Over the past few years, we’ve written several blog posts about various disaster recovery methods for your applications running atop of Cloud-A’s infrastructure. If you take a look at these various articles, which highlight software and tools to help you achieve your disaster recovery requirements, you’ll notice that there there is more than one way to skin this cat.
The method you use to backup and recover your applications and data should vary depending on the technical requirements of a given application and/or data store and your organization’s tolerance for downtime for that app or data store.
Let’s dig into three conceptual models for disaster recovery on Cloud-A. We’ve ranked these methods 1-5 by data resiliency, time to recover and cost.
Today’s post is not to be confused with our post from back in May titled: “Backups With Snapshots” in fact, think of this as an extension of it. Snapshots provide you with a point in time image of your server which gives you system redundancy as you can easily and quickly spin up a new instance based on any of your saved snapshots. With all of that said, there are a few things to consider when using snapshots of your server as your sole backup process.
The server that is being snapshotted will be paused temporarily during the snapshot process. While this pause time can be minimal, it might not be ideal for a server providing mission critical services. Because a snapshot of an server instance includes the whole system (operating system and data) the process can take between 1 and 10 minutes to complete depending on the total consumed disk space of the server instance before your server is resumed.
There is a cost associated with storing server snapshots. Server snapshots cost $0.15 per GB per month, billed for as long as the snapshot exists. You will only be charged for the compressed size of your snapshot — not the provisioned disk size.
Solution: Volume Snapshots
If the downtime and cost of server snapshots is not ideal for your application, the answer might just be using volumes and volume snapshots.
With this method we recommend that users keep their operating system on the original disk space that is included with the instance and use volumes to store their data. This allows you to take snapshots of your volume for backups of critical data, rather than the entire instance, and avoid the downtime associated with server snapshots.
In the case of a server instance requiring restoration, your recovery is as easy as deleting the server instance, launching a new server instance, and mounting the last successful volume snapshot to it.
Another effective use case is when data is accidentally deleted by a user. You have the ability to mount a previous volume snapshot to a temporary server instance, recover the deleted data and migrate it back to the production server.
If you wanted to go a step further, you can continue to store a single snapshot of your standard image, so in a case of a server issue, you will be able to launch a new instance based on your image with all of your system preferences and server roles intact.
The nicest thing about volume snapshots? They are free! Cloud-A does not charge for the storage of any volume snapshots, making them a cost effective backup solution.
Since there is no cost to storing volume snapshots with Cloud-A, you can store as many old volume snapshots as you would like. As the snapshots begin to pile up, properly labeling them will become increasingly important so that you know which snapshot is which.
The frequency of how often you snapshot your volumes is dependant on your organization’s tolerance for data loss and/or downtime. An organization with zero tolerance for downtime might require a daily snapshot of their server volume to provide them with several point in time instances of that volume. A less mission critical server volume, like a test environment, or an organization with a greater tolerance for downtime, may only require weekly snapshots.
We have partners and customers who are using a number of different backup methods with our infrastructure today. This really speaks to the flexibility Cloud-A’s Infrastructure-as-a-service offering. At the end of the day, the best backup processes are the ones that are recoverable and volume snapshots provide you with a cost effective, recoverable backup solution. We urge you to test it out for yourself!