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Level 2

231 points

GUID for backup?

Yet another partition/backup question. I've searched and read, but still need to ask...

I have a new iMac and want to do several HD backups for redundancy and safety. I have made my first backup on one HD which I am devoting just to the iMac.

I use SuperDuper and external LaCie d2Quadra drives. I'd like to have a backup bootable copy of the iMac and the MBP on each of 3 other drives. I know if the drive fails I loose the backups of both computers, but if I have copies of both computers on several different drives I should be OK.

From the directions on SD's site for preparing the drive and partitioning:

4. Use Disk Utility's controls to divide the drive as needed, even as a single large partition. Use "Mac OS Extended (Journaled)" as the format type and name appropriately

5. Click the Options button

6. Choose the proper partition scheme (GUID for Intel macs, Apple Partition Map for Power PC) and accept the page

7. Click Partition.

Partitioning in GUID seems to be the right choice.

Using GUID, and remembering that one of the last steps in a HD SmartUpdate on SD says something like, "make bootable," I assume that the drive will be bootable for both the iMac and the MBP.

With GUID, can a partition with photos stored on it be accessed by PPC iBook? Can photos & docs be accessed by the iBook if they are on the iMac partition?

Final question, earlier I made a backup of the MBP on yet a different drive - I'm pretty sure I used APM as the partition scheme. Does that mean that copy is not bootable?

Thanks for your help,

Mrs H

Posted on Aug 11, 2011 2:27 PM

Best reply

Kappy

Level 10

361,741 points

Posted on Aug 11, 2011 4:35 PM

All OS X drives should be partitioned using GUID and formatted Mac OS Extended, Journaled. You can store any files on such a drive regardless of their source.

Intel Macs cannot boot from an APM partitioned drive. You can make any number of partitions on a single drive. The GUID map applies to the entire drive regardless of how many partitions you then make on that drive.

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18 replies

Aug 13, 2011 2:24 PM in response to Mrs H

Yes, I'm surprised at the problem with the connections. Is it just Sandisks or do other drives have a similar problem?

As for U3, I've never noticed it! Mind you, my current crop of drives are all Lexar (I just checked).

Anyway, repartitioning and zeroing should get rid of it.

Mrs H Author

Level 2

231 points

Aug 14, 2011 8:52 AM in response to noondaywitch

noondaywitch wrote:

Yes, I'm surprised at the problem with the connections. Is it just Sandisks or do other drives have a similar problem?

As for U3, I've never noticed it! ...

Anyway, repartitioning and zeroing should get rid of it.

Sorry I didn't reply sooner. I just noticed your reply. I'm not happy with my profile page set-up; I seem to miss some updates.

Not just Sandisks - HP too. We (foolishly) tried using the extension cable provided with our USB keyboard. Apparently (who knew?) it's supposed to be used to make the keyboard have a longer reach to the back of the iMac. In reality we figured it could work as a port for a flash drive - USB2 is USB2 - unless the keyboard itself is not powerful enough to access the flash drive. We tried plugging an HD drive in and had a really hard time getting it disconnected. So, thinking we were smart, we tried connecting male to female on the extension cable - and now it's stuck together and can't be separated. At least that tells me the female cable end is too tight and it's probably not our flash drives' problem with connecting there. At the back of the iMac, though, same thing - it's such a tight fit that I don't dare push it in - it'll never come out. AppleCare on Monday...

As far as U3 - if you had you'd know. It's on the newish Sandisks (mine are a few years old I think). some sort of app that works with windows. Trouble is when the disk mounts it mounts twice once with an icon for the disk and once with a CD-looking icon for U3. When you eject the disk icon, you have to do a second eject of the U3. Sandisk provides software to remove U3 but, as I said somewhere, I've read really mixed reviews on how successful that is. I would think that if a simple, repartition, zero-out, reformat would get rid of it Sandisk would suggest that...

Mrs H

Aug 14, 2011 9:14 AM in response to Mrs H

U3 appears to be a seperate partition, so repartioning as 1 partition and GUID should clear the whole drive. If it doesn't, I wouldn't buy Sandisk again!

GUID for backup?