Mac M1 8TB backup to Synology NAS

Re: MacBook Pro
Apple M1 max (chip)
running macOS Sanoma 14.5
with 8TB SSD

[Time of Occurrence]
I was successfully backing-up, using time machine to my NAS for a number of years. However this all changed when I upgraded to my new laptop (see above) and yes I’ve been slack as I’ve not had successful backup of my mac since then which is a few years ago now.

[Steps taken to resolve the issue]
*First I phoned Apple Help who confirmed that the setup for Time Machine was correct but because I was backing up to a Synology NAS their help was limited as they have zero training in NAS.
*Two or three times I’ve started from scratch and setup time machine to backup to my NAS. It always appears to be working initially but then gives the same error message (see screenshot attached). All my attempts have so far been unsuccessful which is why I’m turning to you for advice …thank you.

[Where I’m now at with TimeMachine]
I’m beginning to think that my Mac with its 8TB SSD is more than Time Machine can handle …maybe the backup takes so long (via wi-fi) that it times out but that’s just my thinking. I’d love to continue with Time Machine but maybe it’s time I used a backup solution in the Synology pack. Which raises the question …which one is best suited for me and my hardware. Can you please recommend one to me?

Kind regards,

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I’ve heard good things about Arq.


My long time experience with TimeMachine is that it is unreliable unless the backup is an external drive that is connected directly (no server!).

I’ve had excellent results with Chronosync to backup to a server. It should also work fine with a NAS. ChronoSync | The Ultimate Mac Backup and File Sync App



I’ve been using Arq for offsite backups since 2012


And ChronoSync for local backups since 2007 (or longer)


You don’t say how much free space available on the NAS, or how much of the 8TB (that’s a lot!) is actually used.

As a first step I would review the setup in the NAS for accepting TimeMachine backups. See

I use separate ID for Timemachine (one for each of my three Macs) to backup to Synology NAS, and I give them a quota of double the disk space on the Mac. I’m wondering if your quota (if set) is too small. That would be 16 TB (which is a lot).

Also in TimeMachine exclude folders that you really do not need or want to be back-ed up.

I doubt it’s that TimeMachine can’t handle 8TB. I suspect the target destination, and that it will take a long time to process all that data, especially the initial backup. With all those TB’s, days to complete? Any backup software will take the time it takes.

That being said, while I use TimeMachine as the primary backup, and it’s very useful for restoring files from my blunders (accidental file deletes, changes, wanting to go back to, etc.), I also use Carbon Capture Cloner to backup really important stuff (to NAS), TimeMachine (redundantly) to an attached USB, and Backblaze. I also recommend Chronosync, but I’m not currently using it for backup. Also experimenting with Dropbox’s new backup (not sync) service which seems to be ok. I backup the NAS important folders to that Dropbox backup service.

Edit: Nagging in the back of my mind is that reuse of a Time Machine backup store does not work with a different machine. Probably some sort of unique machine-code (if my memory correct…did not research further). If true, might be why your NAS backups failed with new machine if not re-set.


I also have had problems with Time Machine backups to a network share.

My solution was to buy a portable 8 TB USB drive and make Time Machine backups of my Macbook’s 4 TB internal ssd to that. I haven’t had a problem since.

If you read up on local vs remote( network) Time Machine backups, you’ll discover that they work differently. That may explain why local ™ backups are more reliable.

I use Backblaze for offsite backups.


You might want to consider using the Synology Active Backup solution:

As others have said, Time Machine over the network has never been all that reliable for me. Switching to a directly attached SSD, on the other hand, has been 100%.

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I use both TimeMachine to NAS on Synology and to attached USB spinning drive and a SSD for laptop, and both network and local TimeMachine backups working fine for years. I know they work as I do test restores periodically.

I had the same problem before my Synology failed. (CPU overheating issue - not impressed).

I switched to ChronoSync before it failed.