How to increase the size (volume) of a share

I am getting a message that I have run out of space on the share I dedicate to time machine. How does one increase the size of a share. I have 3 TB of unused space on my Dropo 5N

The issue is that when you set up the time machine share, you have to choose a size for the sparcebundle that is created on the Drobo. The following is taken from Drobo Dashboard Help:

If you would like to dedicate this share to Time Machine backups, then select the Enable Time Machine support on this share check box and enter a value, in gigabytes, for the maximum size of the backup. To learn more about Time Machine, click on the appropriate link.

Note: If you decide at a later time to change the size of the Time Machine share, you will need to delete this share and create a new one to do so. It is best to create the new, larger share, move the data from the previous share to the new, larger one, and then delete the original share.

Usually, a Time Machine backup is sized to about twice that of the OS X System Volume that you are backing up. I have had mixed results when copying Time Machine data from one place (HDD, network share) to an alternate location. It might be better to just start fresh with a new Time Machine backup. If you are committed to preserving your Time Machine data, mount your Time Machine share using the afp protocol, and open the icon within the share. This will mount an image named “Time Machine Backups” on your desktop. Opening this image will reveal the Time Machine file “Backups.backupdb”. Using Finder, you can copy and paste this file into a new location — best to copy to an USB external drive connected directly to your computer. You can then delete the old Time Machine share and create your new one with the appropriate size. Then follow the same procedure to copy the “Backups.backupdb” file from your external drive onto the new share once you have mounted the “Time Machine Backups” image.

This is a lengthy task, and fraught with the risk of having errors in copying, so proceed at your own risk, and good luck.