I get a lot of questions about what the benefits are of having a RAID array versus a backup solution. Often potential clients see them as redundant, but that is definitely not the case. I am going to briefly outline the pros and cons of each and explain why having both is your best bet.
RAID stands for Redundant Array of Independent (sometimes Inexpensive) Disks. There are a number of different types of RAID available. Right now the most common arrays that you will see are RAID 1, RAID 5, and RAID 10. The basic purpose of RAID is to provide redundancy, if one disk fails, the other drives essentially take over until the failed drive is replaced. RAID 1 and RAID 10 can both survive multiple drive failures, RAID 5 can survive a single disk failure. While redundancy is the main benefit of a RAID array, it is also one of the cons because in the case of data corruption, the corrupted data is written to all drives on the array.
Backups on the other hand protect against data corruption and loss, but don’t provide true redundancy. Here at INAP, you have a couple of options with backups, you can store them locally on a secondary or on one of our highly redundant backup servers. With backups I highly recommend doing daily incremental backups and weekly full backups. That is where my argument for separate backups in addition to the RAID array comes in. If data is corrupted on the RAID array the backups that were not affected by the corruption can be restored and you are back in business.
I highly recommend having both solutions in place. No matter where your server is hosted, hard drives fail, it is inevitable. When and how, and whether or not there will be any warning is harder to predict, data corruption is always a possibility. Having as much redundancy as possible is simply the best practice.
Updated: January 2019