On 12/30/19 7:47 AM, Martin Flynn via vcf-midatlantic wrote:

Would agree with Mark that the best plan is off-line hard disk storage.  Zip lock ESD bag, with desiccant, multiple physical copies in diverse locations.

I would augment that by making it a *set* of drives, stored in a block-checksumming filesystem like ZFS, and treat the set of drives as a unit. ZFS filesystems in particular can be "imported" and "exported" to/from a system as a unit, making this convenient.

BTW, If you can find them, best disk for long-term storage at the moment is the M-DISC.  Bought a large quantity in 2010, zero failures to date.

I've noticed a decrease in M-DISC availability lately. Do you have any idea of what's going on with that? I have some discs and a drive, and I've made archival backups of some irreplaceable stuff on those, but am nearly out of blanks and went looking recently...I don't see as many out there as I did a couple of years ago. -Dave -- Dave McGuire, AK4HZ New Kensington, PA

On 12/30/19 6:36 AM, Mark Whittington via vcf-midatlantic wrote:

Regarding DVD-R, it's my understanding that most (if not all) optical formats are susceptible to physical degradation. My current archival plan involves using external HDD's. Given that you can buy a 5TB USB 3.0 external drive for ~$140 and it will hold approximately 1000 4.7GB DVD-R's worth of data, it's economical as well as more reliable for long-term static storage.

If you look at the error rate specs and do the math on those drives, things don't look so good past 3TB or possibly 4TB. Bits WILL get flipped, you don't have to move very much data to see it happen, and there's nothing you can do about it. Remember, those drives are mostly being churned out for consumers to store movies and huge video games on...where a flipped bit here and there might result in one pixel's color being off in one frame, or the tiniest little "tick" of static in the audio. Worst case, a movie file gets corrupted, and the usual solution is "just download it again". For archival or first-source storage this obviously doesn't work. I frequently work with multi-GB datasets, and since they're generated here, I can't "just download it again". And in that world, every bit actually matters. Similarly, in some other networks that I manage, one is a retail store chain (sales data, inventory data) and another is an office full of accountants (tax data), every bit matters. The solution here is mirroring and checksumming filesystems (i.e., ZFS) and limiting spindle sizes (and thus error rates). I myself will not go past 1TB for 2.5" drives or 3TB for 5.25" drives. I store all of my data in ZFS arrays with at least ten spindles in each. If I need more storage, I add more drives. Eventually drives in that capacity range will become unavailable, but I'll cross that bridge when I come to it. All I'm saying here is be careful, actually READ the specifications, and understand the markets that those drives are built for. The number of people out there who are watching movies and playing games dwarfs the number who are working to archive important data. This says a lot about our society in general, which makes me want to vomit, but that's beside the point and that reality is reflected in the products which are offered to all of us. -Dave -- Dave McGuire, AK4HZ New Kensington, PA