Backup Image Fails to Mount

[eighteesix]

I've been backing up my HDDs using disk utility (creating images from drives). everythings been going great for a year. however, ive hit a snag. my 2 drives data drives (formatted as MacOS Journaled) mount fine on my macbook pro, but both of my backups of my main osx (10.7) drive will not mount. i get the error "no mountable file systems". how the hell is it that they are both bad? how do i fix it so i can mount one? i know the files are good, there must just be some minor issue--and i really need these files.

ive read that using repair from disk utility can work. this does not work. should i try diskwarrior? ive heard this only works some of the time.

 

[eighteesix]

Update: Problem persists, but I found a workaround--sort of. I used diskwarrior to access the drive. First I opened Disk Utility, attempted to mount the drive, and when the error about no mountable file system came up, i left it open (leaving the disk "Mounted"). then diskwarrior was able to find it. i used the "rebuild" feature. i then previewed the disk and was able to copy all my files, but after rebuilding it still wont mount.

why is it that my hard drives with data but no OS will mount, and my hard drives with data and OSX will not mount? all formatted mac os extended.

 

[Dave Braine]

Do I take it that you are trying to boot from your backup? I'm pretty sure that you can't do it from a disc image.

If you want a bootable backup, then use either Carbon Copy Cloner or Superduper and make a clone of your HDD. This will be bootable.

 

[eighteesix]

not trying to boot from. the image is on an external hard drive and im just trying to mount it after plugging in the external. it will not mount.

i erased the startup OS on purpose, and i didnt expect this issue.