The Nectar Cloud is organised in Availability Zones, that are hosted by the participating institutions. An availability zone is a virtual area in the cloud where your VM will reside. In many cloud usage scenarios you won't need to worry about these: the Nectar software will select a suitable Availability Zone for you when you launch your VM. In certain other scenarios, however, you have to select the AZ that is right for your purpose.
How to select an Availability Zone at launch
You can select a specific Availability Zone for your VM at Launch time in the Launch Dialog's Availability Zone. The default option is "Any availability zone". If you leave this selected Nectar will find a suitable AZ for you.
If your VM uses persistent volume storage, your VM and your storage must be in compatible Availability Zones. You can find more information on the Introduction to Cloud Storage and Persistent Volume Storage pages.
In some scenarios you can use institutionally licensed software, in which case you may need to select the appropriate Availability Zone
Some participating institutions offer private availability zones, for which you may be eligible. You will have to contact your Node's local support.