Creating disk image - permission denied

I had a similar issue trying to create a Blank Disk Image. However, I was getting the "permission denied" trying to create it even on the Mac HD. I knew I could create folders, read/write, etc. and I had plenty of space. I didn't even notice the lock thing until seeing it mentioned on here. The discussion about the "lock" on the drive got me to go to Finder to look at the drive, do GetInfo on the Mac HD drive, and sure enough it was locked.

I wasn't sure how to run the commands that jsd2 linked to, but I was able to click on the lock icon, enter my admin password to unlock it, then select my user account and give it read/write access to the Mac HD.

If apple is listening, or if others who are unfamiliar with the platform like me are looking, it seems rather odd to me that I could have only "Read" access to my Mac HD, yet be the admin account. Moreover, the lock only appears on the drive in GetInfo, not on the icon or somewhere else obvious. Then the last frustrating thing is that the Disk Utility just gives you the cryptic "Permission Denied" without any hint or explanation or anything. Frustrating. And nothing in Help about possible issues leading to that error message either.

Thank you all for the discussion though, as it led me eventually to a solution without schlepping my system over to the Genius Bar for another 7 second beatdown for the new guy.

Hi,

I think we may be dealing with an apples and oranges situation here... 😉

The "lock" on the external disk volume discussed earlier in this thread represents a special flag on the volume itself, which prevents any changes to its top level. It normally shows itself by displaying a small padlock on the item's Desktop icon:

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If the locked item is a disk volume, then its locked status doesn't show up in Get Info at all, and you need a Terminal command to remove it. The same kind of "lock" on a file or folder does show up in Get Info, but as a checkbox in the General section, not in the Sharing and Permissions section:

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This type of lock overrides any write-permission that is set in the Sharings and Permissions section.

By contrast, it sounds as if the "lock" you were referring to is instead the padlock icon at the bottom of the Get Info window. This icon is unrelated to the presence or absence of the "locked" flag discussed above. The padlock icon at the bottom refers only to whether or not the user has the current ability to make permission changes, not to the actual state of the item. If that padlock is locked, it can be unlocked with an admin password, but this by itself doesn't change anything on the item - it just gives the current user the ability to make permission changes.

As an aside, it's not a good idea to mess with the permissions on the top level of your startup drive, and a user should not normally be storing things there anyway. In Snow Leopard an admin user normally does have permission to write to the top level of the startup drive, but this was deliberately changed in Lion, removing write-permission there for all but the system.

So, self-admittedly, I would be the orange...

Thank you for describing this in more detail for me, i think it makes more sense. Let me see if I have it all right.

I was trying to create a new sparse image file on my Mac HD. If I do GetInfo on the Mac HD, it doesn't have that little "Lock" square to check. There is only the permissions below. As I said, it was "Only Read" for even the admin account.

You are correct, the little Lock icon at the bottom just allowed me to make the change to the Read/ Read and Write status.

It sounds like what you're telling me is that I SHOULD NOT set the Mac HD to allow me to write to it only because it is the top level, and that if I had tried to create the Sparse Image files in a subdirectory, like on the desktop, it would have worked. And in fact it does.

Being a PC guy, there is nothing sacrosanct about the top level of the C:\ > drive, so when I was creating some heavy use image files to mount as different drives, it didn't occur to me not to create them at the root, but that seemed like the logical place to put them. I don't have Lion, I have 10.6.8 (doesn't say which animal) but my permissions were locked for the top level. I've now re-locked them, per your recommendation, and moved my image files to the Desktop.

So, as usual I did this to myself, but thank you for the helpful clarifications and I'm now back to loading up my images with stuff.

if I had tried to create the Sparse Image files in a subdirectory, like on the desktop, it would have worked.

Well, more specifically, items you create should normally be saved either within your Home folder or within the Shared folder. Items you create on the Desktop go into the Desktop folder, which is fine because it is a subfolder of your Home folder.

Alas:

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