VMware Max Drive Limit

crawfordit used Ask the Experts™
I have a host server that has over 400 gigs of drive space. I am running ESXi 4.1.

When I config a guest os it will only let me use 256gigs of the data store. I can not add more during this process.

Will the guest os dynamically grow. As consumption of drive space is used up. If I could I would love to use as much drive space and possible.

So what I would love to happen is as more space is used will the software allocate more date store space to the guest OS.

If this is not the case what would be a good solution because 256 gigs is not going to cut it.
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Top Expert 2010
Your datastore that you're configuring VMDKs (virtual disks) on has a default Block Size of 1MB, which only allows a 256GB max VMDK. You can create a larger VMDK by removing the datastore, then re-adding it configuring a larger (2MB) block size which allows a max of 512GB VMDK.

4MB block size = 1TB VMDK
8MB block size = 2TB VMDK

Top Expert 2010

***Before removing your datastore, you will need to backup the data/VMs on the datastore as removing your DS will wipe it (i.e. delete data off of it). Re-adding the DS also reformats it (and thus wipes it). Once re-added, you can copy your data back to your datastore.

Top Expert 2010

So, to answer your final question in detail:
1. Backup/remove data/VMs off this particular datastore
2. Remove the datastore (rt-click on it and select Remove/Delete)
3. Go to Config tab -> Storage - Add Storage link to re-add the datastore
4. During the end of the wizard, make sure you change the block size to 4MB (since this is only a 400GB DS, making a larger block size is irrelevant)
6. Add VMs to Inventory if needed (see below)
7. You can then create a VMDK larger than 256GB & assign it to your VM.
NOTE: If you had VMs on this DS and copied them off; you can copy them back. Once done copying back, rt-click on the DS -> Browse DS, then go into each VM folder, rt-click on the .vmx file and select 'Add to Inventory' to have your VMs re-show back up in the left inventory pane/tree of your vSphere Client under your Host or Cluster or Datacenter.

Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017
this is because you have defined the default 1MB block size.

Change the block size and you can create virtual disks up to a max of 2TB-512bytes

• 1MB block size – 256GB maximum file size
• 2MB block size – 512GB maximum file size
• 4MB block size – 1024GB maximum file size
• 8MB block size – 2048GB maximum file size

Changing the block size, requires you to destroy the current VMFS datastore, and creating a new datastore with the correct Block Size above.

Configuration Maximums for VMware vSphere 4.1

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