Introduction to VM disk file sizes

When you launch a virtual machine, the hypervisor or public cloud region will deploy one or more VM disk files. To launch a VM, most hypervisors require the disk size, and this article describes how to get the size from the command line with some popular virtualization tools.

 

The capacity of a VM disk file is the correct size of the disk when it is running on a hypervisor.

  • For fixed disk formats, the capacity is the same as the physical size of the disk image.
  • For sparse and compressed formats, such as stream-optimized, it is the provisioned size.

Enter the capacity of the VM template in the multi-cloud platform

When you upload an OVA to the self-service catalog of the Abiquo cloud platform, it will automatically enter the capacity in the VM template and display it for your users.

But when you upload a single disk file via the UI, then you must manually enter the capacity, which is a value in bytes.

Remember that the capacity will depend on the type of disk:

  • For fixed disk formats, use the physical size of the disk image.
  • For sparse and compressed formats, use the provisioned size.

If you are have an OVF file to manually upload a template, it must have a correct ovf:capacity attribute. For example, here is an extract of an OVF file.

<Info>List of the virtual disks used in the package</Info>
<Disk ovf:capacity="734003200" ovf:diskId="vmdisk1" ovf:fileRef="file1" ...
 

If you are uploading a single disk manually, you must enter the capacity but if you don’t know the correct size at that time, you can always enter a best-guess value. Then before you create a VM, edit the VM template and enter the correct value.

 

 

Screenshots: Creating a VM template catalog in the Abiquo multi-cloud platform

 

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Enter the capacity of the VM template in the multi-cloud platform

When you upload an OVA to the self-service catalog of the Abiquo cloud platform, it will automatically enter the capacity in the VM template and display it for your users.

But when you upload a single disk file via the UI, then you must manually enter the capacity, which is a value in bytes.

Remember that the capacity will depend on the type of disk:

  • For fixed disk formats, use the physical size of the disk image.
  • For sparse and compressed formats, use the provisioned size.

If you are have an OVF file to manually upload a template, it must have a correct ovf:capacity attribute. For example, here is an extract of an OVF file.

<Info>List of the virtual disks used in the package</Info>
<Disk ovf:capacity="734003200" ovf:diskId="vmdisk1" ovf:fileRef="file1" ...
 

If you are uploading a single disk manually, you must enter the capacity but if you don’t know the correct size at that time, you can always enter a best-guess value. Then before you create a VM, edit the VM template and enter the correct value.

 

 

Screenshots: Creating a VM template catalog in the Abiquo multi-cloud platform

 

Manually upload a VM disk to the cloud platform to create a VM template with the Disk from local file option

You can edit a VM template disk to change the capacity to a correct value

The administrator maintains a template catalog to give users self-service access to VMs