customize-vm-storage.markdown

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Editing Storage options of a template

Remember:

VMs are created by instantiating a template, which is where you specify which images the VM will need. Multiple VMs can share images (regardless of any templates that the VMs or images may be related to) only when the images are not persistent.

Storage for a VM is specified in terms of disks (which are images linked to templates). On the Storage tab of the template-editing screen, you can see two columns:

• on the left, the list of all disks already defined on that template
• on the right, the particularities for a disk selected from the left.

You can add as many disks as you need to a given template, each referring to an existing image or to a volatile disk.

NOTE:

When you import an appliance from the AppMarket, that action usually downloads one image along with a template, that relates to it. You can still personalise that template on this Storage tab of the template.

Edit a disk for a template

When you click on a disk of a template (on the left column of the Storage tab), or when you click on +, you will select that disk for editing (it will get a blue line on the left of its name and its options will show on the right column).

The options you have for a disk are:

• Image: to attach an existing image to the template you are editing
• Volatile Disk: to create a storage place on the fly whenever a VM is instantiated from the template you are editing. A practical usage is to add (arbitrarily big) extra scratch space to your VM, while keeping a basic core OS image that is easy to move around in the system.

Choosing an image as a disk in a template

When you select Image as the storage option for a disk in a template, you see a table where you get to choose the image you want from the list of your existing images. You can sort and filter that table to help you find the image you want to use. When you find the image you want and you click on it, its name will appear in blue under that table.

Choosing a volatile disk in a template

⚠ WARNING:

Volatile disks are only available as long as a VM is running with them attached, and everything stored on Volatile disks is lost once their associated VM is shut down.

Furthermore, volatile disks cannot be saved-as.

Make sure you understand these facts and, therefore, place in volatile disks only data that you are ready to loose after the VM is gone.

NOTE: By default all the projects get 10GB volatile quota. Please contact us if you need more quota than the default.

When you select Volatile Disk as the storage option for a disk in a template, you must specify the Size you want for the disk. You can also specify the combination of Type and/or Format.

NOTE:

It does not really matter what you choose for FS and Format, because you can format your drives via the operating system tools.

Deleting a disk from a template

Next to the name of each disk on the list of disks when editing a template, you can see a black (x) button. If you click on it, the disk will be removed from the template.

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NOTE on Advanced options:

The Advanced options that you can see on the screen are very specific ones that we do not use every day. If you think you need to use them, we recommend you try and learn about them on the official OpenNebula documentation (for example, here). And if you find benefits in using them, please send us an e-mail to let us know: [email protected].