Drobo up and Running

I finished two more Macs tonight before I left.  It looks like the Drobo and Time Machine are both happy.  I ended up using a tool from the backmyfruitup project (a project to add afp:// access to a Drobo) to create the sparsebundles and it worked really well.  I also tried it from the command line with limited success just to see if I could do it.
The command to create the sparsebundle is

hdiutil create -nospotlight -imagekey sparse-band-size=262144 -size 600g -fs "Case-sensitive Journaled HFS+" -volname "Backup of $HST" ~/Desktop/${HST}_${ETH}.sparsebundle

Where $HST is the computer name ( networksetup -getcomputername ) and $ETH is the mac address without punctuation ( ifconfig en0 | grep ether | sed s/://g | sed s/ether// ).  This version creates a 600G bundle with 128M chunks. Then run the famous hack

defaults write com.apple.systempreferences TMShowUnsupportedNetworkVolumes 1

to get Time Machine to see the Drobo.
Snow Leopard requires a file inside the sparsebundle:

$cat com.apple.TimeMachine.MachineID.plist
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
 <key>com.apple.backupd.HostUUID</key>
 <string>UUID_STRING</string>
</dict>
</plist>

Just replace UUID_STRING with the Hardware UUID found in About This Mac -> More Info -> Hardware. Unmount the volume and copy it to the Drobo. Launch Time Machine and tell it to use the Drobo, enjoy the countdown to launch, and leave for the night once it starts backing up.