Wrong: RAID1 on the backup drive makes a total of 3 drives. But it does cover near-zero data loss risks if faulty disk is replaced as soon as failed, doesn't it?
I was "wrong" to assume that you were using RAID1 for primary storage. You earlier asked, "...Using a RAID1 as a destination rather than a single drive?" If you'd said 'Using a RAID1 as a backup,' your meaning would have been more clear. Still, that begs the question of why you'd have a single drive as primary storage, backed-up by a RAID1? You've created a more reliable backup, but have done nothing for the reliability of primary storage. If the 'best backup' can be defined as, "The backup you never have to use," then primary RAID1, single-disk backup makes more sense (to me) as an allocation of three HDDs.
Fire & Flood = geographical separation, then? Your strategy doesn't seem to include full backups offsite, and that was also my main issue: not being able to have a full offsite backup.
I guess you mean my
personal backup strategy, which I already admitted does not qualify as industrial strength. I was quite clear that my definition of industrial strength
does include full off-site backup.
Cloud providers just don't have the necessary space, nor privacy.
Off-site these days implies 'cloud,' but it's not the only method by any means. When I was doing corporate IT back in the 90s, it meant sending a streaming tape of our RAID5 server to an offsite repository on a regular schedule. There are those who take a portable drive home with them at the end of the work day, others deposit those portable drives in bank vaults on a regular schedule (since theft is also a consideration, encryption of those backups seems a good idea).
Real-time off-site backup has advantages over a periodic snapshot of that sort, but even then, it can be a matter of using a VPN to send the data to another site under your control, rather than put it in the hands of strangers.
I uninstalled Dropbox when I learnt about hubiC, that now offers backups (automated or manual) and have very large spaces available for so few bucks. In which case the upload bandwidth becomes a limiting factor for the first backup. They also have a plugin available if your local backup happens to be a Synology enclosure.
I calculated that my strategy allows me to be running again in about 30 min for critical documents, overnight for full restore, with a maximum loss of about 12 hours of work. This was before SpiderOak's utter failure to repair my space, and before the single backup drive unexpectedly failed despite really low usage.
The problem is that cheap backup is affordable, but prices climb very quickly once you factor in options such as NAS, external providers, and other, distant NAS.
I'm not going to say "industrial strength" means "cost is no object," but an industrial enterprise probably does have more money at stake, so their cost-benefit analysis can allow for solutions that are prohibitively expensive for the single user/very small business.
In the end, it's not whether a backup is "industrial strength" by my casual definition or any other - it's whether the strategy selected is appropriate to a user's needs, based on a well-reasoned assessment of risk and cost.
If there's an ISO standard that includes backup strategies, that would be a better measure of "industrial strength" than anything we can debate here.