Another Secret reason why you should purchase VMware Storage VMotion

As most of you already know VMware Storage VMotion is the ability to live migrate a virtual machine from one storage to another without any downtime. The usage most IT Professional relate to VMware Storage VMotion is the following:

The ability to move your virtual machines from a storage or datastore to another for maintenance reason or storage replacement without downtime. Though I had just came to discover another reason where it became vital. Thanks to Vladan as he brought it to my attention when he commented on my previous post:  VMware ESX 4 Reclaiming Thin Provisioned disk Unused Space

Yes, you will require storage VMotion in VMware ESX 4 to be able to reclaim Thin Provisioned disk unused space without downtime. As this is not a documented use of VMware Storage VMotion any where in the VMware Documentation I thought I will share it with all of you. If you had seen my earlier post VMware ESX 4 Reclaiming Thin Provisioned disk Unused Space, you will find out that you need to use Storage VMotion to reclaim thin provisioned unused disk space. Ok, there is other ways to reclaim Thin Provisioned disk unused space, but these require downtime. Below are one alternatives to VMware Storage VMotion to reclaim Thin Provisioned disk unused space, but remember it will require a downtime.

Follow up the same steps documented in my post VMware ESX 4 Reclaiming Thin Provisioned disk Unused Space, till you reach the Storage VMotion step then follow the below procedure:

1- Shutdown the Virtual Machine after you had run the sdelete on it.
2- Migrate the Virtual Machine to another VMFS datastore.
3- Power on the Virtual Machine.

Guess what being able to reclaim Thin Provisioned disks in some firms can save much more money on the disk cost to that would be spent on upgrading the VMware vSphere to a version where VMware Storage vMotion is included. I hope this help some one, & please leave a comment if you have any other way which does not require downtime nor storage VMotion as I could not find one yet.


  1. I have to disagree with this post. First and foremost, a VM that has rapid shifts up and down in disk space utilization should NOT be thin provisioned at the VMFS level to begin with. Thin at the SAN or thick – to prevent the LUN from being over committed and thus pause everything. Second, spending the money on a SAN feature license that covers all connected servers compared to the cost and constant changing “what this license includes” VMWare license makes it a no brainer – the SAN feature will be cheaper. Third – thick provisioning isn’t evil if you are dealing with less than 10tb. Disk is cheap, and you’re paying for the SANhead anyway, so don’t try to solve things with added licenses.

  2. Hi jt,

    I am not sure if I agree with you for the following reasons.

    1- Many of the virtual machines space get flatten with temp data which you might needed only once & after that you never needed that space any more.

    2- In the case I have pointed to in point one in this reply, SAN Thin provisioning feature will not allow you to reclaim that space as it will see it being used.

    3- Who said disk space is cheap, specially on high end storage.

    4- Thin provision on some storage vendors get to be quite expensive & some of them does not even support it.

    In the end, everyone has his way of doing things.


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  2. […] and has no Microsoft Clusters in place, then this can be easy and dandy with features like VMware Storage VMotion(ah sorry Only VMware offer such a feature at the moment, but that is not our topic for the day. […]

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