raidisnotabackup/content/4.md

+++ title = "You've convinced me - so how do I back up?" description = "Backups are a contentions and complicated subject, but these simple rules should help guide you." weight = 4 type = "post" +++

• Always back up in some way. While a copy of the data on the same array won't protect you against all, or even very many, failure modes, it will protect you against some, and those are usually the most common. Remember that a backup on the same server is still susceptable to some of the same failures as the original data set, but having 2 copies is still better than 1.
• A good rule of thumb is three copies: the original (RAID or otherwise); one onsite copy on a different, preferrably offline, medium; and one offsite copy. Store the offsite copy in the cloud, a data vault, or at a friend's house; just keep it somewhere else. This is often called the "3-2-1" rule: 3 copies, 2 different media types, 1 offsite.
• Make backups regularly, at least once a week, preferrably more, and automate it! Forgetting to back something up and then needing just that backup a common scenario and is never fun, and the more frequently you back up, the better your recovery resolution, and back up regularly-changed files more often.
• Test your backups regularly, at least once a month; a backup is worthless if you can't restore from it. Just because you have a backup doesn't mean you're protected: always test them and fix any problems. If you never test your backup, you will almost certainly find it doesn't work, right when you need it.

There are dozens of backup utilities out there which work well; I'm not going to prosthelytize for any one of them, but I personally use BackupPC and plain old rsync for my server and workstation backups.

Only you can determine what you need to back up, and that differs for everyone. But if you can't replace a set of data, you should definitely back it up: Murphy's Law applies here as much as anywhere.