Time Machine couldn’t complete the backup to “DiskStation.local” (synology ds231+)

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Mitch Leung Author

Level 1

85 points

Time Machine couldn’t complete the backup to “DiskStation.local” (synology ds231+)

The backup disk is not available. Make sure the backup disk is connected or select a different backup disk.

I've been backup to the NAS for years. Currently on

Big Sur 11.7.1 &

DSM 6.2.4-25556 Update 6 on NAS

Until late October 2022, it fails with the above message. I did verified that I am following synology's kb all along

Tried AFP only, SMB only, AFP & SMB enabled. Changed network cable. No good.

However I can mount the NAS shared folder and copy to and from it without issues.

From macos console

default 10:12:13.284113+1300 backupd GetNetAuthAuthAgentPort: Calling bootstrap_look_up3() for com.apple.netauth.user.auth; uid = 0, euid = 0

default 10:12:13.284519+1300 backupd Calling bootstrap_look_up3() for com.apple.netauth.sys.auth

default 10:12:13.284830+1300 backupd GetNetAuthAuthAgentPort: gNetAuthAuthAgentPort = 14915

default 10:12:16.002693+1300 backupd Connecting to hdiejectd

default 10:12:16.013964+1300 backupd Connected successfully

default 10:12:47.270067+1300 backupd Connecting to hdiejectd

default 10:12:47.271300+1300 backupd Connected successfully

error 10:13:12.956345+1300 backupd-helper Invalid mountpoint '/Volumes/Backups of MBP' - failed to open '/Volumes/Backups of MBP/.iotest', error: 5 Input/output error

error 10:13:13.277782+1300 backupd Invalid mountpoint '/Volumes/Backups of MBP' - failed to open '/Volumes/Backups of MBP/.iotest', error: 5 Input/output error

error 10:13:13.677990+1300 backupd Invalid mountpoint '/Volumes/Backups of MBP' - failed to open '/Volumes/Backups of MBP/.iotest', error: 5 Input/output error

error 10:13:13.880742+1300 backupd Backup failed (19: BACKUP_FAILED_TARGETVOL_NOT_MOUNTED - The backup disk could not be resolved, or there was a problem mounting it.)

error 10:13:14.117310+1300 backupd Diskmanagement failed to unmount disk '/Volumes/Backups of MBP', error: {

Action = Unmount;

Dissenter = 1;

DissenterPID = 0;

DissenterStatus = 49168;

Target = "file:///Volumes/Backups%20of%20MBP/";

}

error 10:13:14.389942+1300 backupd Diskmanagement failed to unmount disk '/Volumes/.timemachine/DiskStation._smb._tcp.local./B2B1C85B-A80A-42D7-8AD5-0634C2F8BA8D/NetDrive', error: {

Action = Unmount;

Dissenter = 1;

DissenterPID = 17893;

DissenterPPID = 1;

DissenterStatus = 49168;

Target = "file:///Volumes/.timemachine/DiskStation._smb._tcp.local./B2B1C85B-A80A-42D7-8AD5-0634C2F8BA8D/NetDrive/";

}

error 10:13:14.393515+1300 backupd Failed to unmount '/Volumes/.timemachine/DiskStation._smb._tcp.local./B2B1C85B-A80A-42D7-8AD5-0634C2F8BA8D/NetDrive', error: Error Domain=com.apple.diskmanagement Code=0 "No error" UserInfo={NSDebugDescription=No error, NSLocalizedDescription=No Error.}

Any ideas on whether it's software settings or hardware issues? All my 3 Macs are unable to backup to NAS. All used to be able to backup via Time Machine and they are all on 11.7.1

Cheers,

Mitch

MacBook Pro

Posted on Nov 14, 2022 1:32 PM

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Answer 1

Top-ranking reply

Mitch Leung Author

Level 1

85 points

Nov 26, 2022 8:38 PM in response to kamote0628

FYI, it happens to ALL Macs with Big Sur 11.7.1

I have a backup system of Big Sur with 11.7.0 and still not working when backing up to NAS.

My conclusion is the SMB backup to NAS is broken by 11.7 update since.

After much testing and support from Synology, turns out Big Sur when backup is asking as READ ONLY permission and then it tries to write and fail of coz. Hence the not working part.

Here's what the Synology support found with all the logs collected:

After checking with the developers, we found that the mac client opens a file with Read Only (RO) mode when processing the TimeMachine backup.

Therefore, it is an expected behavior that the server (NAS) replies an Access Denied regarding the abnormal behavior:

Therefore, we suspect the issue is caused by the client (mac) itself rather than the server (NAS).

I've also tested with sharing a USB drive as shared Time Machine backup drive from 1 mac (on 11.7.1) to another mac (on 11.7.1), and fails the same way with NAS.

Then today I upgraded 1 mac directly from 11.7.1 to Ventura 13.0.1 on a separate drive. Time Machine seems to be working thou still in progress as writing this message.

However for stability of work. I need to go back to my Big Sur partition.

but Apple should fix this SMB read only issue with SMB NAS issue with Time Machine.

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Answer 2

Nov 16, 2022 10:22 AM in response to Mitch Leung

Hello Mitch Leung

To help resolve the issue with the "Time Machine backup can't be found" error, try following the steps from this article: Time Machine troubleshooting on Mac - Apple Support

The backup disk is unavailable or can’t be found or “mounted”

If Time Machine on your Mac can’t find your backup disk

If you need a password to unlock your backup disk on Mac

Best Regards.

Reply

Answer 3

kamote0628

Community Specialist

Nov 16, 2022 4:43 PM in response to Mitch Leung

Hi Mitch Leung, Thank you for keeping us posted.

Do you happen to have a different external drive that you can use to further isolate the issue?

If yes, would you please try to secure a Time Machine backup on a different external drive.

If no, let’s check if the issue persists when signed in on a different user account.

Performing this step can also help in isolating the issue.

The article below can help if you do not have any other user account to test with.

Set up users, guests, and groups on Mac

If you are experiencing the issue when signed in on a different user account, please check if the issue persists while on safe mode.

Safe mode does a basic check of your startup disk, similar to using First Aid in Disk Utility.

Performing this step may help resolve the issue, or further isolate the issue.

Below is an article to help guide you through the process.

How to use safe mode on your Mac

Take care!

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Answer 4

mario49

Community Specialist

Nov 27, 2022 11:08 AM in response to Mitch Leung

Hey Mitch Leung,

Thanks again for getting back to us.

If you're still having issues with Big Sur and using Time Machine with the NAS, contact Apple Support. From there, they can look further into this with you: Contact - Official Apple Support

Cheers!

Reply

Answer 5

Mitch Leung Author

Level 1

85 points

Nov 16, 2022 4:34 PM in response to Community User

I've already tried everything and the Apple's trouble shooting page isn't helping.

The issue I'm having is I can copy to/from the NAS via SMB or AFP

Backup to attached USB drives is working fine as well.

But TimeMachine backup always die with

"Runtime corruption check not completed - the backup disk could not be found" no matter it's an previous backup or a new backup.

Time Machine couldn’t complete the backup to “DiskStation.local” (synology ds231+)

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