why we need to mount file system other than / file system

UNIX Solaris
1

Hi,

I am new to solaris OS.I have a small question,it might be silly question or good question.

My Question is

Solaris is following hierarchy type of file structure,means all files are under the root file system.so Once we mount the root file system all sub folders of / ( /usr, /var , /etc) are automatically mounted . Than what is the purpose of mounting /usr,/var,/etc .... file systems separtly. please let me know whether point of view is correct or not?

Thanks
Maro

2

there are several reasons to put files in different mount points. for example:
/var is the directory where "logfiles" will go to. if / and /var are on the same filesystem and logfiles are growing, the / filesystem can run out of space. on most unix/linux system this will/can crash the mashine...

3

Hi DukeNuke2,

I think you misunderstood my question. My question is if we mount a / file system , all the the other file systems like /etc , /var , /usr will automatically mounted or not because these are all (/usr,/var,/tmp) sub folders of the root file system.

Am i Correct ? I knew that / , /usr , /var file system are in different cylinders of the disk. But how they comes under the / file system. Whether / is the folder or a file system?

Thanks
Maro

4

they are mounted cause they are (or better they should be) in "/etc/fstab" or "/etc/vfstab" depending on your os.

5

Hi DukeNuke2,

I knew that its booting based on /etc/fstab file. But i am asking why we mount the file system separtly?

Thanks
Maro

6

how can we know why you choose the layout you have?

btw. it is /etc/vfstab in solaris!

7

hi vr_mari

/, /etc, /var, .. it's not file systems that is directory or folder

if all of this folder are in same disc or disc partition (ex. /dev/dsk/c1t0d0s1) it will be exist when you mount /dev/dsk/c1t0d0s1 to root direktory ("/")
but if this folder are in diferent disc or disc partition than you need to mount it one by one, if you just mount 1 disc or disc partition than the other folder will not exist or become an empty folder.

Regards

8

Hi edsie

Thanks for your valuable information.