what is the advantages of having separate filesystems for /var /tmp /opt /home

[senthil_kumar_1]

Hi All,

We can have these "/var, /tmp, /opt, /home and /usr" filesystems separately or under /.


1)what is the advantage of having those filesystem separately?

2)what i think is, if we are having all those filesystems under / and we are assigning bulk of space (like 30GB or 40GB) then all those filesystem can use this much space. am i correct?


3)But if we are having separate filesystem like /var - 3GB, /home - 4GB, /tmp - 3GB. here if /var is getting full but /home is occupied only of 1GB, at this situation /var can not use the space of /home or other file system's space. am i correct?


4)So what is the best practice that having separate filesystems or having all under /?

5)what is the industry standard?

[James R. Ferguson]

Hi:

When you cold-install (and that's the desirable way whenever you can), you can _choose_ your logical volume sizes. There is nothing to prevent you from accommodating your immediate and projected needs at that time.

You would be remiss if you didn't have OnlineJFS. Aside from using OnlineJFS to resize filesystems you most certainly want it for its filesystem snapshot ability (for backups) and for its additional filesystem mount options with which you can optimize performance according to what the filesystem needs to do (permanently or temporarily).

While different than Linux environments, the idea of separate filesystems (logical volumes) for the standard Unix directories is to provide isolation and some protection from filling you whole disk when a rogue process or stupid mistake creates gigabytes of output.

The intended contents of the various filesystems can be seen in:

http://docs.hp.com/en/B2355-60130/hier.5.html

Regards!

...JRF...

[Johnson Punniyalingam · Accepted solution]

1) Better management of Operating file system

keeping separate file system /var /tmp /opt /usr - Good Practise

2) Yes Right / correct / :)


3) Correct


4) best practice --> having separat filesystems

5)what is the industry standard?

created seprate file system

[Pete Randall]

If they are all grouped together under /, then filling any one of them fills / and your system stops dead. A runaway program writing to /tmp can kill you system.


Pete

[Tingli]

System might hang if / is 100% full. If you have the file systems isolated from each other, you can avoid such bad situation such as some process or users have a huge file created.

And especially nowadays, the disk is much cheaper you can always have a larger file systems.

[James R. Ferguson]

Hi (again):

I must remember that you like enumerated answers.

Why would you think #3 would be otherwise? Do you understand the concept of a logical volume with a filesystem within?

As for #5, why would you think that every flavor of Unix (and let's include Linux, here) would have any kind of universal standard? The history of Unix alone (yes, before Linux appeared) would tell you that that was unlikely. There, you now have more reading and thinking to do!

Regards!

...JRF...

[Steven E. Protter]

Shalom,

1)what is the advantage of having those filesystem separately?

If those file systems fill up, the system won't halt. If /var fills the system will fill up.

2)what i think is, if we are having all those filesystems under / and we are assigning bulk of space (like 30GB or 40GB) then all those filesystem can use this much space. am i correct?


This is how Linux is often done. Again its hard to fill up a filesystem that big, but I've seen it done. If you do your HP-UX system Linux style, and fill up the root filesystem, an HP-UX system will halt.

3)But if we are having separate filesystem like /var - 3GB, /home - 4GB, /tmp - 3GB. here if /var is getting full but /home is occupied only of 1GB, at this situation /var can not use the space of /home or other file system's space. am i correct?

You have to plan more, but in the end your system is less vulnerable to user stupidity, and therefore more reliable.


4)So what is the best practice that having separate filesystems or having all under /?

Best practice is to have filesystems set up with appropriate sizes and the recommendation of the Ignite installer. /var/tmp being separate is often done and helps avoid full /var filesystem.

5)what is the industry standard?

That varies place to place. HP-UX is generally not done Linux style. I have worked a number of places due to my recent employment displaycement. /var/tmp is pretty widely used.

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