Disk Versus Tape Discussion

Let's examine some of the backup methodologies used by many of the backup software vendors today. Keep in mind that a lot of backup software in the market today was designed to use a tape drive and tapes as the backup equipment and media. The purpose of this discussion is to look at the backup and restore process. When we reference tape-based software, we are referring to backup software that can store to either tape or disk, but the design process is inevitably linked to the requirements and limitations of tape systems.

Although many of these software vendors advertise that their tape-based backup programs can also store their backup data on hard drives, these programs still utilize a "tape-based" approach to both the backup and restore process.

The Tape Based Approach

Because the only way to store data on tape requires a linear process, the tape-based backup software tends to follow this linear line of thinking. Even when tape based backup software uses a hard drive, it does not take full advantage of the disk-based random access storage process. As a result, when tape-based backup software uses disk-based media, it views the hard drive as a "tape simulator" in that it still uses the same linear storage process.

Traditional tape based backup software divides the backup process into the following tasks:

Baseline Backup - The process of backing up ALL of the files on the computer, in their entirety. Baseline backups take the greatest amount of time and storage because every file needs to be backed up and each baseline backup starts over from scratch and does not reference and previous backups that may have been performed.
Incremental Backup - The process of only backing up the files that have changed since the last backup. Typically incremental backups are very fast and do not require significant storage space. The goal of incremental backup is to reduce the time to perform the backup. The problem with incremental backup is that each additional incremental backup since the baseline, has to be "replayed" at the time of the restoration. As a result, when you need to restore a computer that has been backed up using an incremental backup system, you need ALL of the incremental backups (one at a time), in ORDER as they occurred.
Differential Backup – The process of only backing up files that have changed since the last BASELINE backup. The goal of differential backup is to reduce the time to restore by only applying the baseline backup plus one set of differential backup data. The problem with differential backup is that every day, each differential backup needs to backup everything that has changed since the baseline backup; this includes everything that has already been backed up since the baseline. In other words, each differential backup gets larger as more time lapses since the baseline backup.

Tape Based Restoration

Restoring data from a linear storage system takes time and puts a lot of work on YOU to make it successful. The tape-based restoration process assumes you have access to all past backup data without any break in sequence. Whether using tape or disk as the storage media, the tape-based backup approach puts the burden on you to manage, store and organize all your backup data to make the restoration successful.

The restore process for most tape-based backup software corresponds to the backup approach that was used. For example, let's assume you were using an incremental method of backup with a tape-based system. In order to restore your computer, you would have to first restore your baseline backup; then apply ALL of the incremental backups (one at a time), in ORDER as they occurred. Any break in sequence may result in an incomplete restoration. Now let's assume you were using a differential method of backup with a tape-based system and again, you need to restore your computer. You first need to restore your baseline backup and then, apply the most current differential backup. While the differential method saves time at restoration, it can be very inefficient at the time of backup because as more time passes since the baseline was performed, it takes more and more time to perform the differential backup.

The important point to keep in mind is that when you use tape-based backup software, you have to periodically re-baseline your data to make sure your restoration process is possible and reasonably efficient. The tape based software puts the burden on YOU to make it efficient and easier to use. Backup for Workgroups, with it's disk-based approach, makes it both backup and restoration EASY on YOU by making these processes straightforward, simple, and less time consuming.

Backup for Workgroups' Disk Based Approach

Backup for Workgroups is designed from scratch to use disk based media for storage, which allowed for a whole new approach to be implemented when in comes to both the backup and restore process. We call this approach "disk based," which refers to both the storage media used and the new fundamental design which is disk based as well.

How do you benefit from Backup for Workgroup's disk based approach? It eliminates WORK and makes backup and restore SIMPLE. How does it do this?

Eliminates the need for frequent re-baselining.
Backup for Workgroups uses what can be viewed as a "rolling baseline." The rolling baseline concept keeps the most current version of the files that have been backed up PLUS the most recent "N" number of revisions of these files. In this rolling baseline, you get to choose how many revisions of your files you want to keep. Backup for Workgroups maintains your most current revision plus the number of revisions that you choose and automatically purges old data providing you with space to backup new data. This rolling approach allows the backup process to continue along adding new data and purging old data, without compromising your ability to restore your entire computer or a group of files when needed.
Simplifies the restoration process.
Restoration is based on WHAT you want to restore, not HOW the backup was performed. With Backup for Workgroups, you select what you want to restore, and the software finds it for you. It does not need to apply baselines, incrementals or differentials because it can directly extract the precise version of the files you have selected to restore from the Backup Server in a random fashion, eliminating dependence on the linear restoration process required by tape based backup systems.
Eliminates need to make a choice between tape based approaches.
With Backup for Workgroups, it just works! You do not need to choose between "Should I use an incremental backup or a differential backup?" And, you also don't need to worry about how many days have gone by since your last baseline backup. Backup for Workgroups thinks about all of this for you; it backs up what changes on your hard drive, keeps the number of revisions that you want to keep, stores the data to a Backup Server for you so you can easily and freely gain access to any file at any time. It presents you with restoration options that match your data and the reason why you need to restore, rather than making you think about how to find your data inside all of those different backups!

In summary, the disk-based approach used by Backup for Workgroups makes it easy for you to quickly backup the files that need to be backed up and restore the files that need to be restored, without asking you to spend a lot of time maintaining the Backup for Workgroups system. It eliminates your reliance on tape media, the headaches that tape media can cause (can't find tape, tape not working, tape not compatible with replacement tape drive, etc.) and saves you money because you can use more cost-effective storage. It also simplifies the backup and restore process by eliminating the need to frequently perform re-baselines, eliminates need to make choice between what backup approach to use, and makes the restoration process faster and more straight-forward.