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Using NAS for Time Machine back ups

I used to have an Airport Time Capsule, which died a while ago. So I bought a G-Drive and connected it to my Linksys router (MX4200). It seemed to back up my iMac (M1) and Macbook (Intel) fine. However, recently, when I tried to restore some files Time Machine would only allow me to go back a few days and it refused to let me open the sparsebundle via the Network. Apple Support thought the external drive corrupted and advised to reformat it and do a new backup again. I am currently doing this and so far it seems fine. However, I wonder if there are any issues in my setup that could have caused the earlier problem?


I'm also a bit confused on the various file formats used. To get the Linksys to see my external storage I had to format it as Mac OS Extended (Journaled), although I understand that this is the format required for Time Machine to work anyway? However, I've also read that having a system running APFS means you can't then do a time machine restore from a different file format - ie. Mac OS Extended. Then again, in Disk Utility, it shows the backup, in the container volume, as being an APFS volume. Is this macOS's way around it?

iMac Line (2012 and Later)

Posted on Jan 18, 2022 9:09 AM

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Posted on Jan 18, 2022 11:23 AM

Thank you so much Barney for this reply. I bought the G-Drive as it was for sale in the Apple Store and the spec said 'Time Machine compatible'

That's when you connect it to the back of your Mac. You are connecting it to an unsupported router. The drive itself has nothing to do with the problems you are seeing.

Or to put it another way, what “Time Machine over SMB” NAS drive would you recommend?

Any drive will work with Time Machine, as long as it is connected to a supported "interface."

I don't know of any NAS that specifically states it supports that specification. They all will claim to allow you to backup to them using Time Machine, but they do that either through their hacked version of AFP or SMB--but they don't specify that their SMB implementation supports the specification. If you can determine which SMB file server they use, you can check the version to see if that version of the SMB server supports the spec. Most use Samba, so if they are running an unaltered version later than 4.8, it should support the spec. If their setup guide mentions any use of AFP, you should stay away from it. Apple never licensed AFP, so their AFP implementation is not true AFP, was never supported by Apple, and indicates they already play fast and loose with the facts.


I've always backed up over the network to a drive connected to a Mac Mini, previously a 2012 and now a 2020 M1. Never had issues with that setup, whether AFP or now SMB.

Hook up the drive to your iMac, partition it so you can backup both iMac to one partition and the MacBook to the other.

From the iMac Sharing System Preferences, share out the "network" partition and set it to be a Time Machine destination in File Sharing (ctrl-click on the drive and choose advanced options). If your user on the MacBook is the same as one on your iMac, you can use that to connect. Otherwise, create a Sharing Only user in Users & Groups and use those credentials. You'll have to give that user read/write on the shared partition.

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4 replies
Question marked as Top-ranking reply

Jan 18, 2022 11:23 AM in response to michael.amherst

Thank you so much Barney for this reply. I bought the G-Drive as it was for sale in the Apple Store and the spec said 'Time Machine compatible'

That's when you connect it to the back of your Mac. You are connecting it to an unsupported router. The drive itself has nothing to do with the problems you are seeing.

Or to put it another way, what “Time Machine over SMB” NAS drive would you recommend?

Any drive will work with Time Machine, as long as it is connected to a supported "interface."

I don't know of any NAS that specifically states it supports that specification. They all will claim to allow you to backup to them using Time Machine, but they do that either through their hacked version of AFP or SMB--but they don't specify that their SMB implementation supports the specification. If you can determine which SMB file server they use, you can check the version to see if that version of the SMB server supports the spec. Most use Samba, so if they are running an unaltered version later than 4.8, it should support the spec. If their setup guide mentions any use of AFP, you should stay away from it. Apple never licensed AFP, so their AFP implementation is not true AFP, was never supported by Apple, and indicates they already play fast and loose with the facts.


I've always backed up over the network to a drive connected to a Mac Mini, previously a 2012 and now a 2020 M1. Never had issues with that setup, whether AFP or now SMB.

Hook up the drive to your iMac, partition it so you can backup both iMac to one partition and the MacBook to the other.

From the iMac Sharing System Preferences, share out the "network" partition and set it to be a Time Machine destination in File Sharing (ctrl-click on the drive and choose advanced options). If your user on the MacBook is the same as one on your iMac, you can use that to connect. Otherwise, create a Sharing Only user in Users & Groups and use those credentials. You'll have to give that user read/write on the shared partition.

Jan 18, 2022 9:28 AM in response to michael.amherst

The source and destination do not have to be the same file system format. It doesn't restore the "file system," it restores the files.

A network storage device can be any format known. The file server that talks to the client machines does the writing to disk, not Time Machine.

Network backups are written to a Sparse Bundle Disk Image "file." It will be formatted however Time Machine wants it to be formatted. On a directly connected drive, Time Machine uses APFS (case-sensitive) since Big Sur. It is an entirely different backup scheme than the old HFS+ concept. The sparse bundle disk image will be formatted APFS and could exist on just about any file system.


The problems with backing up to a NAS or your "NAS-like" setup is the file server isn't capable of doing the necessary error-checking required of a Time Machine backup. Apple published a specification for backing up over SMB that the NAS must support in order to have reliable backups. Those checks were built into AFP, but not into the Netatalk hack that NAS devices used to simulate AFP. Whatever the MX4200 uses to file share over SMB must support the "Time Machine over SMB" specification.

If it uses Samba, then it would need version 4.8 or later. If it doesn't use Samba, it would need to specify that it has incorporated the "Time Machine over SMB" specification in its SMB implementation.

Jan 18, 2022 9:45 AM in response to Barney-15E

Thank you so much Barney for this reply. I bought the G-Drive as it was for sale in the Apple Store and the spec said 'Time Machine compatible' so I assumed it would work as it should. From what you say though is the issue not with the G-Drive but the MX4200? Anyway I can check how it uses SMB and whether it does support Time Machine over SMB? Essentially, is my setup issue the router I use rather than the NAS storage?

Using NAS for Time Machine back ups

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