The short answer is: probably not.
But that answer doesn’t relate to the error message you’re seeing.
First, let me say: “Good on you for backing up!” Unfortunately, you’re still in the minority as we try to get more and more people to back up.
As I said, the short answer to your question is typically “no.” If your computer is sleeping, you cannot be guaranteed that the backup program will cause the system to wake up.
And waking up is exactly what it needs to do for the backup to process. Your machine must be running for a backup to happen.
Some backup programs include an option that claims to wake your computer in order to run the backup.
There are several problems, however:
- Not all backup programs have this option.
- The option may wake from Sleep, but not from Hibernate. If your machine is in Hibernate because it was in Sleep for too long, your backup will likely not run.
- If your machine is on battery — the most common scenario when using Sleep and/or Hibernate — the battery may run out before any backup has completed.
The only reliable option is to run the backup the next time the machine is powered on if a scheduled backup was missed. Once again, not all backup programs include such an option.
I/O device error
The error you’re seeing may or may not be related to attempting to run the backup immediately after waking up.
In my opinion, it’s more likely the error is an unrelated error accessing the drive.
Try a manual backup to see if that’s the case. If it works, my guess is that the scenario is playing out like this:
- Your external hard drive has stopped spinning to save power – either because the system went to sleep, or the drive itself spins down after some period of inactivity.
- The backup program starts and begins to access the external hard drive.
- The drive “wakes up” and begins spinning.
- The drive takes too long to be ready, and the computer or backup program declares the error.
When the backup program tries to access that external hard drive, it’s just not ready.
Solution 1: leave your computer running
I don’t know of a good solution in these situations, other than leaving your computer on.
That’s what I do. My computers run 24 hours a day, in part so scheduled activities such as backups can run in the middle of the night, when I’m not using the system.
Solution 2: run missed backups on login
As I mentioned earlier, in some backup programs there are options to automatically run any missed backup the next time you power on or log in to the machine.
The downside is, depending on the backup software you’re running, your machine may seem more sluggish while the backup proceeds.
But the benefit is that you’ll have a backup.
Solution 3: choose a different time
You can avoid the problem completely by choosing a backup time you know your computer will be up and running — perhaps during a daily lunch break or other time when the impact of a running backup won’t be as noticeable.