Manual coalesce for a VM

[olivierlambert]

See https://docs.xenserver.com/en-us/xenserver/8/storage/manage.html#reclaim-space-by-using-the-offline-coalesce-tool

In Advanced view, a "Manual coalesce" button that will show a popup "The VM will be suspended during the operation".

Then:

1. Suspend the VM
2. Start the command
3. Unsuspend when finished

[julien-f]

@olivierlambert: @Wescoeur and @Nambrok think it's a bad idea to expose this feature to the user.

Related to zammad#31426

[Wescoeur]

The coalesce-leaf plugin has many limitations:

• Can only be called on LVM SRs.
• Can only be run on a VHD chain length of 2.
• No start/resume should be executed during forced coalesce execution. There is no security guaranteed by this script.

[julien-f]

@Wescoeur How does the plugin behave if the conditions are not fulfilled?

What should we do?

• remove the button entirely?
• add a confirm modal to indicate limitations?
• only allow the action in XO if the conditions are fulfilled? (something I'm not fond of)