The Planet Blog

More often than not, server backups are misunderstood. With dozens of hardware options and hundreds of software options, finding the right backup can be intimidating. To assuage some of those fears and clear up a bit of that confusion, let’s go over a few of the most common backup schemes. This list isn’t all-inclusive, and the options presented shouldn’t be mistaken for backup plans. A backup scheme is simply a method of creating backups. A backup plan (or disaster recovery plan) is a scheduled implementation of a backup scheme. As we evaluate each scheme, we’ll look at the requirements, costs and benefits, and by the end of our tour, you can decide which best fits your business.

Before we get too far into the specifics of the different schemes, we should define some fundamental terms that we’ll use throughout the comparison:

• An archive is a set of data that is being preserved
• A reference point is a single archive against which comparisons are made
• A restore point is the most recent working backup

The key question a backup scheme answers is this: “If a server suffers a catastrophic failure, what is needed to resume operations with minimal downtime and data loss?” Again, the backup scheme is not a complete disaster recovery plan — its focus is the restoration of data.

The four basic backup schemes we’ll compare are full-server backups, simple incremental backups, multi-level incremental backups and differential incremental backups. The primary considerations about the method that should be used are the server load generated by the backup process, the backup file size, and the speed with which a backup can be restored.

Full Server Backups

A full server backup is one of the simplest methods for a backup scheme. It takes only a single backup archive to create a restore point, which makes data restoration simple and fast. The drawbacks are the amount of time it takes to make the backup, the load it generates, and the total size of the backup. Each backup scheme we’re comparing uses a full backup of the server.

As we evaluate the other schemes, you’ll note they all start with a full backup as a reference point, and create their own restore points as they move forward.

Simple Incremental Backups

A simple incremental backup attempts to resolve some of the issues with full backups, and it does a good job. With an incremental backup, a single full backup is made that serves as both a restore point and the initial reference point. On subsequent backups, it becomes a little more complex. Instead of making a new full backup when it is updated, this scheme compares the current state of the server against the state of the server as it was in the reference point (the first full backup). If it locates any changes, it backs up those changes and generates a new snapshot of the drive as another reference point. This new reference point is then used for the next incremental backup.

This backup structure means the restore point on a server with this backup will consist of the initial reference point and all subsequent incremental backups that use this reference point. This dependency is the primary weakness in simple incremental backups: All of the backups — from the original reference point to the incremental additions recording changes from the reference point — must be uncorrupted and complete for the backup to fully restore the data. If any backup is missing, corrupt or incomplete, the restoration can’t be completed.

The server load created and storage space required for this type of backup is generally less than what you’ll see in a full backup scheme, especially when there aren’t many differences between the backup point and the reference point. On the other side of the spectrum, if the entire data set changes between backups, the storage requirements and server load will be the same as they were when full backups were being performed.

There are two incremental backup schemes that attempt to address this issue: the differential and the multi-level incremental backup schemes. In Part II of “Know Thy Backups,” we’ll explain the pros and cons of these methods, and you’ll be ready to plan your backup strategy.

-Ben

At The Planet, we’re excited about the holiday season. We’ve had a great year, so this is a perfect time to look back on 2007 and store away the memories much like one would store server backups in our data centers. How’s that that for a convenient segue into a discussion about The Planet’s backup solutions?

We currently offer NAS, DiskSync, Dedicated SAN and Dedicated Backup Server options, and as the resident backup and storage guru on the Product Management team, I love sharing backup knowledge with our customers. What question do I get most often? Easy: What is the difference between

What is the difference between NAS, DiskSync and the Dedicated Backup Server?

NAS (Network Attached Storage) is storage space allows you access over FTP. You write or provide the software to create and send backups to your NAS, and it functions as a reliable external disk to protect your data and store information separate from your server. Think of it as a target disc, albeit a pretty small one. You can buy NAS space from The Planet in increments ranging from 20GB to 200GB, and our typical NAS setup accommodates many users on each of our available NAS devices.

Our DiskSync product offers a much more complete SAN (Storage Area Network) infrastructure backup solution with the ability to schedule full backups and perform restores in our managed environment. Rather than having to create the backup software, our DiskSync solution enables you to quickly and easily monitor and track your data backups. On the infrastructure side, we host the large storage network and maintain the integrity of all DiskSync user data. The SAN structure is significantly larger than a NAS device and is much more scalable. It’s able to accommodate a considerably higher number of DiskSync users and any additional space you may want or need. DiskSync backups are available in 10GB increments with unlimited capacity.

With our new Dedicated Backup Server (DBS) solution, you become the admin for the entire system. You get a dedicated server with the R1Soft CDP Server software/license installed, and full root access. You have the ability to manage backups and delegate authority to users and sub-users, and you manage the OS, which allows for true customization for any of your more complex backup needs. We’ve found that many customers want this complete control and the peace of mind that each DBS is individually encrypted for data security since no other users access your DBS. Our most popular Dedicated Backup Servers come equipped with 500GB, 1TB and 1.5TB of data, but we’re always open to a challenge if you need more.

While that’s a quick rundown of our three main backup solutions, it succinctly explains a few of the key differences I like to communicate when asked to run through the options. We feel this array of products can meet the needs of almost any user, so if you have additional questions about backup solution implementation or if you would just like a little more information, visit our Backup page or post a quick comment to let me know.

-Brett