You can backup multiple devices to the same Backblaze account, but you do need to pay for each device. That’s something you’d need to include in your decision making. There are two Macs in my household, both of which get backed up to Backblaze. It’s still a better choice for us than rolling our own, even at twice the price. We back up an eye-watering amount of data for two people, thanks to enormous libraries of digital media of all kinds. I keep adding drives; Backblaze keeps backing them up.
Backblaze can be reasonably speedy if you only need to restore a modest portion of the entire backup, which I’ve had to do myself from time to time. But if it’s mission critical that some files are always available no matter what, you may want a different solution.
I’m backing up double-digit TBs of data on Backblaze for the same price as I’d pay for a few GBs. What would be the advantage of a NAS in my case? Nothing I’m storing requires me to have uninterrupted access, which is why I might opt for some kind of RAID rather than cloud backup.
Even if you have unlimited cloud backup, depending on your internet speed there reaches a point where it is not feasible - especially for the initial complete backup and in the event you ever need a total data restore.
And depending on your internet provider, even if you have “unlimited” service your speed may be throttled when you try to do a multi-terabyte sized transfer.
And if your data is multiple Tb? Challenging via Internet.
MacBooks can have 8Tb storage nowadays. A Mac Studio can have 16Tb. Those are not realistic to backup via cloud.
On top of that - there are some forms of data where you need to be very careful with cloud storage. You cannot store an active/open Devonthink database in cloud storage for example.
Devonthink is one of the best reasons to get a NAS drive because it allows you to operate a WebDav server - which is a great way to sync Devonthink databases among different devices.
(1) I suspect you backed that up over time - not in one shot. Correct?
(2) What happens if you need to restore it all? Will that be via Internet or will they ship a drive to you?
If your Macs are 1Tb or less SSD size then Backblaze is probably realistic. If you use one or more Macs above 1Tb then there are probably benefits to a NAS drive.
If we were running a business I might make a different choice. Given that I’m not, I can wait for Backblaze to ship me a drive in the event I need to do a full restore. I do back up genuinely critical data to the portable SSD that lives in my go bag.
Since I don’t have somewhere I can put a NAS other than my home, I do really need a service like Backblaze to keep my files safely backed up offsite.
Knowing that there was a bunch of LTO tapes that could be onsite in less than an hour, as long as I didn’t get stopped by the police, was always comforting.
With regard to Devonthink’s implementation of WebDav it is rock solid. I have used it for years to sync DT databases among several Macs. Totally zero maintenance needed - “Just works.”
To be clear - I am NOT referring to Apple’s webdav server from the App store. I am referring to using Devonthink’s internal Webdav capability and Synology Webdav software on a Synology NAS.
As others have said - if your data is not critical (i.e. you are not running a business) and you can wait to receive a hard drive to restore data, then BackBlaze may be fine.
If access to your data is more time-sensitive then a NAS drive may make sense.