We have a netgear readynas pro with 6 drives. It's configured using netgear's X-RAID2 format, which is (I think) similar to RAID 5. The NAS is almost completely full, and needs to be cleaned up and archived, so we are asking our lab members to copy all their data off the drive and archive what they aren't actively using.
We're then going to back up the NAS and wipe it, and let people put the data they are still actively using back on.
Instead of copying the data from the NAS onto drives (using e.g. rsync), I am wondering if I can just label the drives and put them in a box, then install new drives in the NAS. This would also allow us to expand the capacity, and I would hope that if we needed to access the old data, we could just put the old drives back in a readynas shell.
My concern is I don't know how sensitive this would be to "something changing" Could we put the disks back in any readynas pro shell, or would it have to be the one we originally took them out of? If we updated the firmware, would this prevent us from accessing the data again?
Personally, I wouldn't trust hard disk drives for any type of long-term archiving. The "something changing" concern is certainly reasonable, but I'd also be concerned that hard disk drives aren't designed to be a long-term archival storage medium.
If I was going to archive data on disks I would want the data stored in the least-proprietary format possible. Something like a simple ext3 volume would make me reasonably comfortable that I would be able to read it in the future. I'd also make two copies, store them in different locations, and plan on making copies onto new media 2 or 3 years down the road.
If you are going to take the existing drives and "put them in a box", then I strongly urge you to also store the NAS device with them. The problem with proprietary RAID solutions is that there's no guarantee that future devices will be backward compatible with the format used on your particular drives. Let's say 5-10 years from now, when your NAS device dies and you replace it, will your new device be able to read your old boxed drives? Who knows?
Furthermore, what are you going to do tomorrow if you discover that---oh, crap!---we need to get something off our old NAS drives! Are you going to shut down the existing NAS array in order to load the old drives to do the restore, and thus create downtime for users of the existing array? Not good.
In summary, if you do need to keep a backup, it is probably best to put it on media that are specifically designed for long-term backup/archive. These days, that means tape. If tape is too expensive or otherwise infeasible, then the next best thing is probably to box up the entire array---device and drives together---and store them in a cool, dry place.