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#30947 - 08/25/14 05:59 AM Time Machine Recognize An External Startup Drive?
Ira L Offline


Registered: 08/13/09
Loc: California
Disk Utility on an older iMac gave a S.M.A.R.T. warning on the internal hard drive. This machine has a Time Machine backup. My preference is to do a file level clone to a new external hard drive of the internal HD before it fails, rather than replace the internal drive. I would then use this new external drive as the startup all the time.

My question is does Time Machine do its back up of the startup drive, regardless of what it may be, or does it only back up the internal drive?
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#30951 - 08/25/14 03:21 PM Re: Time Machine Recognize An External Startup Drive? [Re: Ira L]
tacit Offline


Registered: 08/03/09
Loc: Portland, Oregon, USA
Time Machine will back up an external drive if you boot from it.
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#30952 - 08/26/14 04:29 AM Re: Time Machine Recognize An External Startup Drive? [Re: tacit]
Ira L Offline


Registered: 08/13/09
Loc: California
Yes, the plan is to boot from it.

Thanks.
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On a Mac since 1984.
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#31002 - 08/28/14 09:28 AM Re: Time Machine Recognize An External Startup Drive? [Re: Ira L]
Ira L Offline


Registered: 08/13/09
Loc: California
Just wanted to post an update in case some future reader encounters a similar problem. Bottom line: all is well.

I did need to go to Plan C or D to make it happen, though.

For some reason, while the drive was cloned successfully (Plan A) and showed up during a Restart-Option (to choose the external drive as the startup), the rotating gear would never stop. Argh. Sure it's a slower external USB drive, but bootable. Did not happen.

Plan B: boot into the Recovery partition of 10.8.x and reinstall from the Time Machine backup onto the external drive. The process started and got to 12% complete when a "Can't Continue, Restart" error message popped up. Arghh. So something on the Time Machine backup is corrupt (it does include System files)? Disk Utility verification said the structure, etc. are all OK.

Plan C: so maybe the Time Machine backup, which does include a System, backed up something from the original HD that was physically corrupted by the failing internal disk. So, boot into the Recovery partition and do a fresh install of 10.8.x. This happens as an Internet connection download and took hours, but was successful. Now OS X thinks the drive is a "new computer" and offered to set it up in a variety of different ways. I chose Migration Assistant (not Time Machine), which would bring over only user files, applications and settings. Success!! Running off of the external hard drive.

Did some App Store updates, one of which required a restart. Did the Restart-Option thing and external drive did NOT appear. Arghhh.

Plan D: The restart finished off of the old internal HD, went into Preferences>Startup Disk and the external was listed. Chose it, restarted and all is well again.

I'm not sure why the external USB drive appears in one startup place and not another, but it might be the USB ports? The external is directly connected, not through a hub, so any observations would be appreciated.
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On a Mac since 1984.
Currently: 27" iMacs, Macbook Air, macOS 10.14.x,; iPhones, iPods and iPads galore!

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#31003 - 08/28/14 10:38 AM Re: Time Machine Recognize An External Startup Drive? [Re: Ira L]
dkmarsh Offline

Moderator

Registered: 08/04/09

Did you try zapping the PRAM?
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#31006 - 08/28/14 02:01 PM Re: Time Machine Recognize An External Startup Drive? [Re: dkmarsh]
ganbustein Offline


Registered: 08/04/09
If you do zap the PRAM, don't forget to go back to System Preferences→Startup Disk and reselect your desired boot volume. Otherwise, the system will revert to booting from the internal (if it's still bootable), or boot slowly while it's waiting to see what drives will eventually spin up if it waits long enough, so it can choose one to boot from.

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#31012 - 08/29/14 09:05 AM Re: Time Machine Recognize An External Startup Drive? [Re: ganbustein]
Ira L Offline


Registered: 08/13/09
Loc: California
Good advice. Thanks, folks. smirk

And maybe it's a spin up problem on the external drive. It is USB/5400 rpm, not the faster 7200. Hmm…


Edited by Ira L (08/29/14 09:07 AM)
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On a Mac since 1984.
Currently: 27" iMacs, Macbook Air, macOS 10.14.x,; iPhones, iPods and iPads galore!

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#31022 - 08/29/14 03:32 PM Re: Time Machine Recognize An External Startup Drive? [Re: Ira L]
joemikeb Offline

Moderator

Registered: 08/04/09
Loc: Fort Worth, Texas
Ira, I don't want to hijack your thread, but I am having a similar, possibly related problem, but no solution. It sounds enough like your problem that I thought I would share it in hopes it might shed some additional light.

I have a copy of the Yosemite public beta installed in a partition on an external USB3 drive, there is a bootable copy of Mavericks on the other partition. Previously I could change the boot volume in System Preferences or do an "Option Boot" until I created the second partition on the drive and installed Yosemite on it. Since then, no matter what I do the only way to boot from either partition on the external drive is to use the Option boot from a COLD start. Even when the boot partition is nominally Yosemite even a restart from within Yosemite ends up booting from Mavericks on the internal disk. I have reported this to Apple as a Yosemite beta issue, but from your report it sounds as if it might be a prior issue.

Originally Posted By: Postscript
as an aside other than the boot issue the Yosemite beta is working well and the only failure I have encountered so far is the drivers for a Dymo Label printer and Dymo reports they are working on that. The new iCloud features are interesting, and according to Apple what you place on iCloud will remain there, but access to is a sometimes thing as they are still working on the iCloud software.


Edited by joemikeb (08/29/14 03:35 PM)
Edit Reason: add notice of report to Apple
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#31028 - 08/30/14 07:48 AM Re: Time Machine Recognize An External Startup Drive? [Re: joemikeb]
Ira L Offline


Registered: 08/13/09
Loc: California
Originally Posted By: joemikeb
Previously I could change the boot volume in System Preferences or do an "Option Boot" until I created the second partition on the drive and installed Yosemite on it. Since then, no matter what I do the only way to boot from either partition on the external drive is to use the Option boot from a COLD start.


Your comments and observations are always welcome. It is somewhat reassuring to hear that it might be a bug.

When you say "COLD start", do you mean from a shutdown as opposed to a restart?
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On a Mac since 1984.
Currently: 27" iMacs, Macbook Air, macOS 10.14.x,; iPhones, iPods and iPads galore!

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#31030 - 08/30/14 07:52 AM Re: Time Machine Recognize An External Startup Drive? [Re: Ira L]
joemikeb Offline

Moderator

Registered: 08/04/09
Loc: Fort Worth, Texas
Originally Posted By: Ira L
When you say "COLD start", do you mean from a shutdown as opposed to a restart?

Yes. It only works from a complete shutdown.
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#31037 - 08/30/14 05:06 PM Re: Time Machine Recognize An External Startup Drive? [Re: joemikeb]
ganbustein Offline


Registered: 08/04/09
System Preferences→Startup Disk saves your preferred boot volume in the computer's PRAM (aka NVRAM).

If it's not remembering your setting, either the PRAM is bad (possibly a weak battery?) or the external drive is taking so long to spin up that the boot code is giving up and settling for the next best option.

If the volume remembered in PRAM does not become available in a reasonable time, or there is no PRAM preference, it takes the first bootable partition on the first drive. (First by device number, not necessarily the first to spin up. Generally, that means the internal drive.)

From a cold start, the internal drive also has to spin up, and that may be slowing down the process long enough for the external to be seen in time.

Try resetting whichever of PRAM, NVRAM, or SMC is relevant to your machine, then once again select the boot volume in System Preferences→Startup Disk. If your machine has a PRAM/NVRAM battery, check it.

Note that option-boot does not alter the PRAM setting. It's used to temporarily override PRAM without affecting subsequent boots.

To learn which volume is currently selected as the boot volume, run the command:

bless --info --getboot

The output will be something like /dev/disk0s4. To turn that into a meaningful name, feed it into diskutil, as in:

diskutil info $(bless --info --getboot)

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#31038 - 08/30/14 09:04 PM Re: Time Machine Recognize An External Startup Drive? [Re: ganbustein]
MacManiac Offline
Moderator

Registered: 08/04/09
Loc: Paradise....on the central Ore...
Even when at root level I am unable to use the terminal command "bless --info --getboot" as suggested......

The resulting output is as follows:

sh-3.2# bless --info --getboot
Can't access "efi-boot-device" NVRAM variable

This is under OS X 10.9.4 on a late 2013 MBP Retina 13" with a 256GB SSD.......


Edited by MacManiac (08/30/14 09:06 PM)
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#31039 - 08/30/14 09:14 PM Re: Time Machine Recognize An External Startup Drive? [Re: MacManiac]
artie505 Online


Registered: 08/04/09
April 2010 15" MacBook Pro/2.66GHz/Core i7/8GB RAM/OS X 10.6.8 (Build 10K549), and the command runs as expected:

Code:
Artie's-MacBook-Pro:~ artie$ bless --info --getboot
/dev/disk0s2
Artie's-MacBook-Pro:~ artie$ 
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#31040 - 08/30/14 10:49 PM Re: Time Machine Recognize An External Startup Drive? [Re: MacManiac]
dkmarsh Offline

Moderator

Registered: 08/04/09

I get

$ bless --info --getboot
Boot option does not match XML representation
XML representation doesn't match true boot preference


on a late 2012 mini running 10.9.2.

Interestingly, going into System Preferences -> Startup Disk, no volume appears to be selected. Choosing the internal drive, exiting the prefpane, and running the command again gives the expected result:

$ bless --info --getboot
/dev/disk0s2
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#31042 - 08/31/14 01:20 AM Re: Time Machine Recognize An External Startup Drive? [Re: MacManiac]
ryck Offline


Registered: 08/04/09
Loc: Okanagan Valley
I get essentially the same as Artie….

my-names-imac:~ myname$ bless --info --getboot
/dev/disk1s2
my-names-imac:~ myname$

OS 10.8.5 iMac 20-inch Early 2008


Edited by ryck (08/31/14 01:21 AM)
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iMac (Retina 5K, 27", 2017), 3.4 GHz Intel Core i5, 8GB RAM, 2400 MHz DDR4
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#31044 - 08/31/14 01:07 PM Re: Time Machine Recognize An External Startup Drive? [Re: ganbustein]
MacManiac Offline
Moderator

Registered: 08/04/09
Loc: Paradise....on the central Ore...
So, taking a clue from other posts, I went into the Startup Disk PrefPane and selected my internal drive then quit System Preferences and ran the Terminal command successfully.....

My Acc't$ bless --info --getboot
/dev/disk0s2

Perhaps having recently reset PRAM for another issue may have contributed to my earlier failure.....and until I ACTUALLY selected a startup disk in the PrefPane, there was nothing for the Terminal command to recover.
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#31049 - 09/01/14 08:26 AM Re: Time Machine Recognize An External Startup Drive? [Re: ganbustein]
Ira L Offline


Registered: 08/13/09
Loc: California
Originally Posted By: ganbustein
or the external drive is taking so long to spin up that the boot code is giving up and settling for the next best option.


I suspect that may be the situation. It is an external USB 3, but the port is USB 2, at 5400 rpm. Small and quiet, though.

Fortunately there should not be too much need to restart, and if the internal drive eventually dies (recall the SMART alert), then the external will be the only choice.
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Moderator:  alternaut, dkmarsh, joemikeb