Normally Time Machine will use up much space as is available on the WD My Book Live hard drive. However, there is a simple fix to limit the size of any Time Machine backup volume, and it’s pretty easy to do on a My Book Live. Just replace the Time Machine sparesebundle with a custom size sparesebundle. Here’s how.
Set a Static IP
First, it is always a good idea to go into your router’s settings and give your My Book Live a static IP address. If you haven’t done this, I highly recommend it. I won’t go into details on how to do that here because if you don’t do this it’s not the end of the world. Just know that if the IP address of your My Book Live changes in the middle of a backup you may run into issues or have to start the backup again later.
Step 1 – Enable SSH on the My Book Live
You need to temporarily enable SSH on the My Book Live. If you don’t know what this is, don’t worry. You’re going to turn it off when you’re done.
Open your browser and enter in the address bar http://mybooklive/UI/ssh. If you have changed the name of your My Book Live, replace mybooklive with your name for the drive. In my case, I’d type in http://MyBookLive2TB/UI/ssh since I have renamed my drive to MyBookLive2TB. Alternatively, if you have given your drive a static IP you can use that in place of the drive name.
Once the page loads, check the box to enable SSH Access.
Step 2 – Create a Backup File
If you are already using your My Book Live for Time Machine backups you can skip to Step 3.
If not, open System Preferences > Time Machine and click on Select Disk. Choose your My Book Live Time Machine backup volume.
Start the backup and let it run for a few minutes so that the Time Machine volume gets created on the My Book Live, then turn off Time Machine backups using the Preferences pane (you don’t need to let the backup finish). It is important that Time Machine is off – you don’t want it to start up again until you’re finished.
Step 3 – Find Your Backup File
Open Terminal and SSH into your My Book Live using the following command:
or replace mybooklive with the drive’s static IP or whatever you have renamed it to. The password should be welc0me.
Again in your Terminal, type in
You should see a list of folders, one of which is your Time Machine sparsebundle (if you don’t, run your backup in Step 2 for a little longer). Remember the name of your own file…you’ll need it during the next step. I’m going to pretend yours is called Backup.sparsebundle…whenever you see that, replace Backup with the name of your own sparsebundle.
Step 4 – Create Custom Size Time Machine Sparsebundle
Open up a new terminal window and use the following command to create a new Time Machine sparsebundle. Here’s what you’ve been waiting for: the 250g means that this sparsebundle can only take up 250GB of space. Change this to whatever value you like. You’ll also need to insert your username and change the name of your sparsebundle to whatever it was called on your My Book Live in Step 3. The name of the newly created file must match the one found on your My Book Live in Step 3.
hdiutil create -size 250g -fs HFS+J -volname “Time Machine Backups” /Users/USERNAME/Desktop/Backup.sparsebundle
The file will not take up 250GB on your computer (it will probably use up less than a GB of space), but it might take a moment for it to be created.
Step 5 – Replace Your Old Time Machine Backup File
Drag your new sparsebundle to your My Book Live drive. It doesn’t really matter where. Your Public folder is a good option. Once it’s there, open up the terminal window that you used to SSH into your My Book Live. Use the command below to replace your old Time Machine backup with your new sparsebundle. Remember to replace Backup.sparsebundle with the name of your own Time Machine sparsebundle.
rsync -a –progress /DataVolume/shares/Public/Backup.sparsebundle /DataVolume/backup/TimeMachine
This could take a while. Do not proceed until the rsync is complete.
Step 6 – Turn on Time Machine Backups
You can delete the sparsebundle in your Public folder. Go back into Time Machine in System Preferences and turn on backups again. If a backup doesn’t begin, force a backup by clicking the Time Machine icon in your menu bar. If you get a prompt about the identity of the backup disk changing, click Use This Disk. That should be it. Let a full backup run. If everything is OK, go back to the URL in Step 1 and disable SSH access on your My Book Live.