Booting Firewire external drive

[Csmac]

I'm running El Capitan Public Beta on an external drive and have run into a strange, to me, situation.

Booting to the external drive works fine unless I've powered off. In that case powering up and holding the Alt. key only comes up with the internal drive as available. When the OS on the internal drive, Yosemite, boots up it still doesn't see the external drive unless I unplug it and then plug it in again. At that point I can "restart" and hold the Alt key and then boot to the external drive. Is this how it is supposed to be? If the internal drive dies or isn't bootable will the hardware then see the external drive?

Cliff

 

[chscag]

No, that's not how it's supposed to work. I also have El Capitan loaded on an external drive and can boot to it by holding down the "Option" key and choosing it. The choice to boot to the external drive should come up whether or not the internal hard drive is present - (as long as you hold down the Option key). It sounds like there may be a problem with the external drive or USB cable.

 

[Csmac]

Thanks Chacag for the reply.

How you described it was what I expected. In considering my reply I remembered that the drive enclosure is powered by the Firewire port and the only time I power off is usually when I am traveling somewhere. In experimenting I found that it found the external drive here at home just fine even with a power off. I then unplugged the drive with it the MBP off and plugged it back in and it still found the drive. I then disconnected the charger and noticed that the light on the drive went out so after 30 seconds or so plugged in the charger and powered on and it found only the internal drive UNTIL I held the Option key longer then it found the external drive. Apparently it takes a little while to get powered up to the point that the boot ram can see it.

All that to say it works correctly after all, just the operator didn't understand how to do it. Thanks for getting me thinking.

Cliff

 

[chscag]

Glad you figured it out. Thanks for posting back.

 

[Csmac]

Another related question if I may - if my MBP is put to sleep (top closed) and the charger disconnected so the light on the external HD is out, is there any problem with disconnecting the external drive as long as I reconnect it before waking up the laptop? Thanks.

 

[chscag]

Yes, because when you remove (dismount) the external drive it may wake the MBP and cause corruption to the drive. Best not to do it.

 

[Csmac]

Thanks. I had a suspicion that that might be the case so haven't dared try it. Now for sure I won't. I can see that power off is the only safe way. I appreciate your input very much.

 

[harryb2448]

Are you quite sure when you formatted the external drive, went into Partition > Options and selected GUID? Failing to do that will prevent seeing the drive on Boot an Option. And as chscag rightly points out., FW800 is not hot swappable as USB is claimed to be.


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