Backing up external drive to NAS from multiple PCs

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Backing up external drive to NAS from multiple PCs

Operating system
  1. macOS
Mobile operating system
  1. iOS
Sorry if I missed it, but I didn't see any discussion of this in the existing threads. I've got an external disk which holds my photo library and photos. I back it up to my Synology NAS with a Synology Drive Client backup task, and then it's backed up to Backblaze from the NAS. I use the external drive with a desktop and a laptop when I'm traveling and taking pictures.

My question is: is it safe/effective for both PCs to run the same backup task? Will it recognize the state of the backup correctly when each one runs, or will I end up with two copies or end up unnecessarily re-backing up everything because the clients don't have the right state?

Considering you are running a Drive backup task the questions here is are you using the same DSM user in both instances?

If so then your destination backup on the nas will hit the same location.

Drive will handle duplicate data and if your pc/laptop uses the same file/folder structure, guessing it does if you are using the same drive, then it shouldn’t be any difference on the destination side.

Still, not something I’m 100% sure as I don’t use Drive in that similar scenario.
Thanks! It will be the same user, and the location makes sense. I'll give it a try and see how it behaves.
Following up on this thread with what I learned from experimenting further with this.
1. This won't work as I hoped using Synology Drive Backup, because the Backup location is qualified by the source computer, so the backups from the two devices would end up in different places, and there would be two copies.
2. Switching to a Sync job rather than a Backup task might have worked and allowed me to sync to the same location, but see items 3 and 4.
3. My initial backup task failed silently, it went through "preparing" for every file, but never managed to transfer anything. I had to check the diagnostic log to see that it was logging errors for every single file. No idea why the failures were occurring, but deleting and recreating the task and restarting Drive produced a task which was actually backing up.
4. Performance was so painfully slow that the 1TB backup was not going to complete in my lifetime. It never used more than 200KB/s of the bandwidth available. Between this performance and the silent errors, I have lost faith in Drive as serious backup software

I've since switched to Carbon Copy Cloner and expect that this will work fine from the two devices, since the source and target are fully configurable. It's also getting ~70MB/s backup throughput, and will be done with the first backup in about 6 hours.
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CCC, ForkLift, DriveDX, OSX Disk Utility Raid Assistant, and (if needed) SoftRAID are basic time-proven tools for the Mac environment that just keep getting better over the years. Ron
For the slow witted (me), what you are doing is using one external USB drive to store a photo library. This USB drive is used interchangeably between two Macs* as the fancy takes you.

The main objective is that either Mac can run a task that can backup the USB drive's contents to the NAS, and that there is only one backup destination used by the Macs.

This is right is it?

As you seem to have found out, CCC will do this provided you have defined the tasks exactly the same on each Mac. I would advise to enable SafetyNet so that any deleted files and folders are retained in a _CCC SafetyNet folder on the NAS. You can prune it manually if you like and also have an automated setting in the task. Depending how you organise photo storage you may want to use a few tasks so that one could work on finished photo files using the Don't Delete Anything option in SafetyNet.

I have used CCC 4, 5, and 6 and it's a really good backup programme: I often use it to ensure copied folders are done correctly, and of course the Macs are cloned regularly. I have other backup/clone apps and tried more (Get Backup Pro 3, Forklift, SuperDuper!, etc.) but I always come back to CCC. Fully paid up user, no advert intended. And their support is good too.

*you initially said two PCs but using CCC would suggest you are just being very general and not saying what OS these PCs are running.

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