Ghetto Fusion Drive on Old Macs OS X

fusion_test.sh

#!/bin/bash

# Based on http://jollyjinx.tumblr.com/post/34638496292/fusion-drive-on-older-macs-yes-since-apple-has
# To use this, first create a corestorage drive - see e.g. http://www.cnet.com/how-to/how-to-make-a-custom-corestorage-drive-in-os-x/
# -- it'll look something like this:
#
#    diskutil list        # and figure out which actual drives you want to join
#    diskutil cs create FusionGroup disk0 disk2  # or whichever two drives
#    diskutil cs list     # and note the Logical Volume Group ID 
#    diskutil cs createVolume GROUPID jhfs+ Fused 100%
#
# Then to make sure it's working like a Fusion (and not just a conjoined virtual drive),
# run this script in one Terminal window (assuming you named your new drive Fused):
#    ./fusion_test.sh /Volumes/Fused
#
# In another Terminal window, run iostat:
#    iostat -d 1
#
# During the first phase, you should see writes on your SSD until about dir 12,
# then it should switch to your HDD.
#
# When the script asks you to hit return, wait until activity dies down.
# During the second phase, we continually read the files that were originally written to HDD.
# Reads should happen from the HDD for a while. Wait for a few loops.
# Then hit control-Z to pause this script and watch the iostat window.
# If Fusion is really working, then you should see activity on both drives
# as CS shuffles the files between HDD and SSD for a few minutes (maybe 10).
# Then type "fg" to resume this script. 
#
# Watch and repeat a few times.
# Eventually all reads should happen from SSD.
#
# When you quit this script with control-C, it will delete all the temporary files.

# I used Mavericks and two external drives -- a Thunderbolt SSD and a USB 3.0 HDD -- and Fusion appeared to work okay.

# We create directories 00 to 13 with 100 files each 100 Mbytes in size
# -- about 140G. (If your SSD is 256G then change 13 to 25)

if [[ -z "$1" ]]; then
  echo "Usage: fusion_test.sh dir"
  exit 1
fi


mdutil -i off $1   # turn off Spotlight indexing on the volume

written="0"
base="$1/bogus"
mkdir -p "$base"

function clean_up {
  echo
  echo Exiting...
  rm -r "$base"
  exit
}

trap clean_up SIGINT

for d in {00..13}; do
  mkdir -p "$base/$d"
  for f in {00..99}; do
    mkfile 100m "$base/$d/$f"
    written=`expr $written + 100`
    echo -ne "Wrote ${written}m\r"
  done
done
echo

echo -n "Press return to start reading>"
read 

echo -ne "Reading "
while `true`; do
  for d in {12..13}; do
    for f in $base/$d/*; do 
      echo -ne "Reading $f \\033[0K\r"   # clear to eol, then cr
      dd if=$f of=/dev/null bs=1m 2>/dev/null
    done
  done
done

More references for setting up a Ghetto Fusion Drive on older Macs:

• http://jolly.jinx.de/teclog/2012.10.20.fusion-drive-on-older-macs-yes.html
• http://www.macworld.com/article/2014011/how-to-make-your-own-fusion-drive.html
• http://blog.macsales.com/17624-os-x-10-8-3-provides-fusion-drive-setup-option-for-non-fusion-drive-equipped-macs
• http://www.instructables.com/id/Pimp-your-old-Mac-Pro-with-a-Fusion-Drive/
• http://benscheirman.com/2013/11/creating-a-fusion-drive/
• https://www.google.com/search?q=Fusion+drive+on+older+Macs&oq=Fusion+drive+on+older+Macs