UNIX for Advanced & Expert Users

While I was reading a Sun SysAdmin Guide, I came across this point...

/etc/vfstab Field Descriptions
mount at boot -

The root (/), /usr and /var file systems are not mounted from the vfstab file initially.
This field should always be set to no for these file systems and for virtual file systems such as /proc and /dev/fd.

My question is if root (/) etc.. are not mounted from vfstab.. then what is the process at startup.??

Also any reasons why it is set as NO..

Any views would be highly appreciated.

i think that /proc is not on the drive, it is in ram, hence vfstab, "virtual"
everything on harddrive, floppy, cdrom mount points are defined in /etc/fstab .
for syntax see the command,
man mount

Hi,

The root (/ ) and the usr ( /usr ) file systems are mounted during the boot process as read only as part of the kernel modules.

But as the boot process proceeds, these are remounted as part of the rcS.d scripts ( S40standardmounts.sh ).

But the other entries in vfstab are mounted as part of rc2.d scripts ( S01MOUNTFSYS) using *mountall -l* command. This command mounts all local file systems with *mount at boot = yes * option.

you can also have a look at man pages of mountall, vfstab and mount for more info.

Thanks