Twenty years ago the option available to me to back up my machine was reel-to-reel tape drives. I'd bring my machine down to single-user mode to perform the backup, and each tape would take 12 minutes.
I remember this because we would set the time on a portable kitchen timer when we started each tape. When the timer went off, we'd head to the computer room to swap out the tape, and go to the console to press G to continue the backup. The real fun came toward the end of the process. If the media that was being written to was bad, the backup job would abort, and you'd have to restart the backup from the beginning.
There were four boxes of tapes that would go offsite each week. I can't recall how many tapes fit in each box (10 maybe?) or the capacity of each tape. I do remember that a box of reel-to-reel tapes was relatively heavy. I can only wonder if my current collection of lightweight USB flash drives that floats around my computer bag contains more capacity than the system that I was backing up at the time.
Our users didn't work on nights or weekends, so there was a built-in maintenance window during the night and on the weekends so we could do the necessary work on the machine. Of course there wasn't any online access to accounts in those days, and we didn't have offices outside the U.S., so 24-7 availability wasn't necessary. Some might argue that things were easier with such large maintenance windows, but I can remember backups taking a long time, disk capacities being much smaller, job run times being much longer, etc.
The point of this trip down memory lane is to illustrate how good things are today. Processors have made huge leaps in the last 20 years. Disk capacity and performance gets better year over year. Backup windows have shrunk to nothing--in many cases applications have APIs built in that allow products such as Tivoli Storage Manager to backup data while the application is up and running. In other cases,
you can quickly quiesce an application, take a flash backup on your disk subsystem and then restart the application. In many instances the interruption is so brief your users don't even notice.
When we include products like HACMP and capabilities like Live Partition Mobility, our need for maintenance interruptions falls off dramatically. If you're still doing the equivalent of taking your
machine into single-user mode to perform backups, or if you're still manually performing many of these tasks, it may be time to re-evaluate your processes. Today, there's a better way of doing things.