External firewire drives randomly come on and slow down my imac

[Learjet035]

I've had this issue with both my previous MBP and now my imac 27".

My 2 external FW800 drives randomly come on and spool up and pretty much lock down my computer for a few seconds. Its just annoying, nothing really more than that.

Anyway to stop this? I'd leave them disconnected but I have random backups that happen on odd days and hours.

Thanks!!

 

[Makosuke]

Not much you can do--what's happening is you've done something that causes the OS to poll the available storage devices (a common one is bringing up an open/save dialogue, even if you haven't selected the disk in question), which causes the drives to spin up and the OS to wait until they've responded to continue.

Turning off "sleep drives when possible" will help, but some drives still spin down (in particular WD's Green series--a real issue since their default spin down time is set to 8 seconds). But of course that's also noisier and wastes electricity. Until Apple makes disk I/O fully asynchronous (may never happen, although it's been getting DRASTICALLY better with network access, so I have some hope), this is always going to be an issue.

Alternative: If your backup software is capable of automatically mounting/unmounting a volume (I could be wrong, but I think some are), have it mount before a backup and unmount after. If you keep your backup drive(s) attached to a server, and do backups over the network, this is much easier (that's what I do)--even Time Machine will mount-backup-unmount network volumes as needed, and since they're not normally mounted you never have spin-up issues.

 

[Learjet035]

Thanks for the explanation.
Glad its not something wrong.

How about a script that would mount and then eject my drives prior to my backups?
I tried the script recorder but with no luck. I'm not to skilled with using that thing anyway.

Any ideas on a way to do that?

Thanks again

 

[Makosuke]

Well, a Google search for "mac mount drive before backup" comes up with several hints from the always-useful MacOSXHints.com, in particular these:

Mount/Unmount external drive for backup

and

Mount firewire drive via shell script

Should at least get you started.