Putting hard disks to sleep via script?

[haravikk]

Hmm, because of a RAID card I've added (RocketRAID 4310) it seems I have to disabled the "Put hard disk(s) to sleep whenever possible" feature in Energy Saver, as if the card's volume is ever put to sleep, it never wakes and the whole system crashes down, well, if the volume is the startup disk anyway, which it is in my case.

However, I also have three external drives, and it'd be nice if these would still go to sleep, but the feature appears to be a system-wide thing, either all drives have sleep enabled, or none do.

I'm wondering if there are any other options for this? For example, my largest external drive is a time-machine backup, so it'd be nice if it only spun-up when the backup begins, then spins down afterwards, any way to do this?

 

[haravikk]

Wanted to bump this as I've still not been able to find any good solution.

What I'd like to know is if it is possible to reliably detect when Time Machine is about to begin a back-up, and when it has finished? The reason I ask is still that my back-up drives are really annoying me, as for some insane reason OS X seems to think that it needs them to be mounted in order to perform some file-system operations, even though there is nothing on them except my time machine back-up(s).

It gets especially annoying as it can hugely delay file open or save dialogues, and also randomly slows programs like Safari when they're forced to wait while the drives spin up, just because its accessed the cache or something, even though my back-up drives have nothing to do with that process.


So I'd love to be able to unmount my time-machine volume when not in use, to force the drives to spin-down and stay that way until Time Machine needs them again.

Is there any way to detect the moment when Time Machine begins in such a way that I can mount the drives in time to be ready, and likewise unmount them when it's done? Preferably with the ability to do the same for when I choose the "Enter Timemachine" option, though manually mounting the drives in this case isn't such a big deal.