Can't get Time Machine to work with Nighthawk

Based on this page https://ss64.com/osx/tmutil.html , it looks like tmutil may overwrite the current configuration for the new one, but I don't believe that it would mess up the old backups or anything, just point the primary towards the new volume. HOWEVER, reading that page, it may be possible to have multiple destinations using the -a flag. 

So something like:

`sudo tmutil setdestination /Volumes/TimeMachine1/` for the first destination and then

`sudo tmutil setdestination -a /Volumes/TimeMachine2/` for your newly created drive.

Again, I have no idea how that works in practice as I've never seen it, but it does look like that is supported in some capacity.

Thanks very much for the reply. i don't understand why the images would be blank for you but obviously I am doing some wrong. PEBCAC. They seemed to upolad correctly and I see them properly when I follow this thread. I will need to investigate further.

I am trying to have a 2nd, redundant, Time Machine backup that my MacBook can alternate between.

I really apprreciate you clarifying the Terminal command. I will run that and see what happens. Perhaps if the command can sort that the sparse image is a valid location it will remove it from TM's privacy pane.

Thanks again.

At the moment Time Machine is backing up to my 2nd drive . I say "at the moment" because I do not know if it will smoothly rotate to my other, original backup drive. I suspect I will confirm that tomorrow.

In the meantime, some updates to how this worked for me in relation to the guide posted by wkuchrisn

First, this is my experience at Step 3 - Time Machine Setup

I somehow missed your post regarding using the -a flag.

Hopefully this will continue to work. Here is what happened.

I had the sparse image mounted and then ran the initial Terminal command. When I then went to Time Machine preferences it had selected the mounted sparse image as the Time Machine destination. I was now in a bit of a panic. While it would not erase my original Time Machine backup it would be somewhat challenging to re-connect the original Time Machine backup without losing all my backups.

Fortunately, as soon as I clicked the button to choose a backup disk I was immediately prompted by Time Machine to confirm if I wished to use the selected disk, my sparse image, or if I wanted to use both disks, the other being my existing Time Machine backup drive, and rotate between them. One hurdle avoided. I selected both then followed the rest of your guide for Step 4 - "Router Setup" and Step 5. "Mac Setup (aka Return of the Mac)."

Everything clicked along nicely with these following exceptions in Step 5, sections d and e.

Section d:

I noticed when logged in to my router and looking at ReadyShare it showed the T_Drive as having the correct amount of storage space. However, the USB_Storage only shows a small amount of storage. In my case it displays 196.9MB. It would seem that is due to the size I chose for my sparse image, which is the amount of storage space shown for the T_Drive. I did not try and find out if it mattered and selected the T_Drive as you suggested.

Using the reboot option in the router's Advanced settings failed to show the newly connected drive in my setup. I also have a Netgear Ethernet switch so decided to unplug both my router and the switch and reboot them that way. As soon as I was back online the new drive mounted through my router and showed in ReadyShare.

As I said at the start, at the moment Time Machine is smoothly performing its first backup to the sparse image so I am pretty thrilled right now.

Thanks again for the guide and assistance along the way. I will post an update as soon as I know if Time Machine correctly rotates to the other drive.

The two backups have, so far, been humming along nicely, switching back and forth every hour. I ran a check with "The Time Machine Mechanic - T2M2" and it shows zero errors.

This is great news at this stage and again I am most appreciative to wkuchrisn for the help along the way.