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Can you further explain why raid/replication isn't a backup? Sure, you can't backup beyond what you've replicated (locally or across a network), but for most f

Can you further explain why raid/replication isn't a backup? Sure, you can't backup beyond what you've replicated (locally or across a network), but for most folks, that should be fine.

bifrost 13y ago
You're kidding right? RAID is only good for dealing with HW failures, there are many more kinds of SW failure that can screw you and leave you with nothing, while having a perfectly good raid. Replication isn't a backup because if you screw up your dataset, well that screwup just got replicated.
joevandyk 13y ago
What happens if you accidentally run "delete from orders"? Or drop the database? Or need to access data that was updated in place last week?
redler 13y ago
Trolling, I assume? Just in case not: your own oh-shit moments (forgot that WHERE clause?), coding errors and oversights, bad luck, adversary SQL injection because the contractor who wrote some obscure admin page two years ago didn't know what he was doing, customer screw-ups (your web app customer fat-fingers their own critical data out of existence and begs you to roll them back to yesterday), etc. If you have a real business you need a multi-generational backup scheme of some kind.
sreitshamer 13y ago
"Backup" means, more specifically, multiple backups at various points in time.
bradleyland 13y ago
RAID and replication are good for protecting against hardware failure, but hardware failure actually accounts for only a handful of the reasons you want a backup. RAID, replication, and backups are all solutions to problems. Once you look at the problems instead of the solutions, your answer becomes clear. Often, the need for a backup arises from the need to go "back in time". RAID and replication offer no solution for this. Ok, so depending upon your replication setup, it may offer some help, but the steps required to go back in time usually involve starting from a recent backup, and using files involved in the replication to "replay" recent changes to get you back to the moment in the past you wish to return to.

Can you further explain why raid/replication isn't a backup? Sure, you can't backup beyond what you've replicated (locally or across a network), but for most folks, that should be fine.

bifrost 13y ago

You're kidding right? RAID is only good for dealing with HW failures, there are many more kinds of SW failure that can screw you and leave you with nothing, while having a perfectly good raid. Replication isn't a backup because if you screw up your dataset, well that screwup just got replicated.

joevandyk 13y ago

What happens if you accidentally run "delete from orders"? Or drop the database? Or need to access data that was updated in place last week?

redler 13y ago

Trolling, I assume? Just in case not: your own oh-shit moments (forgot that WHERE clause?), coding errors and oversights, bad luck, adversary SQL injection because the contractor who wrote some obscure admin page two years ago didn't know what he was doing, customer screw-ups (your web app customer fat-fingers their own critical data out of existence and begs you to roll them back to yesterday), etc. If you have a real business you need a multi-generational backup scheme of some kind.

sreitshamer 13y ago

"Backup" means, more specifically, multiple backups at various points in time.

bradleyland 13y ago

RAID and replication are good for protecting against hardware failure, but hardware failure actually accounts for only a handful of the reasons you want a backup. RAID, replication, and backups are all solutions to problems. Once you look at the problems instead of the solutions, your answer becomes clear. Often, the need for a backup arises from the need to go "back in time". RAID and replication offer no solution for this. Ok, so depending upon your replication setup, it may offer some help, but the steps required to go back in time usually involve starting from a recent backup, and using files involved in the replication to "replay" recent changes to get you back to the moment in the past you wish to return to.