Mounting file system, fstab, mtab

Basic format: mount -t <filesystem type> old_dir new_dir

1> Mounting a directory to another directory to let them access the same content
mount --bind old_dir<directory has content> new_dir<directory designed to access the content>

2> Mounting a device <like CDROM> with no -t parameter, it will let the OS to guess
mount /dev/cdrom /cd

3> NFS

• /etc/exports specifies the access control of the mounting directory.

/home vale(rw) vstout(rw) vlight(rw)
/usr/X11R6 vale(ro) vstout(ro) vlight(ro)
/usr/TeX vale(ro) vstout(ro) vlight(ro)
/ vale(rw,no_root_squash)
/home/ftp (ro) 

/var/myApp 172.16.95.17/255.255.255.255(rw,no_root_squash) 

Each line defines a directory and the hosts allowed to mount it. Wildcard is allowed (* ?).

Range of ip address / network mask can be used to specify the host. 

If no host is give, any host matches and is allowed to mount the directory.

• CLI form to mount NFS volume. 

  mount -t nfs nfs_volume local_dir options

• /etc/fstab entry of NFS

[root@localhost ~]# cat /etc/fstab
/dev/VolGroup00/LogVol00 /                       ext3    defaults        1 1
/dev/VolGroup00/LogVol01 /data                   ext3    defaults        1 2
LABEL=/boot1            /boot                   ext3    defaults        1 2
tmpfs                   /dev/shm                tmpfs   defaults        0 0
devpts                  /dev/pts                devpts  gid=5,mode=620  0 0
sysfs                   /sys                    sysfs   defaults        0 0
proc                    /proc                   proc    defaults        0 0
LABEL=SWAP-sda6         swap                    swap    defaults        0 0
172.16.95.93:/var/myApp    /logserver-1/var/myApp     nfs     hard,intr       0 0

4> fstab and mtab
[root@localhost ~]# cat /etc/fstab
/dev/VolGroup00/LogVol00 /                       ext3    defaults        1 1
LABEL=/boot             /boot                   ext3    defaults        1 2
tmpfs                   /dev/shm                tmpfs   defaults        0 0
devpts                  /dev/pts                devpts  gid=5,mode=620  0 0
sysfs                   /sys                    sysfs   defaults        0 0
proc                    /proc                   proc    defaults        0 0
/dev/VolGroup00/LogVol01 swap                    swap    defaults        0 0
/var/myApp /localserver-1/var/myApp none rw,bind 0 0

There are 3 ways of using fstab.
1> mount -a will cause all the filesystem listed on fstab to be mounted, except those noted as noauto. Adding the -F will make mount fork. Usually it is used by boot scripts.

2> To mount or umount the filesystem mentioned on the fstab, it is sufficed to give only the device or the mount point.

e.g In fstab, /tmp/a /tmp/b none rw,bind 0 0
mount /tmp/a or mount /tmp/b will suffice.

3>  Normally, only the superuser can mount  file  systems.   However, when  fstab  contains  the user option on a line, anybody can mount the corresponding system.