One of the first advantages of these tools is they allow the storage administrator to manage storage instead of the server virtualization administrator. Often in virtualization, the storage is assigned to the virtualization project and then it is managed outside of the normal storage best practices. Even in cases where the storage and servers are managed by the same person, the presentation of a unified view that these tools provide allows for predictive analysis and quicker problem resolution.
These tools then can provide capabilities like monitoring how specific virtual machines are using storage resources. In the shared file system world of server virtualization, often it is hard to know what virtual machines are using which LUNs or volumes. This makes it challenging to identify storage performance issues and often the storage manager is forced to upgrade performance across the board, even though there is just one virtual machine potentially causing the problem.
With these tools you can identify a storage I/O heavy virtual machine that is causing the other virtual machines to be starved out of storage I/O resources. Instead of applying an upgrade that applies to all the virtual machines, possibly that one virtual machine can be set on its own, potentially on higher performing storage or dedicated I/O bandwidth.
As we discuss in our article "Maximizing Your Server Virtualization Requires Understanding Its Storage", another key capability of these tools is to identify wasted space in virtual machine image files. The files created by virtualization templates often lead to massive storage waste. The template creates an image file at a default size, in most cases the default size is set at a "safe" capacity setting. The problem is that most of the virtual machines in the environment never come close to consuming that capacity. As a result, as the virtual environment grows, tens of TBs of storage capacity are wasted. These tools can help identify and correct those weaknesses.
Simplifying storage management in the server virtualization world requires connecting the abstract to the physical. While tools provided by both the storage and virtualization manufacturers have improved, the need for an external tool often provides better identification of potential problems as well as ongoing predictive analysis. They should be something that most IT organizations consider having on their utility belt.
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George Crump is lead analyst of Storage Switzerland, an IT analyst firm focused on the storage and virtualization segments. Find Storage Switzerland's disclosure statement here.