System Disk and Data Disk FAQ
Explaining the System Disk and Data Disk Architecture
Some Cloud Servers use an architecture that pairs a system disk with a separate data disk(s). The benefits of implementing this architecture include improved provisioning times, as well as more flexibility for local data storage and disaster recovery. Server images don't include data disks, but they will include local system disks. This means that you will need to use a separate method for saving information located on the data disk(s).
Saving Your Configuration Using System Images
You can retain the operating system and configuration information from your system disk by using our Cloud Servers imaging feature, but it will not save any information from the data disk(s). To save your data disk(s) you have the option of using Rackspace Cloud Backup, which is a granular file level backup system that you can configure to save only the files and folders you wish to keep.
How Do I Back up a Data Disk?
Since system images will only save data from the system disk, you will need to use a backup solution like the Rackspace Cloud Backup service to retain information from the data disk(s)..
What About Scaling and Resizing?
Only first-generation and standard servers can be directly resized. Other servers can be scaled by either hosting your application on a load-balanced cluster (horizontal scaling) or by recreating the server with a different server flavor.
Horizontal scaling is the most flexible approach, but it requires that your application be able to work in a clustered environment. With horizontal scaling in place you can add and remove servers on demand, either manually or with our Auto Scale features.
To recreate the server you can take an image of your server and build a new server with a different size, or migrate data to a new server using a tool like rsync. If you use a Cloud Block Storage volume as your server's boot device, you can also clone your boot volume and use the clone to create a new server (see Boot a server from a Cloud Block Storage volume). Note that the server IP address is not preserved with any of these approaches. If you require a persistent IP address, consider a load balancer or other proxying solution so the IP address is maintained separately from your application servers.
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