As the cost of drive space falls year after year, pushing down the cost of offsite backup, it makes sense to have an offsite backup solution as part of your disaster recovery plan. But it might not be a wise choice to make offsite backup your only solution, especially if you have some big files that need to be backed up regularly.

Offsite backup works great when you need to back up simple files, such as documents and pictures. But things are less straightforward when it comes to complicated files, such as large PST (Outlook email files) or SQL databases. Backing up big PST files, especially when they’re left open frequently, may be a problem. And in most cases, backing up a SQL database may involve a more advanced application that can manage the transaction logs and general open-file concept of the database. In addition to these complications with open files, there is the length of time that it takes to back up big files. Sometimes the process can take all night—or even longer. And when a file is constantly being used, doing a proper backup gets complicated.

There are the complexities of recovery to consider as well. To actually recover a large PST file, you have to download it from the offsite backup. This can take several hours or more, and that might not be acceptable in a disaster-recovery situation.

For these reasons, it remains a good strategy to have a local backup—for example, to an external hard drive. Recovery will be a snap, and you’ll have the peace of mind of always knowing that you have a second backup.