Virtualization: Thin on Thin Provisioning – Good Idea or Recipe for Disaster?

Virtualization: Thin on Thin Provisioning – Good Idea or Recipe for Disaster?

I was part of a panel at a recent GreenPages event and a question was asked by the audience regarding best practices for thin provisioning in a virtual environment.  More specifically, the question was, what is the best practice regarding thin on thin storage provisioning?

First, let me provide a bit of background on the question.  Thin Provisioning is essentially a process for “faking out” an operating system or other platform in such a way that you make it believe it has more storage available than what truly physically exists.  Why would I want to do this, you may ask?  There are several reasons why this could make sense, such as that pesky application vendor who demands that you provision 200GB of disk space for a database that you know will only truly use maybe 5-10GB.  It also allows for dynamic growth as one can add the true physical capacity to meet the ‘advertised’ capacity if/when necessary without any alterations needed within the OS or application.

So, “how” do I use this technology?  Herein lies the challenge as there are really multiple ways to accomplish this.  One method is within the virtual infrastructure itself, as I can create a virtual disk with a size of 100GB and choose to “thin provision” it.  This means that the virtual disk actually starts out with a much smaller size than 100GB, and will dynamically grow as new data is created within the vdisk.  The full 100GB is advertised to the OS, so it believes there is 100GB of capacity available even though in reality there is probably less than that.  Hopefully you can see the challenge here from a management aspect.  Take a single VMFS volume with a physical size of 500GB and, let’s say, I create 10 VMs on that VMFS volume, each with a single 100GB thin provisioned vdisk.  I’m advertising 1TB of capacity collectively to the VMs, but I really only have 500GB there.  What happens when the total used capacity of the 10 VMs reaches 500.0001 GB??  Let’s just say that wouldn’t be a good day for the VMware administrator.  So I need a way to monitor the actual used capacity and be alerted far enough in advance of the 500.0001 problem so that I can add additional physical capacity or move VMDKs around to avoid running out of space.

Another method of thin provisioning involves the shared storage array itself.  In this situation, we are provisioning a LUN or Datastore and advertising that it has a size of 1TB when in reality there is only 500GB of actual capacity on the array.  Same situation as above, but in this case I will typically use true ‘thick’ provisioning on the actual virtual disks themselves, meaning that I could only create 5 VMs with each having a 100GB vdisk on this thin provisioned datastore.  I can run into a similar issue with the monitoring here as I need to be notified in advance so I can move things around or add physical capacity prior to attempting to add that 6th VM to the datastore.

This brings us to the “thin on thin” question posed to the panel.  This concept basically means that I’m using both of the above mentioned methods simultaneously.  The good news is I can advertise a ton of capacity although I may be truly using only a small fraction of that space.  The bad side of this is I REALLY have to continuously monitor and manage this environment because the edge of that storage capacity cliff gets pretty blurry when both methods are used.  It has always been the recommendation of GreenPages that our customers choose to use one method or the other, but not both, as to minimize the risk of driving the car off the cliff while thinking you have a nice straight paved road in front of you.  As for which method is the best to use, well the consultant in me always says “it depends” because everyone’s business and technical requirements and skill-sets are different so I can’t really say there is a single correct answer in this regard.

By Chris Ward

About CloudTweaks

Established in 2009, CloudTweaks is recognized as one of the leading authorities in connected technology information and services.

We embrace and instill thought leadership insights, relevant and timely news related stories, unbiased benchmark reporting as well as offer green/cleantech learning and consultive services around the world.

Our vision is to create awareness and to help find innovative ways to connect our planet in a positive eco-friendly manner.

In the meantime, you may connect with CloudTweaks by following and sharing our resources.

View All Articles

Sorry, comments are closed for this post.

Cloud-Based Services vs. On-Premises: It’s About More Than Just Dollars

Cloud-Based Services vs. On-Premises: It’s About More Than Just Dollars

Cloud-Based Services vs. On-Premises The surface costs might give you pause, but the cost of diminishing your differentiators is far greater. Will a shift to the cloud save you money? Potential savings are historically the main business driver cited when companies move to the cloud, but it shouldn’t be viewed as a cost-saving exercise. There…

Despite Record Breaches, Secure Third Party Access Still Not An IT Priority

Despite Record Breaches, Secure Third Party Access Still Not An IT Priority

Secure Third Party Access Still Not An IT Priority Research has revealed that third parties cause 63 percent of all data breaches. From HVAC contractors, to IT consultants, to supply chain analysts and beyond, the threats posed by third parties are real and growing. Deloitte, in its Global Survey 2016 of third party risk, reported…

Digital Twin And The End Of The Dreaded Product Recall

Digital Twin And The End Of The Dreaded Product Recall

The Digital Twin  How smart factories and connected assets in the emerging Industrial IoT era along with the automation of machine learning and advancement of artificial intelligence can dramatically change the manufacturing process and put an end to the dreaded product recalls in the future. In recent news, Samsung Electronics Co. has initiated a global…

5% Of Companies Have Embraced The Digital Innovation Fostered By Cloud Computing

5% Of Companies Have Embraced The Digital Innovation Fostered By Cloud Computing

Embracing The Cloud We love the stories of big complacent industry leaders having their positions sledge hammered by nimble cloud-based competitors. Saleforce.com chews up Oracle’s CRM business. Airbnb has a bigger market cap than Marriott. Amazon crushes Walmart (and pretty much every other retailer). We say: “How could they have not seen this coming?” But, more…

Connecting With Customers In The Cloud

Connecting With Customers In The Cloud

Customers in the Cloud Global enterprises in every industry are increasingly turning to cloud-based innovators like Salesforce, ServiceNow, WorkDay and Aria, to handle critical systems like billing, IT services, HCM and CRM. One need look no further than Salesforce’s and Amazon’s most recent earnings report, to see this indeed is not a passing fad, but…

Do Not Rely On Passwords To Protect Your Online Information

Do Not Rely On Passwords To Protect Your Online Information

Password Challenges  Simple passwords are no longer safe to use online. John Barco, vice president of Global Product Marketing at ForgeRock, explains why it’s time the industry embraced more advanced identity-centric solutions that improve the customer experience while also providing stronger security. Since the beginning of logins, consumers have used a simple username and password to…

Your Biggest Data Security Threat Could Be….

Your Biggest Data Security Threat Could Be….

Paying Attention To Data Security Your biggest data security threat could be sitting next to you… Data security is a big concern for businesses. The repercussions of a data security breach ranges from embarrassment, to costly lawsuits and clean-up jobs – particularly when confidential client information is involved. But although more and more businesses are…

Why Security Practitioners Need To Apply The 80-20 Rules To Data Security

Why Security Practitioners Need To Apply The 80-20 Rules To Data Security

The 80-20 Rule For Security Practitioners  Everyday we learn about yet another egregious data security breach, exposure of customer data or misuse of data. It begs the question why in this 21st century, as a security industry we cannot seem to secure our most valuable data assets when technology has surpassed our expectations in other regards.…

How Formal Verification Can Thwart Change-Induced Network Outages and Breaches

How Formal Verification Can Thwart Change-Induced Network Outages and Breaches

How Formal Verification Can Thwart  Breaches Formal verification is not a new concept. In a nutshell, the process uses sophisticated math to prove or disprove whether a system achieves its desired functional specifications. It is employed by organizations that build products that absolutely cannot fail. One of the reasons NASA rovers are still roaming Mars…