In addition to the hosts, CloudStack’s Secondary Storage VM mounts and writes to secondary storage.

Submissions to secondary storage go through the Secondary Storage VM. The Secondary Storage VM can retrieve templates and ISO images from URLs using a variety of protocols.

The secondary storage VM provides a background task that takes care of a variety of secondary storage activities: downloading a new template to a Zone, copying templates between Zones, and snapshot backups.

The administrator can log in to the secondary storage VM if needed.