MacOS – How to mount ufsd_NTFS partition

You should parse the output of hdiutil, and mount the filesystems you're interested in - because you can't do what you're trying to do with mount.

The first few lines of the man page show supported syntax:

 mount [-adfruvw] [-t lfs | external_type]
 mount [-dfruvw] special | node
 mount [-dfruvw] [-o options] [-t lfs | external_type] special node

Notice for -a, there are no options to specify a node path, which makes your command invalid syntax.

(Also, I'd suggest testing with a proper image file - one that is an actual CD image. Your image is a hard-disk type, with an Apple Partition Map, and no non-HFS partitions. In Disk Utility, choose New -> Blank Image and note all the selections carefully. You want "CD/DVD"; you can then edit the partition map after you've created it; say, to change to two partitions.)

I would try the following since all basic configs/lists/outputs look fine:

• boot to Single User Mode
• /sbin/fsck -fy

• Display free disk space /bin/df

  Example:

  Filesystem  512-blocks        Used  Available Capacity   iused     ifree %iused  Mounted on
  /dev/disk2  6066780416  5644868776  421399640    94% 705672595  52674955   93%   /
  

  Here 94% of the disk space and 93% of the inodes are used.

• If free disk space ~0 /sbin/mount -uw /

• Change directory cd /Users/user_name/path/to/big/file and list files with ls
• Print working directory to be sure pwd
• rm big_file
• Display free disk space again /bin/df
• boot to main volume with exit

You may have to remove some really small files (size < 100 kb) first before you succeed deleting the big file.

If this fails get an external disk, partition and format it (JHFS+) it in Recovery Mode or with a second Mac. Attach it to the broken Mac, boot to single user mode (cmdS while booting), mount the external drive and rsync your user folder and other important files & folders to the external volume. Then erase Macintosh HD and reinstall OS X. You may also rsync your complete system!

Mounting an external drive to /Volumes (even though the boot drive is readable only) should be possible by using:

gpt -r show disk0/1/2 #search for the proper drive because *diskutil* won't work in SU mode
/sbin/mount_hfs -o nosuid -w /dev/disk2s2 /Volumes/ #mount the external drive (e.g. disk2s2) to /Volumes
rsync -aAvX /Users/user_name/ /Volumes/user_name #Backing up the user folder. 

If the above rsync options don't work use something like rsync -aE ... instead.

The root of the external drive is directly in /Volumes (so no volume name in-between like on a normal system: /Volumes/Volume_name_ext_drive/).

After rsync'ing check the content of the "new" user folder.

(Tested in a VM)