Securely free up space in Macbook harddrive by using SD card

We used Niftydrive with Sandisk 128gb UHS-I Micro SD Card and this config to allocate more space for Macbooks with small ssd drives. For 128gb and 256gb models this is a lot more space.

Save yourself the trouble and don't try to buy UHS-II cards since they don't have better performance vs UHS-I in Mac.

Please use Filevault encryption in your main hard-drive. This setup makes it easy to use Time machine backups to the contents of the SD card too.

Setup

First erase the partition scheme and use GUID. Then erase the partion on the sd card and split it into two parts:

1 insecure partition
1 encrypted partition

Open Disk Utility -> Choose SD Card -> Erase -> Use HFS+ (Journaled) and GUID

Then

Open Disk Utility -> Choose SD Card -> Partition -> Allocate 20-60gb for the encryption -> Use HFS+ (Journaled, Encrypted)

Reboot your machine after this and when prompted store the encryption key to secure partition in osx keychain.

In this example my secure partition is /dev/disk5 which is mounted in /Volumes/Minisecure and normal partition is /dev/disk3 which is mounted in /Volumes/Minidrive.

$ diskutil list

...

/dev/disk3 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *127.9 GB   disk3
   1:                        EFI EFI                     209.7 MB   disk3s1
   2:                  Apple_HFS Minidrive               63.1 GB    disk3s2
   3:          Apple_CoreStorage Minisecure              64.3 GB    disk3s3
   4:                 Apple_Boot Boot OS X               134.2 MB   disk3s4
/dev/disk5 (internal, virtual):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS Minisecure             +63.9 GB    disk5
                                 Logical Volume on disk3s3
                                 629361E0-1635-4287-8A76-6708D20A595B
                                 Unlocked Encrypted

Check where the disks are mounted:

$ df -h
Filesystem      Size   Used  Avail Capacity   iused     ifree %iused  Mounted on
...
/dev/disk3s2    59Gi  150Mi   59Gi     1%     38313  15362605    0%   /Volumes/Minidrive
/dev/disk5      60Gi  150Mi   59Gi     1%     38323  15571531    0%   /Volumes/Minisecure

Move Music,Videos,Torrents and cache directories to insecure partition

Consider these as safe things to store inside the sd-card even without encryption. If you have a really bad taste in music that should be encrypted as well. Also don't torrent anything illegal since those won't be encrypted with these configs.

$ export NIFTYPATH="/Volumes/Minidrive"

$ mv ~/Music $NIFTYPATH/
$ ln -s $NIFTYPATH/Music ~/Music

$ mv ~/Movies $NIFTYPATH/
$ ln -s $NIFTYPATH/Movies ~/Movies

$ mv ~/Torrents $NIFTYPATH/
$ ln -s $NIFTYPATH/Torrents ~/Torrents

# Create one cache folder for all cached images and libraries
$ mkdir $NIFTYPATH/cache

# Move composer cached libraries
$ mv ~/.composer/cache $NIFTYPATH/cache/composer
$ ln -s $NIFTYPATH/cache/composer ~/.composer/cache

# Move cached vagrant boxes
$ mkdir -p $NIFTYPATH/cache/vagrant.d
$ mv ~/.vagrant.d/boxes $NIFTYPATH/cache/vagrant.d/boxes
$ ln -s $NIFTYPATH/cache/vagrant.d/boxes ~/.vagrant.d/boxes

# Move npm cache
$ mv ~/.npm $NIFTYPATH/cache/npm
$ ln -s $NIFTYPATH/cache/npm ~/.npm

# Move wp-cli cache
$ mv ~/.wp-cli/cache $NIFTYPATH/cache/wp-cli
$ ln -s $NIFTYPATH/cache/wp-cli ~/.wp-cli/cache

# Move Homebrew cache ( This includes also Cask )
$ mv ~/Library/Caches/Homebrew $NIFTYPATH/cache/Homebrew
$ ln -s $NIFTYPATH/cache/Homebrew ~/Library/Caches/Homebrew

# Move spotify cache
$ mkdir -p $NIFTYPATH/cache/Library/com.spotify.client
$ mv ~/Library/Caches/com.spotify.client/Data $NIFTYPATH/cache/Library/com.spotify.client/Data
$ ln -s $NIFTYPATH/cache/Library/com.spotify.client/Data ~/Library/Caches/com.spotify.client/Data

Move Pictures to secure partition

I had no luck moving Pictures folder so I just moved everything inside of it and symlinked them. Please use encryption on sd-card if you want your photos to remain private.

# This only works in bash shell (or at least not in fish so using bash instead...)
$ bash
$ export NIFTYPATH="/Volumes/Minisecure"

# Move all directories inside ~/Pictures/ and create symlinks into their original paths
$ for file in ~/Pictures/*; do [[ -d $file ]] && mv "$file" "$NIFTYPATH/Pictures/$( basename $file )" && ln -s "$NIFTYPATH/Pictures/$( basename $file )" "$file"; done

Move Downloads to secure partition

If you don't have anything sensitive in Downloads you can use insecure path as well. This is just a precaution.

$ export NIFTYPATH="/Volumes/Minisecure"

$ mv ~/Downloads $NIFTYPATH/Downloads
$ ln -s $NIFTYPATH/Downloads ~/Downloads

Tell safari to use new path:

$ defaults write com.apple.Safari DownloadsPath $NIFTYPATH/Downloads

Move Dropbox to secure partition

This can be done in the DropBox settings as well and I think that's the recommended way. Use secure partition and choose /Volumes/Minisecure/Dropbox

Move Google Drive to secure partition

Move your Google Drive to secure partion.

$ export NIFTYPATH="/Volumes/Minisecure"
$ mv ~/Google\ Drive $NIFTYPATH/Google\ Drive

If you now start Google Drive it should prompt you that the Drive folder is missing. Then you can click and select new location.

onnimonni/niftydrive-sd-card-symlinks.md