Is using a NAS with hot swap disks an effective way of cycling backups?

We are looking at improving our backup solution. We don't have a huge amount of data to back up (currently ~500GB) which is backed up nightly onto an external HD. We have 3 of these HD, with one going in the firesafe on a weekly basis, and the other 2 rotating each night, so that the latest backup goes offsite overnight. The external HD are reaching capacity though, hence looking to upgrade.

There are a number of options that we could potentially utilise. I like the idea of a NAS server, with a 2TB drive. The size will allow future growth, without spending a huge amount. I'd like to get a second 2TB disk, and then swap this with a disk in the NAS on a daily basis. This is working on the assumption that the NAS has hot-swap disks, and so does not require powering down to swap a disk. My query is whether this is an effective way of using the NAS, or whether it will cause any problems with the NAS.

Another option is that we have a RAID 1 in the NAS, and swap out a disk daily, I'm just wondering how efficient that would be, as effectively the RAID1 array will be re-built on a daily basis, and I'm not sure how onerous this will be on the disks.

Solution 1:

Just because you can hot-swap a disk doesn't mean you should. The backplane and connectors aren't likely designed for large numbers of insertions / removals and the mechanical stress alone is probably going to create reliability problems for you. That alone would dissuade me from doing what you're trying to do.

Having only two or three generations of backup seems problematic to me. Having a larger number of medias is advantageous because you get more redundancy in the event of media failure. As inexpensive as hard disk drives are I'd look at expanding the pool of medias.

Personally, I'd buy more and larger external hard disk drives and keep doing what you're doing. You can get more mileage out of that solution by using something like rdiff-backup (or many other tools that do similar things) to store additional generations of backup on the disks and to alleviate re-copying bits that haven't changed.