vsphere thin provisioning' pros and cons


Can someone point out to me what the pros and cons of vsphere thin provisionings are?

we are debating whether we should thin provisioning some of our VMs.

Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Thin provisioning allows you to create a VM that thinks it has say 100GB of drive space (or whatever limit you set), but on the SAN storage it might only be using 20GB.  As the VM adds more files to the virtual drive (vmdk file) that drive will consume more on the SAN, until it reaches the 100GB limit that you set initially.

The benefit is that you don't use up all your SAN space as quickly.  Many times you might build a Windows server and give it a 40GB C: drive, but in reality it is only using 12GB or 15GB of that space.  So why should you have 25GB of empty space that you can no longer use on your SAN?  Who knows when that Windows VM will ever get to the full 40GB that you allowed?  You might be able to fit as many as 3 times as many VM's on your SAN using thin provisioning.

The drawback is that you can very easily over-provision your SAN.  If you have a 100GB SAN, and you build 5 VM's, each with a 40GB drive, thin provisioned, they will fit on your SAN easily, and you might even have space left over.  However, as those VM's add files, their vmdk file can grow to the 40GB that you originally allocated.  If all 5 VM's grow to their 40GB limit then whoops!  You're trying to use 200GB of space on your 100GB SAN, which just doesn't work.

It can be a good tool, but you need to be aware and be careful not to over-provision your SAN by too much.

fireburn11Author Commented:
Hi Thomasdietrich:

Thanks for your input.

Will there be any performance issue that may occur if we go thin provisioning?

Here's a study on the topic.


Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today

From novice to tech pro — start learning today.