Preventing auto startup from backup volume

[dINGO]

This is probably something I misconfigured, but I cannot seem to fix it (I am a only a 7 mo convert to macs).

I do a full backup to a usb hd (seagate freeagent)

If I have the usb hd attached on starting the mac, the mac boots from the usb hd automatically. (Now, I used to have SD set to make the backup a start up disk, but I changed that to just shut down computer, but the problem continues).

The problem is if I don't realize this is happening and work on the mac, things are just getting saved on the usb hd which will be wiped on the next backup. This is very bad.

Any ideas why the usb hd is the default startup volume / disk, and how to change this.

TIA

[chris_johnsen]

Originally Posted by dINGO

If I have the usb hd attached on starting the mac, the mac boots from the usb hd automatically. (Now, I used to have SD set to make the backup a start up disk, but I changed that to just shut down computer, but the problem continues).

The problem is if I don't realize this is happening and work on the mac, things are just getting saved on the usb hd which will be wiped on the next backup. This is very bad.

I am pretty sure you can clear this up by changing the settings in the Startup Disk pane of the System Preferences application. If you go there, you should see your USB disk and your internal disk as options. Just select the internal disk (and then reboot, if you are running from the USB disk).

Here's my attempt at an explanation of your current situation: Turning off SD!'s option to change the startup volume to the new backup does not mean that SD! will reset the startup volume to some kind of default. It just means that SD! will leave the startup volume setting unchanged. In this case, it sounds like your computer is configured to boot from your USB disk. Based on what you wrote, SD made the initial change of startup disk from internal to USB, but SD! does not (cannot?) keep track of who changed the startup volume setting, so it cannot really know that you might want it to be changed back.

--
Chris