5 ms·

The 3-2-1 rule is a rule for a reason. 3 copies 2 formats 1 copy off-site The cloud is a great place for that 1 off-site copy.

jacquesm 11y ago
Assuming the rest of your data isn't in the cloud, yes. Otherwise reverse the situation. But you got it perfectly.
phinullfermata 11y ago
Modern 3-2-1: 3 backup services 2 formats 1 local copy I guess that could get expensive depending on the services.
- jacquesm 11y ago
  Yes, it could be. The trade-off is usually measured by the cost to the company of re-creating or losing the data entirely. So for some stuff such a system is feasible, for others it isn't and then you'll have to compromise. Log data for instance does not need to be stored like that unless there are legal rules saying that you have to keep it no matter what. For each business this is a delicate affair and you should spend some time on figuring out what you really absolutely have to have and what you could lose without losing the company or getting in trouble with the law.
ajross 11y ago
No argument at all about the last sentence, but you should have skipped the first four lines as wildly premature optimization. The vast majority of the world would be much better served by (to appropriate your jargon) a 2-1-1 rule, because it's a straightforward treatment for a straightforward problem that is easily implemented. Yes, "format skew" and double-failure of backup solutions does indeed happen, but at a much lower incidence than "oh crap I deleted it!".
- jacquesm 11y ago
  I think the 'three copies' rule refers to cyclic backups, not necessarily three copies of the one piece of data. This protects against data corruption that is not detected immediately. Another common way of doing this (and one that I prefer) is one where you rotate out a backup medium with ever larger intervals. So one gets set aside per week, then one gets set aside per month and so on. That gives you a series of snapshots in time that will allow you to pinpoint with some accuracy when an event happened. Longer ago you'll have less accuracy but this can help a lot in trying to triangulate who or what messed up. Just being able to answer the question of whether or not 'x' happened before 'y' was hired or after can help in narrowing down the number of suspects in case of a breach or other nastiness. It also prevents against back-ups for whatever reason not wanting to be reloaded (and you should guard against that by loading your back-up immediately after you make it, even so, the medium might fail the next time you try a read). Better still if there is a streaming log of everything but only very few companies can afford that sort of solution for all their data. Those can be hard to restore from (by replaying) so there too a snapshot system can help.
  - ajross 11y ago
    Oh sure, there's lots to say about the design and effective use of a backup regime. I agree with all that stuff. But if you're going to condense it to a "rule" that will help people not well-versed in the field, that rule can only be "MAKE BACKUPS!", because at least 90% of the data loss scenarios in the real world happen because simple backups weren't made. Don't make it more complicated than it is, because someone will stop to do it "right" and then lose data because they didn't just make a copy on a USB stick.

jacquesm 11y ago

Assuming the rest of your data isn't in the cloud, yes. Otherwise reverse the situation. But you got it perfectly.

phinullfermata 11y ago

Modern 3-2-1: 3 backup services 2 formats 1 local copy I guess that could get expensive depending on the services.

jacquesm 11y ago
Yes, it could be. The trade-off is usually measured by the cost to the company of re-creating or losing the data entirely. So for some stuff such a system is feasible, for others it isn't and then you'll have to compromise. Log data for instance does not need to be stored like that unless there are legal rules saying that you have to keep it no matter what. For each business this is a delicate affair and you should spend some time on figuring out what you really absolutely have to have and what you could lose without losing the company or getting in trouble with the law.

ajross 11y ago

No argument at all about the last sentence, but you should have skipped the first four lines as wildly premature optimization. The vast majority of the world would be much better served by (to appropriate your jargon) a 2-1-1 rule, because it's a straightforward treatment for a straightforward problem that is easily implemented. Yes, "format skew" and double-failure of backup solutions does indeed happen, but at a much lower incidence than "oh crap I deleted it!".

jacquesm 11y ago
I think the 'three copies' rule refers to cyclic backups, not necessarily three copies of the one piece of data. This protects against data corruption that is not detected immediately. Another common way of doing this (and one that I prefer) is one where you rotate out a backup medium with ever larger intervals. So one gets set aside per week, then one gets set aside per month and so on. That gives you a series of snapshots in time that will allow you to pinpoint with some accuracy when an event happened. Longer ago you'll have less accuracy but this can help a lot in trying to triangulate who or what messed up. Just being able to answer the question of whether or not 'x' happened before 'y' was hired or after can help in narrowing down the number of suspects in case of a breach or other nastiness. It also prevents against back-ups for whatever reason not wanting to be reloaded (and you should guard against that by loading your back-up immediately after you make it, even so, the medium might fail the next time you try a read). Better still if there is a streaming log of everything but only very few companies can afford that sort of solution for all their data. Those can be hard to restore from (by replaying) so there too a snapshot system can help.
- ajross 11y ago
  Oh sure, there's lots to say about the design and effective use of a backup regime. I agree with all that stuff. But if you're going to condense it to a "rule" that will help people not well-versed in the field, that rule can only be "MAKE BACKUPS!", because at least 90% of the data loss scenarios in the real world happen because simple backups weren't made. Don't make it more complicated than it is, because someone will stop to do it "right" and then lose data because they didn't just make a copy on a USB stick.