Wednesday, August 18, 2010

Expanding VMFS datastore

A customer called today and wanted to know if they could expand their VMFS datastore which lives on Hitachi HDP (Hitachi Dynamic Provisioning) LUNs. I know this is possible, but until I've done it myself I can't just say "sure, go for it" when it comes to their production platform. Fortunately at Lumenate, we have an extensive lab environment so this was pretty easy to knock out of the park.

First, see that we have a 5GB (4.75GB formatted) LUN in our environment (pictures cropped to save space).
I take the liberty of expanding the storage on the array. I did not capture this because it may be different for your storage vendor of choice. In my environment, vSphere picked up the LUN size change.

Select the datastore to expand, right click and go to properties.
Click the Increase button near the middle top of the dialog box.

Now we want to select the LUN that our datastore is on. In this case, LUN 0. Note the informational message at the bottom of the dialog box. "The datastore already occupies one or more extents on this device. Selecting one of these extents on the device will expand it in the datastore. Selecting anything else on the device will add a new extent to the datastore."
Select Next at the bottom to continue.

Note here that we have our 5GB primary partition which is formatted as VMFS, and we're going to use the adjacent free space to expand the VMFS volume.
If this is what you want, go ahead and select next.

We need to tell vSphere how large to expand the datastore.
Take a minute to verify our work. Here I checking that I still have the right 5GB datastore, and that I'm expanding to the full capacity of the presented LUN.
Selecting finish at this step commits the changes.

The expansion happens quickly in this case, and completed by the time I got the screen shot ready. You should see some messages like this in your Tasks view.
Now I want to see my expanded datastore in my storage view, and verify that it was grown vs. having an extent added to it.

Happy Expanding!



  1. What version of ESX/vSphere are you running?

    Very cool feature you guys have added to the blog!! Love the new improved content.

  2. This comment has been removed by the author.

  3. Steve,

    Thanks for the question!

    We're running vCenter (had vSphere in my first reply) 4.1.0 build 258902, running ESX 4.1.0 build 260247, utilizing VMFS version 3.33. As I understand the VMFS grow feature started in vSphere 4.0. I will see if we still have an older test cluster running, and validate.