The Unofficial Backup Admin's Handbook Part 5

Onsite and Offsite Storage

Alright, this is the beginning of where Backup and Recovery meets Disaster Recovery. Where is your data stored? Do you keep it in your datacenter? Your Office? Shipped to a Colo or a 3rd party storage? Replicated disk to disk? There are tons of options and they are determined by your company's needs and requirements.


Why would you keep your data onsite? Simplest reason would be speed of recovery. Having the data on location removes the need for shipping medium or transferring over a WAN connection of some sort.

This is used when you're less worried about a large scale failure such as a datacenter going dark, but more concerned with data corruption or disk failures. Data can be stored on any medium listed previously.


Distances less than 60 miles are generally not considered valid Disaster Recovery sites, but storage of medium at those locations are still valid for quick recall of medium and still reduces the risk of an environmental incident (flood/fire/power outage). Although not ideal, it's still better than having all your eggs in one basket so to speak.

Distances greater than 60 miles are generally considered viable disaster recovery sites and a good location for your backup data to be copied/transferred. This would provide the best environmental isolation for large scale events (think hurricanes or power grid outages). The largest drawback to shipping backups to a long distance DR site would be the time required to get the data back onsite.

Offsite, and what determines a valid Disaster Recovery location can vary greatly by region, cost constraints, regulatory restrictions, company requirements and the ability of people to reach their location to resume operations. This post isn't intended to recommend a distance as much as to remind personnel to keep distances in mind when determining where to store their data.

Mixed Onsite and Offsite

So we see that both Onsite and Offsite have Pros and Cons. The ideal approach would be to have a mixture of storage locations used. You may decide to keep a short retention on disks onsite and then copy longer retention backups to cheaper medium and have that medium shipped offsite to a long distance DR location for import if required. You could also have data replicated from your primary backup disks to an appliance offsite or even to a contracted cloud storage provider. The combinations are various and can be customized for your particular requirements.

Part 6: Backup Sources