Hello guys,
So currently having only one TrueNAS server which holds some crucial data. I’m planning to setup a backup server. How do I do that and most importantly, how do I determine the storage size of the backup server? Does it has to be larger than the current server?
Any suggestions are welcome 
It doesn’t really have to be bigger than your existing server, it could even be smaller!
It mostly depends on your risk tolerance. Do you have only mission critical data that you absolutely must backup, or do you have some mission critical data mixed in with data that you can afford to lose (media etc)?
If it’s the former, then make it as least as large as your current server (though it may be cheaper to store this somewhere like Storj or Backblaze). Perhaps on this backup system you’ll want to keep snapshots for significantly longer, so you might want to up the total storage capacity in line with that.
If it’s the latter, you could get away with a smaller system and replicate only the data that you absolutely can not afford to lose. In my case, that’s under 1TiB, so a backup server for me would be significantly smaller than the 100TiB or so total capacity that I have.
