C-Command Software Forum

Damaged Disk Image

I’m trying to create a DMG of a CD using DMG Read Only.

Running 10.5.2. v2.8.4 of DropDMG.

I receive this error when trying to mount the image created:

“The disk image you are opening may be damaged and could damage your system. Open/Don’t Open”

If I click Open, it appears to be OK. When I click don’t open, the error mentioned is “No Mountable File Systems”

From Console…
2-15-08 3:36:11 PM diskimages-helper[6885] /sbin/fsck_hfs(/dev/disk2s2) failure for /Users/tom/Desktop/Filename.dmg.

Any ideas?

I’m not seeing that problem with DropDMG and 10.5.2. Is there anything you can tell me about the CD that you were imaging? Does it work for you if you create a read-write image or if you use a different CD?

Probably not DMG issue
So I tried creating a empty dmg first and drag my files from the CD over. It chokes on an installer file (.pkg) saying “The alias “app name” cannot be copied to the destination, perhaps because the destination does not support this type of alias”.

A bit bizarre so I zipped up the file, copied to the dmg and then unzipped it. Unmounted, and remounted and it works fine.

Has something to do with this installer and not DMG.

repair damaged dmg
In your case , I doubt you didn’t solve rhe problem yet , but there is something that can be done
It’s a trick that I discovered trying to recover a bad hdd

  1. download Diskwarrior for mac

  2. open diskwarrior (it will not see your image yet )

  3. try to open the .dmg

  4. When the message “The disk image you are opening may be damaged and could damage your system. Open/Don’t Open” appears return to diskwarrior who now will see your quite monted .dmg
    5.Rebuild catalog on that volume

Now your image will should mount

a simple fix
first of all don’t panic
the disk image is probably not damaged
and will probably not damage your system

this error message was introduced in tiger
think of it as a sort of spell-check for disk images

a proper disk image should have a specific file structure for it’s file type
if the disk image you are trying to mount has a mixed or outdated file structure
you will get this error

i most commonly see this error when i am mounting a dmg file that was created by a ‘dumb’ conversion of a toast image

toast creates certain invisible desktop files which it needs to mount an image

these files are not needed and don’t belong on a dmg image

here’s how to fix it

convert the dmg file to a read-write format

mount the r-w dmg [ignore any errors]

examine the contents of the root level of the mounted image in a list view with “filebuddy” [from skytag software]

delete un-needed invisible desktop files

unmount the image

convert it to read-only uncompressed
[uncompressed images will compress much smaller if you are going to compress the finished image]
[rar often produces much better compression than zip]

mount the new dmg

if you deleted the right files, the dmg should mount without error

as far as copying errors is concerned -
“I tried creating a empty dmg… and drag [ing] my files from the CD…It chokes on an installer file (.pkg) saying “The alias “app name” cannot be copied to the destination, perhaps because the destination does not support this type of alias”.”

this is a permissions error
os x 10.4+ is permissions crazy

you can try checking “igore permissions on this volume” in the the finder’s “get info” window
but the best way is to make a read-write dmg of the mounted disk and follow the proceedure above

as an alternative you can create a cdr image which is read-write by default and then convert it to dmg using the proceedure above