My external hard drive (seagate barracuda with good SMART status insidev erbatim 4TB store 'n' go) has 3 main partitions:

1) ntfs
2) hfs+ for time machine backup
3) exfat to transfer files between windows and mac

Windows shows correctly all partitions without errors or warnings. Mac shows only 1 and 2. The third is occupied by fsck_exfat which started automatically every time I plug the hard drive in. So I force close that process, go to terminal, digit "sudo fasck_exfat -d disk1s2" and press enter. After a while it shows:

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.
** Rechecking alternate boot region.
Mark volume clean?

Type yes but then:

fsck_exfat: Could not update main boot region: Bad file descriptor.

After that the disk is now visible in finder in ready only mode. I have already formatted 2 times this partition but the result is the same.

  • same problem with WD Element, exFAT on whole partition of a 4TB HDD. maybe mac does not handle exFAT that well.. Did you solve the problem ? My OS : 1.9.5 . Tried "sudo fsck_exfat -y disk1s2" multiple times (grant yes to solve problems), same results. "fsck_exfat -q disk1s2" report FILE SYSTEM DIRTY, but that HDD is able to be read and written. – user305883 Mar 24 '19 at 8:42

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