Why are my external HDs ejecting themselves?

[Reality4711]

Hello all,

I run a MacPro 3.2Octo on SL..

Two external HDs connected. firstly/ usb(original) is my Time machine and secondly/800FW (original) is my ITunes library.

When my machine goes to sleep - either itself or on demand - on awakening one or both HDs have ejected themselves and the error message is displayed.

Sometimes they re-connect but not always.

Is there some setup I have missed (energy setting - put HDs to sleep when possible is not ticked) or another glitch I am unaware of.

Apologies if this is old stuff. References to previous solutions would be just as helpful.

Thank you.

 

[Corrosive vinyl]

What happens when the Mac goes to sleep (not just into idle mode or display sleep)?

On all Macs:

The microprocessor goes into a low-power mode
Video output is turned off, and a connected display may turn off as well, or enter its own idle state
Apple-supplied hard disks spin down; third-party hard disks may spin down
On portable Macs:

The Ethernet port turns off, if applicable (see note below)
Expansion card slots turn off
The built-in modem, if present, turns off (see note below)
An AirPort card, if present, turns off (see note below)
The USB connection only responds to the power key on an external keyboard (see below)
The optical media drive spins down
Audio input and output turns off
Keyboard illumination, if a feature of your portable computer, turns off

Apple Support site

 

[Reality4711]

Thank you.

It is when the Mac fully goes to sleep that the ejection occurs.

The seeming randomness is the frustration. It does not seem to have any logic to it.

It was not a problem on my G5 or using Leopard on this machine.

I have read your references (scanned) but am unable to see this referenced - it all seems to be what should happen rather than what if it doesn't

Thank you again.