difference between filesystem and mountpoint

[Zinky · Accepted solution]

Matti's explanation is utmost correct. I use the same explanation in my crusade against proper technical terminologies and jargons in my site.


Filesystems are data structure or format that exist on top of addressable block or raw or even file devices. Among the most well known filesystems are the ext family on Linux, ufs on BSD and Solaris, vxfs from Veritas/Symantec for all platforms. There are many others in various forms of development.

Now in case you have heard of ZFS (w/c is stable and coming to Linux) and claim it to be a "filesystem" that needs a mount point -- he/she is half correct -- but I digress.

Filesystems need to be mapped or mounted to a directory (also called a mount point). A mount point need not be a top level directory.

Filesystems can be created and exist on top of:
1) a whole simple disk
/dev/sdb on /apache/logs type vxfs (rw)

2) a disk partition
/dev/sdc3 on /saplog type ext4 (rw)

3) an LVM logical volume
/dev/mapper/sapvg01-logvol01 on /saplog01 type vxfs (rw)

4) a VxVM volume
/dev/rdsk/sapdg02/data01 on /sapdata01 type ext3 (rw)

5) a multipathed disk
/dev/mapper/SAPDISK01 on /sapdata type vxfs (rw)

6) a raid device
/dev/cciss/c0d1p1 on /apache type ext3 (rw)

7) a prorietary device say from EMC (Powerpath) or IBM (SVC)
... don;t have it..

8) a loopback file device
/data/file.dsk on /mnt/c type ext3 (rw,loop=/dev/loop2)


So "mount point" and "filesystem" cannot be used interchangeably IMHO. The precise way of using and commnicating is:

say you have:

# df -k /apache/logs

Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vgapache-logs 1Tb .5Tb .5Tb 50% /apache/logs

# mount |grep logs
/dev/mapper/vgapache-logs on /apache/logs type ext3 (rw)

You would communicate it this way and it will impress your boss (assuming he is technical):

The mount point /apache/logs is an ext3 filesystem that resides on a logical volume named logs that is carved out of an LVM Volume Group vg-apache. It has 50% occupancy.



Hope this helps.

[bullz]

@ Alzhy
Really itâ s time to say wowâ ¦

@ Steven Schweda
Got so much info.

Thanx all.

[bullz]

Thanx