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Level 1

56 points

External disk - repair permissions

It seems the permissions on my HD need to be repaired.

Unfortunately I have lost the Repair disk during an international move.

I still have the install disk - so I tried to install OS 10.6 onto an external drive. The intention was to boot from the external drive and repair permisions on the MacBook HD.

The installation kept showing the external disk as having not been ejected correctly, which is not correct. Anyway, I erased all partitions on this external disk, using Disk Utility, did a 7 pass erase, and then also ran the repair disk function too; Disk Utilityshowed that there were no issues with this external disk. However, I still got the same result from the OS installation program, that the external disk had not been ejected correctly. I went around in the circle a number of times before giving up.

Now I am at a loss how to make the external boot disk to repair permisions on the computer HD.

I know in the distant past it was possible to just copy the System folder to an external drive and it would boot; but I was told this no longer works.

Any get around this issue or a solution would be most welcome.

Thank you

Posted on Apr 3, 2012 2:03 PM

27 replies

Memoire Author

Level 1

56 points

Apr 4, 2012 5:50 AM in response to WZZZ

Hi WZZZ thank you for your kind reply, now I remembered the point you made about Repairing Permissions with the same OS as on the internal boot drive; whoops. But the current stability is luckily much better than before I ran Disk Repair and Repair Permisions; well at least for now :-)

This requirement to use the same OS to repair Permissions was initially why I was trying to make a bootable external drive using the install disk, then update it and run DIsk repair. But the direction changed with the various posts. However the external drive after formating, checking integrety still showed when I tried to install OS 10.6 that "the external disk had not been ejected correctly".

You're right that repairing permissions was an original requirement in past OS's, but old habits die hard:-)

So basicially I am back to the original issue of how to get OS10.6 installed onto my external drive.

As always thank you for your kind reply.

fane_j

Level 4

3,697 points

Apr 4, 2012 6:10 AM in response to Memoire

Memoire wrote:

I can't understand what point you are trying to make

Very well, I'll try to explain again.

(1) Repair Disk and Repair Disk Permissions are two fundamentally different tasks. What Repair Disk Permissions does is explained in Apple KB docs HT2963 and HT1452, linked to above.

(2) While Repair Disk can, and sometimes should, be performed from a different boot volume, Repair Disk Permissions should be done so only if there is no alternative. If one can boot from the respective hard disk, one should run the Repair Disk Permissions from it. The reason is, as I told you before, explained in HT1452.

Making this any clearer is well beyond my poor abilities.

Suid File corruption was show within Repair Disk

No. SUID is not corruption and it is not (it cannot) be "show within Repair Disk", because the underlying task does not check for setuid or any other file permissions.

Apr 4, 2012 6:32 AM in response to WZZZ

You don't want to repair Permissions booted from the install DVD. This will give you the Permissions for the version on the DVD.

Let's dispel another myth. The Install DVD (10.6) does not contain any receipts. So, the receipts read are those on a valid boot volume. In 10.2 the utility used a special file called hintList.plist (located within the Disk Utility application) that modified the permission settings in the hard coded Archive.bom files. So, in that version, you should use the utility on the boot volume. The file was moved into the System folder in 10.3 and if I remember correctly, using the the boot volume or the CD version of Disk Utility made no difference.

Memoire Author

Level 1

56 points

Apr 4, 2012 6:52 AM in response to fane_j

fane_j wrote:

Memoire wrote:

I can't understand what point you are trying to make

Very well, I'll try to explain again.

(1) Repair Disk and Repair Disk Permissions are two fundamentally different tasks. What Repair Disk Permissions does is explained in Apple KB docs HT2963 and HT1452, linked to above.

(2) While Repair Disk can, and sometimes should, be performed from a different boot volume, Repair Disk Permissions should be done so only if there is no alternative. If one can boot from the respective hard disk, one should run the Repair Disk Permissions from it. The reason is, as I told you before, explained in HT1452.

Making this any clearer is well beyond my poor abilities.

Suid File corruption was show within Repair Disk

No. SUID is not corruption and it is not (it cannot) be "show within Repair Disk", because the underlying task does not check for setuid or any other file permissions.

The situation is now resolved. As I stated: 'I can't understand what point you are making. Of course Repair Disk and Repair Disk Permissions are two fundamentally different tasks. The Disk Repair was necessary and the Repare Permissions resolved a number of issues that were show in the status window. Thanks to WZZZ I reran the Repair Permissions from the internal boot drive and it resolved also issues shown in the status window.

The Suid file was shown as corrupted after running Repair Disk in the Disk Repair status window, with the comment that Disk Repair couldn't repare this fine; this is a fact; the issue is not to argue like a Kindergarden playground.

Memoire Author

Level 1

56 points

Apr 4, 2012 6:58 AM in response to WZZZ

WZZZ wrote:

The exact solution!

Not really. You don't want to repair Permissions booted from the install DVD. This will give you the Permissions for the version on the DVD. Since you are running 10.6.8, not 10.6.2 or.3, the disc version, repairing from the DVD will actually introduce errors, which will then have to be repaired while booted normally. You should always repair Permissions booted normally.

Permissions repair in earlier versions of OS X, perhaps even as recent as Tiger (and doubtful even there) may once have been a useful general troubleshooting step, but no longer. I have never seen my Permissions altered one wit since I've been running Snow Leopard (and Leopard.)

Some suggested reading on the myth of Permissions repair.

http://unsanity.org/archives/000410.php

Thank you WZZZ, I re-ran Repare Disk Permissions from the internal boot drive and it repaired quite a number of permissions; I appreciate the tip. As always your help is perfect.

WZZZ

Level 6

13,226 points

Apr 4, 2012 7:09 AM in response to Mark Jalbert

Mark Jalbert wrote:

You don't want to repair Permissions booted from the install DVD. This will give you the Permissions for the version on the DVD.

Let's dispel another myth. The Install DVD (10.6) does not contain any receipts. So, the receipts read are those on a valid boot volume. In 10.2 the utility used a special file called hintList.plist (located within the Disk Utility application) that modified the permission settings in the hard coded Archive.bom files. So, in that version, you should use the utility on the boot volume. The file was moved into the System folder in 10.3 and if I remember correctly, using the the boot volume or the CD version of Disk Utility made no difference.

So some real world experience: then please explain why it was that, on the occasion some years ago of being given bad advice, when I repaired Permissions in 10.4 booted from the install CD, Permissions repair, subsequently booted normally, found numerous genuine errors that then needed to be repaired.

jsd2

Level 5

6,245 points

Apr 4, 2012 7:14 AM in response to WZZZ

My understanding is that for the items that do leave receipts in that folder, it doesn't matter where Disk Utility is run from - Disk Utility does always look at the list on the target volume.

I'm not sure this is correct, but my understanding is that for some basic system files, the "desired" permissions are not kept in the Receipts folder (they were never installed by an installer) but are rather stored within Disk Utility.app itself. If the "desired" permissions for those files are later changed by an OS X software update, then you would need a new version of Disk Utility.app to allow for this, and that is the reasoning behind this entry in the support article:

-----------------

Should I start up from a Mac OS X install disc to repair disk permissions?

When possible, disk permissions should be repaired while started up from a Mac OS X volume (hard disk) that contains Mac OS X, instead of a Mac OS X installation disc. Mac OS X software updates may change permissions on some files to improve security. When this occurs, the version of Disk Utility on the Mac OS X volume is updated to account for the new permissions. Running Disk Utility while started from the Mac OS X volume ensures that the changes made by software updates are preserved.

---------------------

It's not the Receipts list that needs updating (the only list is on the HD), it is Disk Utility.app itself. If you peek into the SL 10.6.8 Combo Updater, it does contain an update for Disk Utility.app

Memoire Author

Level 1

56 points

Apr 4, 2012 7:17 AM in response to WZZZ

WZZZ wrote:

Mark Jalbert wrote:

You don't want to repair Permissions booted from the install DVD. This will give you the Permissions for the version on the DVD.

Let's dispel another myth. The Install DVD (10.6) does not contain any receipts. So, the receipts read are those on a valid boot volume. In 10.2 the utility used a special file called hintList.plist (located within the Disk Utility application) that modified the permission settings in the hard coded Archive.bom files. So, in that version, you should use the utility on the boot volume. The file was moved into the System folder in 10.3 and if I remember correctly, using the the boot volume or the CD version of Disk Utility made no difference.

So some real world experience: then please explain why it was that, on the occasion some years ago of being given bad advice, when I repaired Permissions in 10.4 booted from the install CD, Permissions repair, subsequently booted normally, found numerous genuine errors that then needed to be repaired.

Exactly what I found WZZZ, when I ran Repair Disk Permissions from the internal drive as you recommended I did get a whole list of files that needed repair by Repair Disk Permisions which were then subsequently repaired.

WZZZ

Level 6

13,226 points

Apr 4, 2012 7:22 AM in response to jsd2

jsd2 wrote: It's not the Receipts list that needs updating (the only list is on the HD), it is Disk Utility.app itself. If you peek into the SL 10.6.8 Combo Updater, it does contain an update for Disk Utility.app

As always, the formidable jsd2 comes in and nails it on the head. Thanks.

jsd2

Level 5

6,245 points

Apr 4, 2012 7:40 AM in response to Memoire

I did get a whole list of files that needed repair by Repair Disk Permisions which were then subsequently repaired.

Are you sure they were "repaired"? Here is an exercise for you: run Repair Disk Permissions again, both from the HD, and if you like, from the Install DVD. Repeat as many times as you like.

What do you see?

As mentioned earlier, take a look at

Mac OS X: Disk Utility's Repair Disk Permissions messages that you can safely ignore

fane_j

Level 4

3,697 points

Apr 4, 2012 7:54 AM in response to Memoire

Memoire wrote:

the issue is not to argue like a Kindergarden playground.

Could you please direct me to the 'Kindergarden' playground where they make references to Apple KB docs? I'd like to send my daughter there.

On second thoughts, forget it. I give up.

fane_j

Level 4

3,697 points

Apr 4, 2012 7:58 AM in response to jsd2

jsd2 wrote:

my understanding is that for some basic system files, the "desired" permissions are not kept in the Receipts folder (they were never installed by an installer) but are rather stored within Disk Utility.app itself. If the "desired" permissions for those files are later changed by an OS X software update, then you would need a new version of Disk Utility.app to allow for this, and that is the reasoning behind this entry in the support article:

That's also my understanding. That's why I pointed the OP to that very section of HT1452. But, as they say, one can lead a horse to water…

External disk - repair permissions