Hello. The forum will want more info about your current setup (archive/db on same machine? # of Users?, etc.) - in the meantime, saving to the cloud is straight-forward. The archive server is backed up just like any other machine - just point the location for the backup to the cloud instead of a server in the building. Ditto for the registry settings for the database server (if it's a different machine). Finally, SQL needs to be backed up. There is a facility built into SQL for backing up and there are several online references on how to b/u SQL.
Also, don't forget those backups need to be tested - frequently. The more you test, the easier an actual disaster recovery will be.
Hopefully you'll get plenty of posts from ppl already doing it. There are many services available. Also don't forget there are cabinets rated for fire/theft to drop the backups into if saving to a NAS or other device outside the building doesn't make sense.
I know of a company that keeps a replicated archive server in the basement of the owner.
Nobody really connects to that machine, but files are pushed to it every night.
I think it is a rather econimical solution. It doesn't cost anything additional for EPDM, and the computer being used is an old design machine with a pretty nice hard drive.
(I think they are using more traditional methods of backing up their SQL database.)
This is probably the best 'cheap & easy' way of doing it... The Archive Server keeps it's backup for you and then all you have to do is backup the SQL database(s) and transfer them to the same Replicated Archive Server. As the backup Archive Server would not be used to access the files except in the event of recovery then it can be a very low end machine. That said - I would still put in a redundant (mirrored) system / data hard drive.
Note that using 'Cold Storage' to remove old versions could cause issues using this method.
Of course - monitoring & testing is the key. Make sure that any backup method is actually running, is working and can be restored.
We don't use any PDM, but we do backup our data to external drives, and store them offsite.
Look up the some info on the percentage of companies able to fully recover from an in house disaster, not something fun to read.