If tape backup is an essential component of your disaster recovery strategy, then offsite tape archiving will often be as well. One of the classic tape backup risks is leaving the tapes onsite, where any disaster that wipes out your systems will do the same to your tapes. Basic disaster recovery strategy dictates that tapes need to be stored in a physically separate location. In that case, who is responsible for transporting them offsite; how are they stored in the offsite archive; who will bring them back onsite if disaster strikes, and how quickly?
Whether you choose to use a third party tape vaulting service or to organise this internally, service level agreements are the way to go, especially for the speed of return of the tapes for DR restoration. Your organisation will have a certain Maximum Tolerable Outage window (MTO) to recover before serious business impact occurs. Your tapes therefore need to be back on site, mounted and operational before that time period expires. This MTO along with how long the systems will take to be restored determines your SLA for offsite tape archiving. If you cannot get this guarantee on an internal basis, then the alternative is to subscribe to external tape vaulting services and negotiate the SLA you need and the price you can afford to mitigate the tape backup risks.
What else will it cost? Be prepared to deal with factors like the frequency of tape transport offsite, whether tapes are stored in racks or left in their transport containers and how fast you can get them back when you need them. Bear in mind also that in assessing tape backup risks, factors like the traffic between a remote tape archive location and your business (affecting speed of restoration) are uncontrollable. But other factors in offsite tape archiving can be controlled. Encrypting data that leaves the site is one example. After all, you want good DR restoration of your tapes for yourself, but you surely wouldn’t want anyone else see what’s on them.