How to estimate the lifespan of backup tape media

What is a good rule of thumb for how long a backup tape will last before you start running into errors?

When it comes to estimating the useful lifespan of a piece of backup tape media, there are a number of factors that must be considered. The first consideration is how often the media will be used. LTO tapes for example, often have an estimated shelf life of 30 years. However, shelf life and active life are two very different things.

For example, if a tape is being used for long-term archiving, it may be written to once and then sit idle for years at a time without use. But if a tape is in an active backup rotation, it may be written to frequently over a short period of time, increasing the amount of wear and tear on the backup tape media.

It is not uncommon for tapes to be used in an active backup rotation for some period of their life before being relegated to long-term archive duty, so it is important to consider how a particular tape has been used when estimating its lifespan. Many organizations report that they are able to read or write to backup tapes at least 250 times before the media will begin to produce errors consistently.

Although 250 uses over 30 years could be considered to be a good starting point for some types of tapes, it is very important for each organization to monitor their backup logs for tape errors. Tape life expectancy varies widely from one organization to the next because of a number of factors.

Temperature and humidity play a huge role in a tape's life expectancy. Tape vendors list very specific environmental recommendations, and deviating from those recommendations can dramatically shorten a tape's life. Similarly, the amount of time that a tape spends in the tape drive impacts tape life because when a tape is in a drive, the tape's protective cover is open, thereby exposing the tape to dust and other contaminants.