long, single pane of glass!)
• When resource reservations are calculated, it appears that:
  • Host (parent partition) CPU resource requirements are either not considered or hidden from view — administrators can reserve 100% of host resources for virtual machines
  • Logical, hyperthreaded CPUs are treated as  full physical cores — on a host with 8 cores and hyperthreading enabled, a VM with 4 virtual CPUs will only reserve 25% (not 50%) of the total system resources:

Concluding

VMware vSphere provides Resource Pools to group and control virtual machines according to resource requirements and are configured through the same user interface used for all vSphere management tasks.  The hypervisor host is given an explicit reservation to ensure reliable scheduling and I/O operations, and hyperthreaded cores are not double-counted by treating them as full physical cores.

VMware offers the only platform that enables reliable shared infrastructure through resource pooling and is the best foundation for your private cloud infrastructure.

Related posts:

1. VM Resource Management: Hyper-V versus SCVMM
2. Don’t know much about resource pools
3. SCVMM Damage Control
4. New: vSphere Resource Distribution Chart

The Processor option is used to set the number of virtual CPUs and the CPU type.   The latter sure is confusing, and according to the online help:

These settings do not specify actual hardware, however, VMM uses these settings to calculate host ratings and to set CPU resource allocation.

VMM, not Hyper-V, uses that CPU type for something, but it does not sound like resource management of running VMs.  I suspect this is limited to the intelligent placement feature, the one-time recommendation of a host when provisioning or migrating a VM.

The Priority option looks like CPU shares on VMware ESX –  a means of specifying which VMs will receive priority when there is contention for resources.

As far as I can tell, there are no more CPU resource settings available in SCVMM.

It turns out that with Hyper-V Manager, the other single pane of glass, it is possible to set CPU reservations and limits for individual VMs:

It’s hard to understand why this configuration option did not make it into the SCVMM administrator console, which is supposed to be a panacea for “physical and virtual management.”  Virtualization administrators that need to control VM CPU resources are forced to open another management tool in order to do so.  (And that other utility does not run on Windows XP, by the way.)

Not only do VMware VI3 administrators have a single client for managing all aspects of their hosts and virtual machines, they have something else: resource pools.  Why manage resources for individual machines when you can place them in containers that partition CPU and memory from an entire hypervisor farm?

No experienced administrator would make a practice of applying permissions to individual user accounts instead of a group.  That doesn’t scale and just increases your OpEx.  Why not expect the same maturity in your VM resource management?

Related posts:

1. Resource Pools to the Rescue
2. Don’t know much about resource pools
3. Network World weighs in on SCVMM-VI3 Management
4. Single Pane of Glass — Hyper-V Edition

The resource pool is a means of partitioning CPU and memory, and it is also convenient for configuring access control.  Let’s say you have a DRS cluster with a resource pool for your web QA team.  When a QA engineer logs in with VI Client, he sees only the virtual machines that he has permission to access.

Now, let’s say that one of your fellow administrators wants to use SCVMM to manage this VMware environment.  He uses the SCVMM console to migrate a QA virtual machine from one ESX host to another in order to perform maintenance.

The VMotion completes without incident and everything seems OK…

Before too long, a QA engineer is on the phone asking what happened to his VM.  From his perspective, the VM has disappeared.

It’s not really gone, it has just been moved out of the resource pool.  Fortunately, you can log in with the VI Client and fix this problem by moving the VM back to the resource pool.

Do you really think that SCVMM is going to be your single pane of glass for virtualization management?

Related posts:

1. Resource Pools to the Rescue
2. Managing VI3 with SCVMM considered harmful
3. VM Resource Management: Hyper-V versus SCVMM
4. Using SCVMM to attach ISO images to VMware ESX VMs