Tape backups have their place in many organizations, mostly large corporations. Sometimes their use is required directly or indirectly by law.
For all other organizations who are free to choose the “best fit” we put together a couple of things to consider when planning to invest in tape backup infrastructure:
Tape drives are expensive. Usually tape backup drives cost well over $1,500
Tape media is small and expensive. For example a 1TB tape today (2014) costs about $180. Which is 18 cents per GB
If your backup tape drive breaks in 15 years, will you be able to find a replacement that can read those tapes easily and quickly? Let’s not forget those are mechanic drives and prone to mechanic failure.
Tape needs to be wound and rewound. Those old enough to have used music cassette tapes will vividly remember how time consuming “random access” (aka seek) can be. Hence, tape will give you useful transfer speeds only if it isn’t necessary to fast forward and rewind all the time. However, most data recoveries aren’t full recoveries where you would profit from a huge and long contiguous block read operation. Most data recoveries are random access, such as your boss telling you “find file X or folder Y from last month and email me a copy within the next hour.”
Small tapes equals more tapes. Unless you have a great tape management system to tell you where the file is you’re looking for, it’s going to take a while to determine which tape has which files on it.
Tapes are also sensitive to magnetic fields and condensation (for example when exposed to hot/humid or cold climates)
Remember in the old days how hard it was to fit enough songs on a single music cassette? You wouldn’t want half the song on one tape and the other half on the next tape. However with data backups, and tape having limited capacities it’s not unusual to have a”half here and half there” situation.
Transfer speeds: HP states a top transfer speed of 108GB/hour. They quote it per hour to make you feel it’s super fast. Bring it down to MB/sec and you realize it’s only 30MB/sec. Not really impressive when compared to other media. A 10 year old USB 2 hard drive can do better than that.
Hyper-V Backups to Tape Media
Due to the nature of tapes you’ll most likely get mediocre performance when restoring full virtual machine disk images.
When you need to use a Granular Restore operation, the issue is that tape needs to seek back and forth in order to find all file fragments. Unfortunately seek operations on tape are very slow; hence, if you go beyond the ‘single file restore’ scenario, you may be better off restoring an entire VM. If you use external or internal hard disks or a NAS device, seek time is minimal, such as in the 5 msec or less range.
There are lots of things we can state about tapes and about alternative media, such as external hard drives.
At the end it’s your decision. Hopefully this article added offered some helpful info to your decision making process.