For now; hope you are all healthy !?
To my question:
1) Who knows this message (hard disk utility first aid) - Warning: MT mapping is not completely referenced?
Now had no (or only the usual Catalina) problems, but occasionally run first aid over it.
This message comes at "Container disc2" at the end of the check. The same when checking from "Fusion Drive". The same message comes.
With Macintosh HD 1 + 2 data - does this message not appear?
Couldn't find much about it on the net, tried some suggestions https://discussions.apple.com/thread/251159425 but didn't do anything. Ne reinstall. I still did before I don't know what that means - I have backups with TM anyway. That with the reinstall. was a recommendation to fix the problem - whatever the consequences could be ....?
2) Did someone check that with "first aid"?
3) If so. Does this message come from Erste H. only for "Container disc2" and "Fusion Drive"?
I found that after Catalina installation. Clean installation didn't help either?
I was unfortunately not able to load a ScreenShot ??
Run first aid on "Container disk2"
The computer does not respond while the startup disk is being checked.
Check storage system
Use live mode.
Execute fsckapfs -n -x -l / dev / disk0s2
Checking the container superblock.
Checking the fusion superblock.
Checking the EFI jumpstart record.
Checking the space manager.
Checking the space manager free queue trees.
Checking the object map.
Checking the Fusion data structures.
Checking volume.
Checking the APFS volume superblock.
The volume Macintosh HD - Data was formatted by diskmanagementd (1412.141.1) and last modified by apfskext (1412.141.1).
Checking the object map.
Checking the snapshot metadata tree.
Checking the snapshot metadata.
Checking snapshot 1 of 2 (com.apple.TimeMachine.2020-07-29-150921.local)
Checking snapshot 2 of 2 (com.apple.TimeMachine.2020-07-29-170616.local)
Checking the extent ref tree.
Checking the fsroot tree.
Checking volume.
Checking the APFS volume superblock.
The volume Preboot was formatted by diskmanagementd (1412.141.1) and last modified by apfskext (1412.141.1).
Checking the object map.
Checking the snapshot metadata tree.
Checking the snapshot metadata.
Checking the extent ref tree.
Checking the fsroot tree.
Checking volume.
Checking the APFS volume superblock.
The volume recovery was formatted by diskmanagementd (1412.141.1) and last modified by apfskext (1412.141.1).
Checking the object map.
Checking the snapshot metadata tree.
Checking the snapshot metadata.
Checking the extent ref tree.
Checking the fsroot tree.
Checking volume.
Checking the APFS volume superblock.
The volume VM was formatted by diskmanagementd (1412.141.1) and last modified by apfskext (1412.141.1).
Checking the object map.
Checking the snapshot metadata tree.
Checking the snapshot metadata.
Checking the extent ref tree.
Checking the fsroot tree.
Checking volume.
Checking the APFS volume superblock.
The volume Macintosh HD was formatted by diskmanagementd (1412.141.1) and last modified by apfskext (1412.141.1).
Checking the object map.
Checking the snapshot metadata tree.
Checking the snapshot metadata.
Checking snapshot 1 of 2 (com.apple.TimeMachine.2020-07-29-150921.local)
Checking snapshot 2 of 2 (com.apple.TimeMachine.2020-07-29-170616.local)
Checking the extent ref tree.
Checking the fsroot tree.
Verifying allocated space.
warning: MT mapping (0x4000004048a40 -> 0x12ceb94, 164, C) is not completely referenced
warning: MT mapping (0x4000004048bb8 -> 0x12cecfa, 344, C) is not completely referenced
warning: MT mapping (0x4000004048dff -> 0x12cef11, 106, C) is not completely referenced
warning: MT mapping (0x40000040dd7fd -> 0x1354f87, 32, C) is not completely referenced
warning: MT mapping (0x40000040f24b7 -> 0xa5ef4d, 1, C) is not completely referenced
warning: MT mapping (0x40000040f8294 -> 0x850e9a, 2, C) is not completely referenced
warning: MT mapping (0x40000040fff30 -> 0x137268b, 164, C) is not completely referenced
warning: MT mapping (0x40000041000a8 -> 0x13727f1, 190, C) is not completely referenced
warning: MT mapping (0x40000041075f7 -> 0xa5ebe9, 1, C) is not completely referenced
warning: MT mapping (0x400000410760b -> 0x1377f47, 8, C) is not completely referenced
warning: MT mapping (0x400000410761c -> 0xa5ebf1, 1, C) is not completely referenced
warning: MT mapping (0x400000410761d -> 0x1377f57, 8, C) is not completely referenced
warning: MT mapping (0x4000004107625 -> 0xa5ebfe, 1, C) is not completely referenced
warning: MT mapping (0x4000004107626 -> 0x1377f5f, 8, C) is not completely referenced
warning: MT mapping (0x4000004107aec -> 0x13782f6, 24, C) is not completely referenced
warning: MT mapping (0x4000004107b05 -> 0x137830e, 32, C) is not completely referenced
warning: MT mapping (0x4000004107b26 -> 0x137832e, 24, C) is not completely referenced
warning: MT mapping (0x4000004107b3f -> 0x1378346, 32, C) is not completely referenced
warning: MT mapping (0x400000410a877 -> 0xd296fd, 6, C) is not completely referenced
The volume / dev / disk0s2 appears to be OK.
Storage system check exit code is 0.
Operation successful.
what is to blame for the mistake?