Some thoughts on Backups – Redundancy, RAID, Testing and Encryption

Tips on backup methods, redundancy, RAID, testing and encryption.

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Update May 28, 2014

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Original Post

Department of Redundancy Department Redux

Doing regular backups is an essential part of securing your data and preventing loss due to acts of nature, malice or accident. I currently do three different types of backups to make sure that my data is safe.

A. Automated backup of user files.  Full backups (i.e. cover all user files) are done weekly. Nightly backups are incremental (i.e. only cover files that changed that day). I use backuppc running on an Ubuntu Linux workstation/server for this task. The main advantage of this type of backup is that you set and forget it. If something happens and you lose a user file or folder due to an accidental overwrite or deletion it’s a simple matter to restore the file from the previous day. The main disadvantage is that you can only restore a file if the OS and backup software are working. If you have a hardware failure or the OS gets really scrambled then you’ll need to reload the OS and backup software before you can get access to your files again.

B. User file system snapshots. These are done every two to three weeks or if I’ve done a particularly large amount of work that I want to be sure to protect. I use Beyond Compare to mirror home directories to an external USB drive. I have a pool of several different drives that I use for this task and I alternate among them so that I always have some older mirrors for when something goes wrong. I also keep at least one drive off site so when the worst happens I still have a backup somewhere safe. The nice thing about this kind of backup is that you can access every file very easily just by plugging the drive into another computer.

C. Boot disk / OS partition images. I only do these as needed, like before a big hardware or OS upgrade or when I have found a particularly good setup of that I’d like to keep. I use PartedMagic to either copy the drive or image the relevant partitions. These kinds of backups make it easy to get backup and running if you have a disk crash or major virus problem since you don’t have to reload the OS and programs. The downside is that you can’t readily pull a single file from an image. You could however pull a single file from a cloned drive if necessary.

By now it should be clear that there are pros and cons to various backup strategies. The main point however is that the key to data security is redundancy. Whether you backup to tapes, USB drives or the cloud you should use more than one type of backup and make sure that you have copies important data off-site for when the worst happens. If you can’t easily transport and store USB drives in an alternative location you may want to consider a cloud service like Carbonite or even something as simple as Dropbox to make sure that your important data has spatial diversity.

RAID is not backup!

Some people have the mistaken idea that if they use RAID (Redundant Array of Inexpensive Disks) in their computer that they don’t have to be concerned with backups. RAID systems are designed to either enhance either the speed or the reliability of the disk system. RAID systems optimized for speed sacrifice reliability. RAID systems with enhanced reliability have less speed. RAID configurations optimized for reliability only protect against drive failures. They do not protect against data loss due to controller failures, viruses, malware, hacking, user errors or stupidity. In short, RAID is NOT a backup solution. For the record, I use an 8 disk RAID Level 6 system in my main file server. Six of the disks are live and two are hot spares ready for rebuild at the slightest hint of failure on any of the other drives. This is reassuring to me and gives me great confidence that the system will be available when I need it. I keep copies of all my files on the RAID server but I still back it up every night!

Test Your Backups

To be certain that your backups are going to be useful when the time comes it is important to test your backups periodically to make sure that the system is working properly. If you don’t confirm that the software and system is working ahead of time you could be sorely disappointed the day you have a major hardware failure or virus infestation. I suggest putting a monthly recurring task in your calendar to check your backups.

If your backup is a simple file snapshot to a USB drive or a cloud service like Dropbox you can test the backup by simply scrolling through the directory tree and opening random files to make sure they are there and not corrupted. If you are using an automated program like backuppc you should check the log reports for errors and inspect the directory trees to make sure that your backups are getting the specified files on the specified schedule. You should also do sample restore operations and check the restored files. Be careful that you restore the files in such a way that you don’t overwrite existing or newer files. If you are cloning drives you should confirm that the cloned drive boots and runs properly before doing a hardware or OS upgrade on the original drive. Similarly, if you are making a drive image it is a good idea to test both the software and your ability to use it properly. You do this by creating the image, restoring it to a spare drive and then testing said drive.

Encrypt Your Backups

I didn’t mention it above, but all of my backups are done to encrypted hard drives. It makes no sense to backup an encrypted hard drive to unencrypted media. If you are not yet using encryption on all of your drives and backup media you need to get with the program now! Do it before it’s too late. If you’re on Windows you can encrypt on the fly using TrueCrypt. Download it and get started. It’s free! Encryption for Mac and Linux is built into the OS. Learn how to use it! Unencrypted drives and backup media are security risks so make it a point to either encrypt or wipe old hard drives and media.


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