enhancement - readme - notes for consideration on creating disk image dd/ ddrescue

[johndpope]

Back story
So from testing out different recovery software - I think I reduced chances of successfully recovering files - so a pointer for new users to create an image of failed drive I think is important. I tried using clonezilla 2nd time, again last night to create another backup / but this time it failed. (was trying to spit out file to ntfs drive as dmg /dd file directly rather than cloning drive)

I guess a simple dd of failed drive might be easiest but reading through this morning though - https://medium.com/@peterburkimsher/saving-a-friend-with-apfs-data-recovery-89cffaabdadd ddrescue which also provides a log / and pointers to failed /bad sectors will help more than dd out of the box.

Precautions When Cloning with ddrescue
ddrescue is a powerful utility and should only be utilized by experienced Linux users. It can cause damage to a failing hard drive in some circumstances. It can also overwrite data when used incorrectly. If you really need your data and your hard drive is failing, your best bet is a professional data recovery service. https://datarecovery.com/rd/how-to-clone-hard-disks-with-ddrescue/

Using ddrescue will provide a log that will allow you to capture bad sectors.
It can also recover from interruption.

Why this issue / I think there's a lot of people with failed APFS drives from Apple discussion boards + stack overflow. Searching google yields a few pieces of software / iboysoft /disk drill and youtube videos saying run this software and everything will be fixed. After wasting days on this - it would have been better approach to know the best approach. I believe this approach of reading through apfs is superior / needs to be performed on disk image. Just need a pointer on best way to create this.

[johndpope]

N.B. - this software is neat / it can stop drives from auto mounting.

[johndpope]

a couple of notes -

This command will peek into the DMG's partitions:
hdiutil pmap your_file.dmg

The drive should be readonly when mounting - not sure best way to do this. This post mentions using shadow hdiutil attach -owners on Moby.dmg -shadow

https://superuser.com/questions/494916/cant-mount-dmg-image-as-read-write

[johndpope]

I'm sensing that as a sanity check before running mmcat / the dmg should check out as ok.

hdiutil pmap /Volumes/ELEVATE/errorFree2.img
asr imagescan --source /Volumes/ELEVATE/errorFree2.img

hdiutil mount -nomount -readonly /Volumes/ELEVATE/errorFree2.img