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after copying a big amount of data from one 3tb disk (Mother) to another (Backup) overnight i put my computer out. After i put it on again it took about 30 min for "Mother" to reappear with the message that "Backup" (which isn't connected) is damaged and read only and needs to be backed up and reformatted etc.

All the data seems to be there but there are a couple of files in the main directory that were in subfolders before.

The curious thing is in the finder i see "Mother" but in the Disk Utility it shows me "Backup". If the real "Backup" is connected too, he renames the false "Backup" to "Backup-1" and displays it normal. If the real "Backup" isn't connected Disk Utility displays the false "Backup" greyed out and the log tells me there are 2 partitions (it's only 1 in reality). Either way i cannot rename it back to "Mother". When i use Terminal "diskutil list" i get this:

/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *750.2 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:          Apple_CoreStorage                         544.3 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
   4:       Microsoft Basic Data BOOTCAMP                205.0 GB   disk0s4
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS OS                     *543.9 GB   disk1
                                 Logical Volume on disk0s2
                                 14FA1A65-BDAD-4265-97D7-C490A82497F4
                                 Unencrypted
/dev/disk2
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *3.0 TB     disk2
   1:                        EFI EFI                     209.7 MB   disk2s1
   2:                  Apple_HFS Backup                  3.0 TB     disk2s2
/dev/disk3
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *3.0 TB     disk3
   1:                        EFI EFI                     209.7 MB   disk3s1
   2:                  Apple_HFS Backup                  3.0 TB     disk3s2
user:~ user$ 

While Disk Utility gives me this when i try verifying the disk

  • extents overflow file.Checking catalog file.Invalid extent entryMissing thread record (id = 677462)Missing thread record (id = 677464)Missing thread record (id = 1868689)Missing thread record (id = 1868893)Missing thread record (id = 1871148)Missing thread record (id = 2251985)Incorrect number of thread recordsIncorrect number of thread recordsChecking multi-linked files.Checking catalog
    hierarchy.Invalid volume directory count(It should be 50366 instead of 50276)Invalid volume file count(It should be 975759 instead of 973989)Checking extended attributes file.Invalid map nodeChecking volume bitmap.Volume bitmap needs minor repair for orphaned blocksChecking volume information.Invalid volume free block count(It should be 69452625 instead of 69452562)The volume Mother was found corrupt and needs to be repaired.File system check exit code is 8.Error: This disk needs to be repaired. Click Repair Disk.

i guess these Missing Threads are the files he accidentally threw in the main directory...

i found the UUID nrs through Terminal "diskutil info". They are different... i tried yesterday renaming the damaged volume through terminal. i got an error. here s what terminal found about the disks

user:~ user$ diskutil info Backup Device Identifier: disk2s2 Device Node: /dev/disk2s2 Part of Whole:
disk2 Device / Media Name: Mother

Volume Name: Backup

Mounted: Yes Mount Point:
/Volumes/Backup

File System Personality: HFS+ Type (Bundle): hfs
Name (User Visible): Mac OS Extended Owners:
Disabled

Partition Type: Apple_HFS OS Can Be Installed: No Media Type: Generic Protocol: USB
SMART Status: Not Supported Volume UUID:
36B16976-E7D9-3C46-A3EA-F1206F550B65 Disk / Partition UUID:
034A8B08-FE44-4A62-9D43-9828C50D4F77

Total Size: 3.0 TB (3000249008128 Bytes) (exactly 5859861344 512-Byte-Units) Volume Free Space: 569.0 GB (568955387904 Bytes) (exactly 1111240992 512-Byte-Units) Device Block Size: 512 Bytes Allocation Block Size: 8192 Bytes

Read-Only Media: No Read-Only Volume: Yes
Ejectable: Yes

Whole: No Internal: No

user:~ user$ diskutil info Mother Could not find disk: Mother user:~ user$ diskutil info Backup Device Identifier: disk3s2
Device Node: /dev/disk3s2 Part of Whole:
disk3 Device / Media Name: Backup

Volume Name: Backup

Mounted: Yes Mount Point:
/Volumes/Backup 1

File System Personality: Journaled HFS+ Type (Bundle):
hfs Name (User Visible): Mac OS Extended (Journaled)
Journal: Journal size 229376 KB at offset 0x5754000
Owners: Disabled

Partition Type: Apple_HFS OS Can Be Installed:
Yes Media Type: Generic Protocol:
USB SMART Status: Not Supported Volume UUID:
49D8B7AD-6F33-3741-BBBA-47C2D97E4B99 Disk / Partition UUID:
D2845830-56AD-46ED-B99B-5331413CDE4E

Total Size: 3.0 TB (3000249008128 Bytes) (exactly 5859861344 512-Byte-Units) Volume Free Space: 1.4 TB (1363579531264 Bytes) (exactly 2663241272 512-Byte-Units) Device Block Size: 512 Bytes Allocation Block Size: 4096 Bytes

Read-Only Media: No Read-Only Volume: No
Ejectable: Yes

Whole: No Internal: No

user:~ user$ diskutil info Mother Could not find disk: Mother user:~ user$

any help is greatly appreciated!

have a nice sunday

thanks in advance

P.S: i'm on an early 2011 15" Macbook Pro using Yosemite

  • A wild guess: Your two disks may have identical GUID (disk or partition serial number) or UUID (filesystem serial number) values, which could be confusing Disk Utility and/or OS X. You can check the GUID values with some disk partitioning tools. For instance, my gdisk shows the disk's GUID when you launch it on a disk, and shows partition GUIDs when you select the i option to show detailed information on a partition. I'm not sure offhand what OS X tools show filesystem UUIDs, but blkid in Linux will do so. – Rod Smith Nov 22 '15 at 16:12
  • mmmh could be even though i thought these numbers should be so unique. On the other hand i' using these 2 disks all the time, so its weird that the problem occurs just now. Is there a way to make my computer understand that he's just looking for the wrong name? i tried renaming through terminal but got an error. Thanks Rod! – Hans Holzer Nov 22 '15 at 16:51
  • The GUID and/or UUID numbers might be duplicated if one disk was created by cloning another, depending on the software used. I recommend checking this detail. If it's the cause of the problem, then the solution is to set new GUID or UUID values on the affected disk, partition(s), or filesystem(s). – Rod Smith Nov 22 '15 at 18:39
  • ooh i see, but actually i just copied a folder containing 350 gb of music, not the entire disk, can that still happen, then? thanks again! – Hans Holzer Nov 22 '15 at 18:42
  • From your description, it shouldn't have. It's worth checking my hypothesis, simply because it's the only explanation I can think of. – Rod Smith Nov 22 '15 at 18:45

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