Many people do not seem to understand about backup and its role in the original poster's dilemma.
These data are photos and videos that are irreplaceable. Several horror stories have been posted about going back to online disk data years later and finding it unreadable.
So the short answer is ALL rotating storage fails, period. Yes even ups backed up raid-N; Pick any N you like. If the data are the irreplaceable photos of your children then think: hurricane; flood; fire; lighting; nasty power failure; power brownout; virus; accidental corruption or destruction; memory failure; etc...
The rule is: If the machine, the power company and the Net can see it can be hurt!
Therefore the First Step in protecting data is get it copied, get it OFF-Line and then get it away from site.
Getting it copied is the point of this thread and the OP is right:
- DVD is not there yet though Sony's Blu-Ray looks promising. The Blu-Ray disc is encased to protect it from scratches and UV damage.
- Removable disk at first blush looks good but they are very susceptible to physical damage. Ask yourself this if your backup disk fell out of your hand and hit the floor what would be your first thoughts? To test it to see if it had survived. Obviously not a good offsite backup candidate.
- And then there's Tape. Which is the only ...
Well for the time being yes. It is still the least expensive $/GB. Which makes it a little less painful to follow the Cardinal Rule of Backup:
Backup often and Test/Read/Verify every backup. That way you have snapshots of your data at various points in time. (This can be very important when data is being slowly corrupted by flakey hardware or malicious viruses).
As far as what to use for a home system, the Sony AIT1/2/3 units are some of the lowest cost and are the most reliable in the industry. (Real world data here; Period.)
For business LTO2/3 is the weapon of choice at the high end. Though Sony AIT3/4/S is an excellent choice in the mid to high price sensitive (SMB) market.
Try and avoid the temptation of going too cheap. After all we prefaced this thread on the fact that the data is priceless.
For example DAT drives are an industry joke. The manufacturers have gotten together several times trying to all agree to kill the damn thing. If it were not for its low cost to the system OEMs it would be long gone. Definitely not reliable/large/fast enough for backup! In fact DAT drives are the only drives worse in the field then the Exabyte drives.
And make sure to use a software package that uses a format that will be supported in the future. (think tar, dump, Amanda, windows backup, etc) As a rule of thumb no package with less than ten percent market share is likely to survive long term or be supported by their larger competitors.
The last part (of the First Step) is easy; your local Bank will rent you a safety deposit box. And really, you should have one anyway for the low tech irreplaceable items that you need to protect. Rent one and keep at least every other backup tape in the Bank.
The Second Step in protecting your data is keep a log of what is in the safety deposit box and what media/format it is in.
Why? A case in point. In recent years it has been virtually impossible to get certain Exabyte tape drives repaired. So much so that dealers were buying up all the used ones. Finally with no more availability, used ones were selling for more than new because new ones were in short supply as well (tape head problems) This happened repeatedly with more than one model of drive from them, over several years.
The point is if your backup data is on one of those Exabyte tapes and your tape drive fails, you cannot read your data. Nobody can fix it and you cannot get a replacement. So in reality you are just as bad off as you would be if you had NEVER BACKED UP. Exabyte is a good example here because they are slowly going out of business. When they do, in short order everyone who owns their drives is screwed when it fails. And ask anyone who knows; they always fail.
Anyway keeping the media/format log allows you to review and identify when an archive media needs to be copied over to a non-obsolete media. You should also periodically remove a random tape from the Safety Deposit Box and verify that it is still readable. After which return the tape to the Bank and note the date last verified for it in the log.
In keeping with the personal use theme, try and keep your backup procedures simple. The simple and easy plan is more likely to actually get executed. The biggest problem with backup is that people are not vigilant. They stop doing it and sooner or later they all lose data.
This is of course is a condensation of a very large and important problem. I hope it helps.
