/dev/sda*，无法 mount

命令执行和返回结果如下：

# mount /dev/sda7 /mnt
-> mount: /dev/sda7 is write-protected, mounting read-only
-> mount: cannot mount /dev/sda7 read-only

# mount -o remount /dev/sda7 /mnt
-> mount: cannot mount /dev/sda7 read-write, is write-protected

# mount -o ro /dev/sda7 /mnt
-> mount: cannot mount /dev/sda7 read-only

(sda7 为未挂载设备，sda*同 sda7，修改 /etc/fstab 可正常挂载)

如何检查？