Over the last few years a great many companies have deployed Networked Storage of one sort or another. Generally, these solutions are sold on the basis of simplifying the management of storage and improving the utilisation of that storage. The two classical solutions for networked storage are of course the SAN - Storage Area Network - and the NAS - Network Attached Storage. In addition, those companies that have installed SAN, NAS, or both, as well as those that have yet to deploy either solution, also have significant amounts of storage captive within existing servers and indeed desktops and notebooks.
At its simplest, Storage Resource Management is about managing the actual storage resources, ensuring that everything is done that needs to be done. In reality technologies like SAN and NAS provide the connectivity and access to the data, just as a server with captive storage does indeed give access to storage capacity.
This is perhaps one of the most significant causes of confusion on what Storage Resource Management is and whether there are tools that deliver valuable benefits to companies. After all, SRM is equally applicable to captive storage in servers, desktops, and notebooks, as it is to NAS-based storage and SAN-based storage solutions.
What is SRM really about?
Even saying that SRM is about managing storage, wherever that may be, does not totally clarify what the tools are actually doing. The SNIA model for storage management makes things a lot clearer, particularly looking at the SMI-S Management Services Diagram. This shows, very clearly, that at the top there are the applications with storage devices at the bottom. In between there may be file systems, databases, storage networks and so on.
The objective of storage resource management must therefore be to provide the right storage resources for the applications. From an application perspective, it needs storage of a given performance, with a certain level of availability at a given cost. Over time, the application may gradually need more space. Indeed, other requirements may change as the use of the application changes within an organisation.
So SRM is about the mixing and matching of applications to storage. By talking about SRM as apposed to SAM (Storage Area Management) it must be about the wider storage that an organisation has, not just one of the sub-pools of storage mentioned earlier. Therefore, a good SRM tool must focus on delivering its management capabilities in the context of the storage administrator's day-to-day tasks:
• Allocate storage to an application - the right storage for the right job
• Ensure the application has the availability it needs through replication, backup, etc
• Ensure that SLAs are met, that applications are not slowed down by poor storage performance, or broken because they run out of storage.
What about virtualisation?
A very confusing side issue is virtualisation. A SAN or NAS in its own right does not do SRM, though clearly these technologies do provide the connectivity and flexibility that make SRM easier to implement. Virtualisation, on the other hand, if fully realised, does far more in terms of taking a pool of storage and seamlessly providing servers and applications with the storage they require.
Is this SRM? Nearly, virtualisation technologies provide a lot of the intelligence necessary to manage storage resources. But in a very real sense you still need, somewhere, some form of management console. This is to define the rules and requirements and to provide visible monitoring that the applications are getting what they need.
Do the tools exist?
Is there an all-singing, all-dancing SRM tool that will meet all the requirements of any given IT department? No. Are their valuable SRM tools in the market? Yes. The first stage is to work out what your exact requirements are. Before looking at SRM tools, the critical step is for a company to look at their storage-related tasks. How often are these tasks carried out? How long do they take? And what tasks are being ignored or missed for some reason? By looking at how the IT staff spend their time in managing the storage, it should be possible to identify what functionality is required in the SRM tools to make the computer room operate more effectively.
Finally, it may well be that you will need more than one tool; possibly one to implement SRM functionality for the SAN and another for the NAS or the captive storage. It may be that you will need one tool, or set of tools, to implement the storage allocation processes - and there are some good tools in this space - as well as a separate set of tools to do capacity planning or performance analysis. At least by analysing how time is spent managing the storage, it is possible to identify where the biggest gains can be achieved. After implementing SRM tools it can also help monitor that the expected benefits are achieved.