There are two harddisk types in the CloudVPS Compute platform.
Boot disk: This is the harddisk that a cloud server is provisioned with and that will always remain with that virtual server. Unlike most other cloud services, at CloudVPS your boot disk is persistent, this means it will continue to exist even if the physical server that hosted the cloud server becomes permanently unavailable. In that case we will simply reboot your cloud server on a different machine.
The boot disk is ussually used for the operating system, and the relevant system and application software. It is often also used for the data of an application if there is no too much storage required. You can take an image from a boot disk that you can use to create new cloud servers from. The performance of a CloudVPS Compute boot disk is much higher than that of a normal hard drive, it is subject to a maximum number of IOPS that increases with its size. See our pricing page for more details.
Volumes: Volumes are harddisks that exist independent from any cloud servers and can be attached and re-attached to different instances at will. As volumes have a large size we recommend using volumes if you have a significant amount of data associated with your website or application. They can also be used for high IO applications. The maximum IO performance of volumes as measured in IOPS also increases with their size as is the case with the boot disk. This means larger volumes are able to achieve a much higher IO performance than the boot disk.
It it possible to make images from volumes and you can take snapshots and copy's of volumes as well.
Pricing and IO details
See our pricing page for more details on the different prices and IOPS limits of boot disks and volumes, als wel as the cost of images and snapshots.
It is not possible within CloudVPS Compute to scale down harddisks. The only way to downgrade a disksize is to create a new, smaller volume and then copy the data to the newly created disk.
Images (Boot disk and volumes)
Images are snapshots that are stored in our object store. Images are a bit slower to use than snapshots but their advantage is that you can use images to create new volumes and servers in different availability zones. They can also be used for disaster protection since they are stored on a different medium than the volumes themselves.
Volume Snaphot (Volumes only)
Snapshots are instant copies of your virtual server that are kept on the same storage medium as the base volume. We recommend using them if you need to take a quick backup to have the possibitlity to restore the server to its previous state.
If you want a copy of your volume you can instantly work with you can create a new volume that is a copy of the previous one. You also need to use this procedure if you want to increase the size of the volume.
As all the actions described here will actually use an instant snapshot of the virtual server in its then current state, CloudVPS does not guarantee the integrity of any active medium like a database when these techniques are used on a running cloud server.