Tape Backups: They’re No Longer Enough
After reading this blog article from eWeek a few days ago, I was again reminded of the fact that many folks are still trusting tape backup to secure their business data. Backing up to tape was the gold standard for many years, and is better than having no solution in place, but it has been surpassed in the last 10 years with the developement of bit-level or block-level backup technologies.
More modern backup solutions decrease the amount of time it takes to backup your data (backup window), allow for much faster restoration when needed (recovery time objective), usually send data offsite automatically (no more changing tapes and carrying them offsite), and most allow for instant virtualization of a failed server in the event of a catastrophic loss to your physical hardware. Also, tape backups (file-level backups) can only backup your data. Block-level backups backup your entire server — the operating system, applications, etc. In the event you have a server loss and need to recover from tape, you must first re-install the operating system and aplications before you can think about recovering the data from the tapes. 
With block-level backups you can recover it all, usually in a matter of an hour or so. Tapes are also notorious for going bad. Unfortunately you often don’t find this out until you need to restore from one, and then its too late.
Block- and file-level backups differ because the software that performs block-level backups goes “deeper” than just the files and folders. Instead it backs up the underlying file system, or the actual “blocks” on the disk. It has also been referred to as “continuous data protection” or “image-based backups.”
Different software vendors may perform the task differently, but they all manage to perform the same basic task. Some examples of block-level backup software are Axcient, Datto, Acronis among others.
The main benefit to using block-level backups over file-level is that it can save space and time when backing up and restoring files and even entire servers.
- The first time a backup for a system is performed, it grabs the entire selection list, or whatever list of system volumes you choose for a given system. This is known as the “base” backup.
- The next scheduled backup looks for differences in the file system and only backs up the changes. This is also known as the “incremental” backup.
- It can then combine the two backups into one backup set. This process is known as the “condense” or “collapse” job and creates a “synthetic full” backup.
There is a lot more detail to the actual inner workings of this, but these are the basic points. The benefits of this method include the fact that only the changed blocks are backed up, which saves space, and full-server restorations are quicker and easier since it only has to write blocks back to the disk rather than individual files and folders.
Yes, tapes used to be the best solution available for backups. But then again before email, the post office used to be the best way to get a note to someone as well!
