In my last post, I talked about 5 building blocks of the cloud, taken from the book “Cloud Storage for Dummies.” As a reminder, these were:
- Elastic, quickly adapting underlying infrastructure to changing subscriber demands
- SLA-driven, automated and integrated to provide swift response times
- Policy-based, with deep levels of automation to move data as required
- Secure and reliable
- Able to control geographically dispersed data
Now let’s take the points above and simplify them a little more to describe cloud-enabled storage:
- Cloud-enabled storage is virtual – data is not bound by physical arrays or geography
- Cloud-enabled storage is elastic – storage resources can be assigned transparently
- Cloud-enabled storage is automated – pre-defined policies dictate the behavior of data
- Cloud-enabled storage is secure – tenants share each other’s resources but not their data
I’ll come back to those 4 points in later blogs, but in this blog I want to discuss a problem that emerges when you have a virtual, elastic, automated, and secure IT infrastructure. That problem: how do you figure out who pays for the storage services you are providing?
In the old days, a project manager would go IT and said “I need a couple servers and 10TBs of storage for my new application.” You’d pull out your vendor pricelists and add up all the costs (including network switches, backup software/hardware and of course your valuable time) and tell this manager, “OK I can have that ready for you in a couple months and I’ll need to charge your department around 100 thousand dollars.”
Once you both agreed to this amount, you’d go off and build out this project and when the vendor bills arrived, you’d charge the costs to the appropriate department.
In the era of cloud computing, however, this model changed. Instead of buying servers, you simply create a couple of Virtual Machines. Instead of buying a storage array, you carve some storage capacity out of your internal cloud and assign a backup policy. Viola! While your friendly project manager is still standing there with his/her mouth agape, you say “OK that should do it, anything else?”
That’s the beauty of cloud computing and cloud-enabled storage – you can quickly and efficiently serve the IT needs of your organization. The problem is; how to you charge for what you just did? That’s where metering and chargeback come into play. Since the cloud is designed as a “pay-per-use” activity, you need a way to figure out what was used and what your Users should pay.
From the storage perspective, this is easy, right? Well yes it could be – you could simply total all your storage costs and divide this by all your storage capacity and charged a fixed cost per TB. Using the example above, if you’ve invested $1,000,000 in a 100TB storage infrastructure, your cost per TB is $10,000 – and you could bill your friend $100,000 for their 10TB of storage.
The problem is that in this model, you are assuming the same requirements for each User, when in reality we all know that there is fast storage, slow storage, big storage, small…well you get the picture. This kind of level-funding model doesn’t really charge Users for what they are getting.
To try and match costs more exactly, what we usually see IT shops do is divide their storage into 3 or 4 tiers based on loosely defined performance levels, price out each tier, and bill Users according. This is a step in the right direction, but still far from perfect. What about automatic storage tiering, for instance. If an application sees high activity for a few weeks and moves to a higher performance tier, how do account for that? What if your cloud provides automatic migration of data to reduce latency, how do you account for that? The answer is automatic metering and a chargeback based on actual usage – something most people haven’t given much thought to, unless of course your business depends on the profits from providing Storage as a Service (STaaS.)
Since the typical IT shop doesn’t need to make a profit, chargeback is used as a means of covering costs, and metering is a way to charging Users fairly . Metering and chargeback utilities are provided by nearly all major storage providers today – and provide a way to charge Users based on actual usage. If you are using a chargeback system today (or would like to) and you are moving to a cloud infrastructure, this would be a good time to analyze your methodology. Here are few questions you should ask:
- Does your chargeback have a sliding scale based on storage tiers?
- How does your chargeback account for automated tiering?
- Is your chargeback pricing based on logical storage capacity or physical capacity?
- Does your chargeback pricing take high performance IOPS into account?
Metering and chargeback is an area that is sure to see more interest as we move more deeply into cloud and cloud-enabled storage.
For more on this topic, here are a few storage-brain recommended resources, including User Guides for a couple of popular chargeback utilites:
http://storage-brain.com/wp-content/uploads/papers/IBM_definingframeworkforcloud.pdf#search=
http://storage-brain.com/wp-content/uploads/papers/Storage%20Chargeback%20User%20Guide.pdf
http://storage-brain.com/wp-content/uploads/papers/vCenterChargeback_v10_Users_Guide.pdf
