First of all Thank You very much for replying and helping me with this problem.
This is what I get as a response from the instructions you gave me:
“fsck_exfat: Cannot write main boot region: Bad file descriptor
** The volume ADELANTO 2 could not be verified completely.”
Here is what I did to get the above response:
I ran the terminal commands as directed. Here is what I got . . .
I ran “diskutil list” first and got this:
/dev/disk3 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *6.0 TB disk3
1: EFI EFI 209.7 MB disk3s1
2: Microsoft Basic Data 6.0 TB disk3s2
Then I ran the command you gave me as follows: “sudo fsck_exfat -d disk3s2”
This is the response though I’m only listing the first few lines as the rest is quite long and it looks like file and directory names mostly.
“Shannons-iMac:~ shannonnoble$ sudo fsck_exfat -d disk3s2
fsck_exfat: Opened /dev/rdisk3s2 read-only
** Checking volume.
** Checking main boot region.
fsck_exfat: Invalid boot region checksum
Main boot region is invalid. Trying alternate boot region.
** Checking alternate boot region.
11720373344 total sectors; 512 bytes per sector
FAT starts at sector 32768; size 196608 sectors
22890906 clusters starting at sector 229376; 262144 bytes per cluster
Root directory starts at cluster 14
Read offset = 0x000001000000 length = 0x001000
** Checking system files.
Read offset = 0x000007300000 length = 0x040000
** Volume name is ADELANTO 2.
Found active bitmap; first cluster 2, length 2861364
** Checking upper case translation table.
Read offset = 0x0000072c0000 length = 0x040000
Found upcase table; starting cluster 13, length 5836
** Checking file system hierarchy.”
At the end of the list of files and directories I finally get this:
"** Checking active bitmap.
Checking bitmap cluster 2
Read offset = 0x000007000000 length = 0x040000
Checking bitmap cluster 3
Read offset = 0x000007040000 length = 0x040000
Checking bitmap cluster 4
Read offset = 0x000007080000 length = 0x040000
Checking bitmap cluster 5
Read offset = 0x0000070c0000 length = 0x040000
Checking bitmap cluster 6
Read offset = 0x000007100000 length = 0x040000
Checking bitmap cluster 7
Read offset = 0x000007140000 length = 0x040000
Checking bitmap cluster 8
Read offset = 0x000007180000 length = 0x040000
Checking bitmap cluster 9
Read offset = 0x0000071c0000 length = 0x040000
Checking bitmap cluster 10
Read offset = 0x000007200000 length = 0x040000
Checking bitmap cluster 11
Read offset = 0x000007240000 length = 0x040000
Checking bitmap cluster 12
Read offset = 0x000007280000 length = 0x040000
0 clusters were marked used, but not referenced
0 clusters were marked used and CLUST_BAD
0 clusters were marked free, but referenced
** Rechecking main boot region.
Main boot region needs to be updated.
fsck_exfat: Cannot write main boot region: Bad file descriptor
** The volume ADELANTO 2 could not be verified completely.
Shannons-iMac:~ shannonnoble$ "
Like I said. I checked these drives on 3 Macs running 10.11.6 and one PC. Client says they are using the same operating system on Macs.
Thank you again for your help!