/etc/fstab尾巴的两个数字有不同用途.
第一个专门给dump命令,0表示不要dump.
第二个数字用来控制系统启动时的文件系统检查.
0表示不要检查(如/proc, cdrom, floppy等).
1表示第一轮检查,只有/才用
2表示第二轮检查,用于/usr, /var, /home等.
man fstab相关段落:
The fifth field, (fs_freq), is used for these filesystems by the dump(8) command to determine which
filesystems need to be dumped. If the fifth field is not present, a value of zero is returned and
dump will assume that the filesystem does not need to be dumped.
The sixth field, (fs_passno), is used by the fsck(8) program to determine the order in which filesys
tem checks are done at reboot time. The root filesystem should be specified with a fs_passno of 1,
and other filesystems should have a fs_passno of 2. Filesystems within a drive will be checked
sequentially, but filesystems on different drives will be checked at the same time to utilize paral
lelism available in the hardware. If the sixth field is not present or zero, a value of zero is
returned and fsck will assume that the filesystem does not need to be checked.