GreenBytes: GreenPower Blog

The Capacity Creep Dilemma

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Apparently, judging by the response to my previous post, everyone is struggling to find ways to reduce the storage explosion in their data centers.  So, let's discuss one of the major problems in data storage that has a fairly simple solution.  A problem I call the "Capacity Creep Dilemma."

The Capacity Creep Dilemma occurs when the following scenario plays out in an IT organization:

1.     A developer, tasked with creating a new application, requests storage for his/her new project.  In this example, will use a 100GB storage requirement.

2.     The storage administrator, receiving this request, thinks to himself, "I know this person is always wrong so I'll setup 200GB." And, having no available capacity on the SAN, submits an expansion request to purchase a new tray of disks.  After running his RAID calculator for RAID5 with 146GB drives and a hot spare, he nets out a request for 4 drives or 600GB.

3.     The storage manager, having dealt with the storage administrator before, knows that there are probably other requests that haven't been fulfilled and it's cheaper to buy a full shelf of 15 drives than a partially populated one.  Therefore, requests from purchasing the acquisition of 15x146GB drives or 2190GB of storage.

4.     The purchasing, privy to the year-end "deal" gets a buy-one-get-one offer and submits an order for two shelves, which yields nearly 4.5TB of storage. 

This case may seem extreme, but these scenarios play out every day.  Take a serious look at you current SAN and calculate the amount of data stored for the primary copy versus the physical disk it resides on.  Odds are your real utilization rate is around 25-30%.  And that would be the best-case scenario.

So, how do you solve this problem?  The reality is, unless you are willing to make fundamental changes in architecture and habit; you may not.  But the good news is technology has changed.  Most of these rituals are predicated on 10-12 years of SAN purchasing habits.  But, the technology that we have today is not the same Fibre Channel based architectures of yesteryear.

It is time to move from physically tying the data to the drive.  By creating an abstraction layer between the physical device and data set, customers can provision volumes more quickly and increase utilizations.  One of the big problems in the past was getting the spindle count high enough to hit performance needs, but not have too much excess capacity lying around.  By utilizing a high-speed file system such as GBFS you can have the best of both worlds.  GreenBytes allows you to have both NAS and block-level storage presented without physically tying you down to an individual spindle or spindle set.  Everyone knows the actuator is the slowest moving part - why strap your performance to it?

And to think, we haven't even touched on improving efficiency with Thin Provisioning or Deduplication.  Take all the functionality that virtual servers have brought to the server team and apply it to storage.  With GreenBytes, you can.