是什么原因造成的？
在启动菜单中我收到以下警告：
Disk /dev/sdb - 12 GB / 11 GiB - CHS 1502 255 63
Partition Start End Size in sectors
P FAT32 0 0 1 1502 63 33 24133632 [NO NAME]
Boot sector
check_FAT: Unusual media descriptor (0xf0!=0xf8)
Warning: number of heads/cylinder mismatches 4 (FAT) != 255 (HD)
Warning: number of sectors per track mismatches 16 (FAT) != 63 (HD)
OK
Backup boot sector
check_FAT: Unusual media descriptor (0xf0!=0xf8)
Warning: number of heads/cylinder mismatches 4 (FAT) != 255 (HD)
Warning: number of sectors per track mismatches 16 (FAT) != 63 (HD)
OK
Sectors are identical.
A valid FAT Boot sector must be present in order to access
any data; even if the partition is not bootable.
选择重建 BS（引导扇区）后，我收到警告：
Disk /dev/sdb - 12 GB / 11 GiB - CHS 1502 255 63
Partition Start End Size in sectors
P FAT32 0 0 1 1502 63 33 24133632 [NO NAME]
FAT : 32
cluster_size 64 64
reserved 32 32
total_sect 24133632 24133632
fat32_length 2946 2946
root_cluster 2 2
free_count uninitialised 375052
next_free uninitialised 514
Extrapolated boot sector and current boot sector are different.
修复引导扇区完成后没有任何变化：我仍然可以复制与以前相同数量的文件
如何修复此问题？（非常重要的文件） 也许我应该使用“修复 FAT 非常危险！仅限专家！”选项？