In the last couple of newsletters we discussed some of the long-standing concepts that underlie cloud computing. We also discussed a few somewhat newer concepts, such as the dynamic movement of virtual machines (VM). In this newsletter we will discuss how the concept of dynamically moving VMs is causing us to lose sleep.
There is no doubt that the ability to dynamically move VMs between physical servers either over a LAN or a WAN is exceptionally powerful as it allows the IT organization to:
- Optimize IT resources for maximum utilization, flexibility and availability.
- Allow IT organizations to perform hardware maintenance without scheduled downtime.
- Improve performance by moving virtual machines away from failing or under-performing servers.
There is also no doubt that it is extremely difficult to dynamically move servers between physical servers in part because it is not just the VM that has to be moved. As part of migrating a VM from one server to another, the IT organizations has to ensure that the migrated VM retains the same security, storage access and QoS configurations and policies as it had previously. If some form of server load balancing is being performed, another challenge is to ensure that the server load balancer can account for the fact that one or more VMs have been moved. If an application firewall was protecting the VM prior to its being moved, an equivalent application firewall must be in place to protect the VM after it has been migrated. If an IT organization is performing specific logging and/or auditing as a way of ensuring PCI compliance, then that functionality would have to migrate along with the VM that hosts the application.
As noted, ensuring that as a VM migrates from one physical server to another, that all of the requisite functionality follows it is extremely difficult. The only way that this will happen, if indeed it does, over the next few years is if IT organizations keep the environment as simple as possible. This means that IT organizations must choose one primary vendor for their virtualized data center. That is setting up to be a choice between HP, IBM and friends such as Juniper, and Cisco and friends such as VMware and EMC.
We do think the benefits of a virtualized data center are compelling. However, we also think that having to choose between Cisco, HP and IBM will be a wrenching decision for many IT organizations.