How do I ensure data integrity of ISO images?

Question

I want to create a long-term data archive of old stuff I don't need daily, but don't want to throw away either (e.g. all raw data of my thesis work). Optical media have failed me too often in the past, so now I am using an external USB disk and - to protect against accidental modification of the archive - I create ISO images of data batches and store these (and mount them on demand). The harddisk is NTFS formatted for portability (read/write for Linux and Windows, and at least readable for Macs).

My question is: Are ISO images on external harddisks a good idea for long-term archiving data? How about bad disk sectors? It sure sounds easier for the OS to fsck a disk with 200 ISO images instead of 2,000,000 separate files, but is it? Should bad disk sectors be my primary worry when thinking about long term archives?

Any ideas - or alternatives - for an affordable long-term data storage concept would be appreciated.

Answer 1

You can use ISO image files, however they are neither very efficient nor in any way reliable. So the advantage of direct mount is only limited.

Maybe you need to combine both - store the ISOs in larger redundant archives (like http://en.wikipedia.org/wiki/Parchive) and then unpack them on demand (or just keep multiple copies, but then you should check and re-copy them regularly).

Answer 2

First of all this question should be on SuperUser.

Nevertheless you strategy is is pretty solid. I would use disks in raid for added protection.

I you want to make sure the isos haven't changed you can take their md5sum when you store them and compare it to their md5sum when you retreive them.