To be able to advise you we will need to know your regular backup strategy. How are you backing up your mac? Are you using Time Machine?
Then you could simply include your Aperture library and your external drive with the masters/original image files into regular Time Machine backup.
For added safety (you really should have more than one backup of your photo library, if your photos are important to you) it is useful to make a clone of the disk with the original files and to update this clone occasionally. As a second backup of your Aperture library a vault is useful. This will store the library itself, but not the referenced originals.
How do I organise them/ back them up?
You do not organize your referenced image files - let Aperture do it and let the originals exactly like Aperture stored them. And make the backup of your masters an exact copy of this folder.
Will I end up with one huge project if i create a new library from the masters on the external hard drive?
If your computer should fail and you need to restore your Aperture library, you need a backup of both your Aperture library and of the masters/originals.
Restore the folder with the original masters to a similar location on an external drive, restore the Aperture Library from your Time Machine Backup or a vault, and then you can reconnect the image versions in the restored Aperture library to the restored originals. The library will be exactly as before. You do not have to import the original masters and to start all over again.
Thanks for the response and help!
Up until now I was backing up on timemachine on a 1tb drive. I have 3 hard drives, two 1tb and one 500gb. I was using one of the 1tb for timemachine.
I bought a new 1tb where i have placed all the relocated masters on it.
I was thinking of deleting the timemachine back up, on the old 1tb and starting it afresh so I can use the old 1tb to back up the aperture relocated files.
I dont think i really need the old timemachine backup since i have relocated my masters.
Then I was going to to timemachine backups on the 500gb drive, so that i have a copy of the aperture library and all its projects.
1tb- relocated masters
1tb- backup of relocated masters (Do i just copy and paste from one drive to the other? )
500gb- timemachine backup of whole computer/ aperture
Do you think this makes sense?
Also you say: Then you could simply include your Aperture library and your external drive with the masters/original image files into regular Time Machine backup.
I thought timemachine would not back up relocated files stored on an external hard drive?
I was also wondering about the folder of my relocated masters which consists of 25,000 photos. All have the same name SDW panorama 1, then 2, 3 etc. This is because i relocated all my projects at once. Since then, i have relocated a new project and this is now stored in a folder of its own in the same file as all the other relocated photos. As you said though I shouldnt touch them and leave everything as they are? I thought about remaning all the files and having them all in the one folder.
Dont know anything about vaults within aperture or if they could be useful for me?
Thanks again for your help!