"The contents of this disk can't be changed."

Snow cannot be used to upgrade Tiger. You must either erase the disk and install from scratch or upgrade Tiger to Leopard, then upgrade Leopard to Snow.

The boxed set comes with Leopard and Snow. Upgrade to Leopard then upgrade to Snow. Or erase your drive and install Snow from scratch. Be sure to make a clone of your system before erasing the drive. You can clone as follows:

How to Clone Using Restore Option of Disk Utility

1. Open Disk Utility from the Utilities folder.
2. Select the destination volume from the left side list.
3. Click on the Erase tab in the DU main window. Set the format type to Mac OS Extended (journaled, if available) and click on the Erase button. This step can be skipped if the destination has already been freshly erased.
4. Click on the Restore tab in the DU main window.
5. Select the destination volume from the left side list and drag it to the Destination entry field.
6. Select the source volume from the left side list and drag it to the Source entry field.
7. Double-check you got it right, then click on the Restore button.

Destination means an external drive you will use.
Source means your current startup drive.

i have leopard and tried to upgrade to snow leopard last night
but receive the same error message that "the contents of this disk can't be changed"
i cannot figure out how to either successfully upgrade to snow or recover my system back to leopard. i dont want to clone and erase my disk since there are too much important data in there.

Same here, on a MB bought in December of last year, already running Leopard. It's currently bricked... totally annoying.

OK for what its worth here's what I did here and I think this really boils down to me being chronically impatient... 😉

First off, I learned that it's a REALLY GREAT IDEA to run Disk Utility, then Repair Permissions and Verify Disk (also Repair Disk if needed) before trying any sort of OS upgrade.

Also if possible try to avoid starting it and taking off for a couple hours - I did same, and I think my MB went to sleep and borked things since when I got back woke it up, it said "-30 minutes left" under the progress bar and failed.

Anyway:

1) Started installer on desktop. At 45 mins left, it suddenly rebooted and I got the apple with pinwheel for at least 5 mins. I figured it was "hung" and hard powered off. This is where the problems started. Pure speculation but I think what happened here was that I neglected to do Disk Utility + Verify Disk + Repair Disk before starting. On the reboot, it ran a fsck in the background. This can take a LONG TIME and suddenly cutting the power during this can give you problems. Filesystem is "dirty" due to poweroff, so you are going to get this every time now until that fsck can complete.

2) Powered back up, rebooted into CD, tried installer there, got Error "The contents of this disk cannot be changed". 🙂

2) Utilities -> Disk Utility -> Verify Disk (all other buttons were greyed)

3) This failed, but Repair became ungrayed so I tried that.

4) Failed twice in a row "Invalid inode map cannot repair" or something similar.

4.5) At this point you might try simply quitting the installer. It will prompt for the boot disk to use. Select your hard disk to stop it from booting into CD. You might get the pinwheel for a long time (say 15 minutes) while it does the fsck during bootup but you might get back to your system where you can try the install again.

This isn't what I did but in retrospect might work fine. Otherwise boot from installer CD again and:

5) Utilities -> Terminal

6) Command prompt (on macbooks your main partition is typically /dev/disk0s1, this will vary depending on your disk setup tho):

fsck -fy /dev/disk0s1

Failed: BAD SUPERBLOCK

then (note the following command could be dangerous ... use at own risk as a last resort, you could lose data, you have been warned):

fsck_hfs -pry /dev/disk0s1

(this did find a bunch of errors and tried to correct them)

...I don't know if anything here was even necessary though, and even
after all this I still could not mount the drive and fsck still gave
"bad superblock" errors.

7) Quit installer, it will prompt for which device to use as boot
disk. Select your hard disk to stop it from booting with CD.

8) At this point I was astonished to see everything come up OK!
Re-ran the installer, this time watching closely to make sure it
didn't goto sleep and waiting the full 10 mins it took for it to
reboot in the middle of the install. Actually I think the pinwheel
this time was much shorter since I had already run the commands above.

...all of this worked. Couple software updates and all is good.

Kappy wrote:
Snow cannot be used to upgrade Tiger.

The boxed set comes with Leopard and Snow.

Neither statement is true. Any retail copy of Snow Leopard will upgrade Tiger (10.4.x) directly to Snow Leopard (10.6). The boxed set contains exactly the same Snow Leopard installer disc as the stand alone product, plus two other discs, one for iWork '09 & one for iLife '09. It does not contain anything that installs Leopard (10.5).

The message "The contents of this disk can't be changed" typically indicates the disk targeted for the Snow Leopard installation is write protected, read only media like a DVD or CD in an optical drive, or some hard drive volume with incorrect permissions or extended attributes.

Make sure you have a backup but do not erase the drive. Run the Snow Leopard installer as described in the instructions furnished with it & make sure you are selecting the startup volume in the displayed volumes choices. If you then get this message, restart from the Snow Leopard installer disc (or just click its "Utilities" button), & launch its copy of Disk Utility. Run the "Repair Disk" step, followed by the "Repair Permissions" one. Then try the Snow Leopard installer again.

If you get the same error message again, or any message from Disk Utility indicating problems with the startup volume volume, report them here.

zeugmatis wrote:
First off, I learned that it's a REALLY GREAT IDEA to run Disk Utility, then Repair Permissions and Verify Disk (also Repair Disk if needed) before trying any sort of OS upgrade.

It can't hurt, but the Snow Leopard installer automatically runs the equivalent of Verify Disk on a target volume before writing files to it.

Also if possible try to avoid starting it and taking off for a couple hours - I did same, and I think my MB went to sleep and borked things...

Unlikely that this was the problem -- the installer also automatically sets the Mac not to sleep early in the install process. (Display sleep is not disabled, but that is not a problem.)

At 45 mins left, it suddenly rebooted and I got the apple with pinwheel for at least 5 mins. I figured it was "hung" and hard powered off. This is where the problems started.

The restart at about 45 minutes is normal, as are delays before & after the restart. A forced shutdown during this process is very likely to cause problems, because the delays occur while files written to the HD are being prepared for installation.

4) Failed twice in a row "Invalid inode map cannot repair" or something similar.

4.5) At this point you might try simply quitting the installer. It will prompt for the boot disk to use. Select your hard disk to stop it from booting into CD. You might get the pinwheel for a long time (say 15 minutes) while it does the fsck during bootup but you might get back to your system where you can try the install again.

Unlikely that this will help if you get this error message. Disk Utility uses the same underlying OS routines to repair the disk as fsck & if one can't repair the error, neither can the other.

6) Command prompt (on macbooks your main partition is typically /dev/disk0s1, this will vary depending on your disk setup tho):

fsck -fy /dev/disk0s1

This is unlikely to work because disk0 is the first disk in the device tree built at startup time. The "s1" part is the "slice" number, UNIX-speak for partition number. For the normal partition scheme for Intel Macs, while the internal startup drive will indeed usually be disk0, the partition containing the startup volume will be slice #2 (or higher). Slice 1 is the EFI partition, used during the boot process but not normally the one you want to try to repair.

then (note the following command could be dangerous ... use at own risk as a last resort, you could lose data, you have been warned):

fsck_hfs -pry /dev/disk0s1

(this did find a bunch of errors and tried to correct them)

...I don't know if anything here was even necessary though, and even
after all this I still could not mount the drive and fsck still gave
"bad superblock" errors.

It is likely (& fortunate) that this didn't do anything. As explained above, disk0s1 is (or at least should be) the EFI partition, which doesn't contain a file system of any type, much less one using the the hfs scheme. Are you sure you didn't mistake errors about the fsck_hfs utility complaining that there wasn't an hfs file system to repair as an attempt to fix anything?

8) At this point I was astonished to see everything come up OK!

Me too! 🙂

Actually, I think you might have been saved by the new installer's technique of writing temp files to the HD before it actually starts to overwrite the existing system. As long as the install process doesn't go too far before you stop (or abort) it, the existing OS remains unaltered & you can start up into it without problems, assuming you didn't force a shutdown that corrupted the file system.

So, while you are correct that impatience got you into trouble, it may have caused you to abort at a (somewhat) fortuitous time, at least as far as the integrity of the existing OS is concerned.

Yes, you can do it. [Here is a good example of a successfuly Tiger to Sno upgrade install|http://discussions.apple.com/thread.jspa?threadID=2185421&tstart=125]. Please give us more info so we can help you. e.g., How much space is left of your disk?

R C-R wrote:
Make sure you have a backup but do not erase the drive. Run the Snow Leopard installer as described in the instructions furnished with it & make sure you are selecting the startup volume in the displayed volumes choices. If you then get this message, restart from the Snow Leopard installer disc (or just click its "Utilities" button), & launch its copy of Disk Utility. Run the "Repair Disk" step, followed by the "Repair Permissions" one. Then try the Snow Leopard installer again.

If you get the same error message again, or any message from Disk Utility indicating problems with the startup volume volume, report them here.

Tried it and I got the following errors:

1. Veryfy Disk:
Invalid node structure
The volume Macintosh HD could not be verified completely
Error: This disk needs to be repaired. Click Repair Disk.

2. Repair Disk:
Disk Utility stopped repairing "Macintosh HD"
Disk Utility can't repair this disk. Back up as many of your files as possible, reformat, and restore your backed-up files.

What should I do? Is there a way to save the data on my disk? I don't have a backup unfortunately.

Hi aende;

The error message, Invalid Node Structure, indicates that there are extremely serious errors with the directory on that disk. I know of only two way to fix that. You can use DiskWarror to repair the disk or you can reformat the disk which creates a completely new directory.

Please remember that a reformat wipes out all data that is current on the drive so please backup first.

Allan

The situation aende described is what I too am seeing with my Mac Mini; the node structure error.

Aende - did you take either recommendation and if so what did you find?

Everyone else...
Before I attempt to use something like DiskWarrior, is there no way to save off some of my files? I looked at using Unix commands from Terminal to copy the files. It looks like it could be done but I'm guessing I cannot access the desired files when I've booted up from the SL install DVD ("-bash-3.2#" is what I see in terminal and I can't cd to anything like /Users/my disk/ or anything like that). Starting in Target Mode with my iBook G4 also didn't work. I saw the fire wire image on my Mac Mini but the volume never appeared on the G4.

About repairing the disk: is rEFit a good equivalent to the suggested DiskWarrior? The obvious appeal to me is that it is free.

Thanks everyone.

The invalid node structure error is usually fatal. 99.9% of the drives we've worked on required replacement. But that does not mean all of your data is lost. It simple terms it means the drive is failing and cannot be depended upon. If your still under your warranty, apple should replace the drive. Very important to remember Apple does not offer data recovery. This must be done either by the user or a 3rd party company before hand.

rEFit is very different from disk warrior. For a description, please see:
http://refit.sourceforge.net/

DW will attempt to rebuild the drive. It can be run from the computer having the issue or from a 2nd computer connected to the 1st. Unfortunately there is no free trail, etc., but it is still a worthwhile purchase for many reasons. *Your advised to backup your data, if you haven't already done so, before attempting to use DW, as any use of the Hard Drive could lead to further data loss. Simple guide for DW: http://www.ehow.com/how4563477use-diskwarrior-mac.html

If all you want to do is attempt to salvage as much data as possible off the drive, you might want to consider 'Data Rescue II'. This product offers a trial, so your able to see what you 'might get' back before committing to purchase.
http://www.theosquest.com/2007/05/05/data-rescue-ii-file-recovery-for-the-mac/

MacLovin