The first time you run a Time Machine backup on your Mac, a sparse bundle is created on your ReadyNAS to store the backup data. The maximum size of the sparse bundle is the size that you specify when you enable Time Machine on your ReadyNAS.
After you run Time Machine for the first time, the size of the sparse bundle that stores your Mac backup data is fixed. If you want to increase the size of the sparse bundle, you must delete the sparse bundle and create a new Time Machine backup.
To increase the capacity of the Time Machine backup on your ReadyNAS:
1. Ensure that the AFP file-sharing protocol is enabled on your ReadyNAS system.
2. In Finder, select Go > Connect to Server.

The Connect to Server dialog box displays.
3. Enter the following command in the Server Address field:
afp://<hostname>
<hostname> is the name that you assigned to your ReadyNAS system or the default host name if you did not change it.
Note: If you cannot access the ReadyNAS using its host name, try entering afp://<ReadyNAS IP address> instead. <ReadyNAS IP address> is the IP address of the ReadyNAS.
4. Click the Connect button.
You are prompted to log in to your ReadyNAS system.
5. In the Name field, enter ReadyNAS.
6. In the Password field, enter the password that you created when you enabled Time Machine on your ReadyNAS.
7. Click the Connect button.

You are prompted to select a volume. Mac OS X calls your ReadyNAS shared folders volumes.

8. Select timemachine and click the OK button.
Finder displays the volume contents.
WARNING: Deleting the sparse bundle deletes all Time Machine backup data stored on your ReadyNAS.
9. Delete the sparse bundle file ending in .sparsebundle.
10. Create a new Time Machine backup and specify a larger capacity.