sudo apt-get install hfsprogs

## NOTE is saw that we should disable journaling on the external drive before writing with Linux

sudo mount -t hfsplus -o force,rw /dev/sdXY /media/mntpoint
# or
sudo mount -t hfsplus -o remount,force,rw /mount/point

1. Attach flight drive to archive CPU
2. Attach mirror drive to rsync to (either HFS+ journaling disabled or EXT4)
3. Attach archive drive which will get the compressed mjd tar file for each day
4. rsync the flight data to the mirror drive (directory by directory at top level)
5. run compress script (see below) to generate a MMMMM_0.tar.gz for each flight day on the archive drive

later you can add MMMMM_[1-z].tar.gz for any additional files that were missed?

lvis@lvis-dell-xps:~/bin$ more compress_all_mjd.sh 
#!/bin/bash
 
echo "Usage $0 <input dir> <output dir>"
 
M_INPUTDIR=$(echo $1 | sed '/\/$/! s|$|/|')  # add a slash if necessary
M_OUTPUTDIR=$(echo $2 | sed '/\/$/! s|$|/|') # found online
 
echo Input: $M_INPUTDIR
echo Output: $M_OUTPUTDIR
 
cd $M_INPUTDIR
for f in *; do
    if [ -d "$f" ]; then
        M_BASENAME=$(basename $f)
        re='^[0-9]+$'  # check if this is a just a number (day mjd) (found online)
        if [[ $M_BASENAME =~ $re ]] ; then
           M_TARFILE="${M_OUTPUTDIR}${M_BASENAME=}_raw_data.tar.gz"
           echo "Run on $f which is $M_BASENAME"
           time tar cf - $f | pigz > $M_TARFILE
        fi
    fi
done

• https://csatlas.com/mount-tar-file-ubuntu/ ← archivemount HOWTO

Options we might be interested in

       -o readonly
              disable write support

       -o nobackup
              remove archive file backups

1. Install if not already on the system

   sudo apt install -y archivemount

2. Create a mount point

   mkdir /tmp/myfiles

3. Mount the tar file as read only

   # read / write mount which makes a .orig file
   archivemount myfiles.tar.gz /tmp/myfiles
   
   # read / write mount without any backup
   archivemount -o nobackup myfiles.tar.gz /tmp/myfiles
   
   # read only
   archivemount -o readonly myfiles.tar.gz /tmp/myfiles
   

4. Read data out of archive as if it were a file
5. Remove the mount

   cd && umount /tmp/myfiles