By Noemi Greyzdorf
Thin provisioning has become one of the hottest storage technologies. There is some consensus among vendors and end users regarding what thin provisioning means—fundamentally or theoretically—but to level the field, let’s define the concept for the purpose of this article.
- Thin provisioning is a process by which additional capacity is dynamically added to an application as the need arises. In other words, administrators don’t have to allocate capacity based on the total capacity to be consumed over the life of the storage system, but only the amount the application currently needs. Thin provisioning provides additional capacity on-the-fly. With thin provisioning, once data is deleted, the excess capacity is returned to the general pool to be used by other applications if necessary.
- Thin provisioning automates the process of adding or taking away capacity without intervention from the storage administrator.
- There is a clear path to expanding available capacity if total system usage reaches pre-defined thresholds. Capacity is added as-needed.
The rest of this article addresses three issues around thin provisioning: what to look (out) for, the business value, and when not to use thin provisioning. Let’s start with what thin provisioning isn’t:
- If you can’t add capacity on-the-fly without administrative intervention, it’s not really thin provisioning;
- If you have to migrate data to add or reduce capacity, it is not thin provisioning;
- If you have to set storage pools aside for specific applications from which capacity can be provisioned, it is not thin provisioning;
- If it doesn’t tell you when you have reached the threshold of total system capacity, thus causing you downtime, it is not thin provisioning; and
- If you have to buy all capacity up-front, it is not thin provisioning.
If you deploy thin provisioning that doesn’t align with the above criteria, you might not see the business benefits that the technology promises. However, if thin provisioning is deployed properly, IT organizations can realize significant financial and operational benefits.
In today’s energy-conscious world, everyone is looking for ways to reduce their carbon footprint, and technologies that help IT accomplish these objectives are receiving more attention. Thin provisioning can reduce your carbon footprint.
Here is an example of how it accomplishes that goal: Company A has an application that today consumes 200GB. Over the next three years, application owners expect it to grow to 2TB. Traditionally, the full 2TB would be provisioned on day one, with the spinning drives consuming space and power.
By using thin provisioning and adding capacity as needed, the organization can reduce its power, cooling, and space requirements. If the amount of savings realized is multiplied throughout the organization, it could be significant.
The same example can be used to demonstrate the financial implications. Assuming Moore’s law still stands and capacities double while prices fall, a drive purchased today will either be twice as dense at the same price or cost half as much for the same capacity 18 to 24 months from now. If you can delay purchase of 10 drives you could save on a per-gigabyte basis plus any opportunity costs. (Opportunity costs are what you could have done with this money if you were not buying drives, and factors in the return on investment.)
Another cost that can be reduced is associated with licensing. Many storage vendors license replication and snapshot software, as well as other types of software on the array, based on the total capacity of the system. By reducing the capacity, or delaying it, an organization saves on software licensing costs.
Of course, these calculations are generalized and theoretical, and results will vary from company to company.
There are some circumstances where thin provisioning might not be appropriate:
- If you have to sacrifice capacity efficiency to achieve desired I/O performance;
- If you only get a budget for capital expenditures every three years and you can’t afford the risk of running out of capacity; and
- If your application consumes capacity in spurts, unexpectedly making planning and forecasting complicated, difficult, or impossible.
Don’t jump on the thin-provisioning bandwagon without taking the time to understand the implications of deploying it in your environment. Consider all variables in your assessment related to organization, infrastructure, and application requirements. But don’t dismiss thin provisioning either. Many solutions are available. Decide how important thin provisioning is to your organization, and then evaluate offerings that best meet your requirements.
Noemi Greyzdorf is a research manager at IDC (www.idc.com).