system hangs
 

When copying or moving large files(like videos) through command line from one place to another ,system hangs in the middle,so reboot required .Today this happened 6 times,Am feared to do such actions.Using RHEL5..

I doubt a reboot is required, when you're copying a file.

You need to provide some useful information, before you can get help. Such as what file(s) you're trying to copy, using what command, and where the file is coming from and where it's copying to.

What exactly are you trying to do? And again, since you have RedHat Enterprise linux, have you contacted their support, since you're paying for it?

No no,after system hangs what will I do ? Reboot the system is the only way.
copy using cp,moving with mv,from my harddrive to pendrive,one harddrive to another harddrive,to lvm partitions,etc...
I am using RHEL5 since last 2 years,it's the student edition given by the redhat training institute. .why will I pay for that ?

When you say system hangs, you mean that EVERYTHING freezes? I am assuming you are running a WM, so have you tried switching to a terminal? ctrl+alt+F1 will do that. Are there any other symptoms or descriptions of the problem that you can provide? If you can switch to a terminal after your graphical freezes, post the output of:

If its just the terminal that seems hanging, try copying a comparatively small file to confirm if its just the copy process

Yes everything freezes,neither keyboard nor mouse works.I cant switch to terminal or pseudo terminal.Nothing works.
I have to forcefully reboot the machine after all.

Not only the terminal hangs but the whole system freezes.Small files with kbs or some mbs,while copying or moving,work successfully.

Is there anything in /var/log/messages that might help diagnose the situation?

Also, instead of doing a hard reboot with the power switch, try this key combination:
alt+sysreq+[in order and one at a time: r, e, i, s, u, b].

Is there a key sysreq ??

Some keyboards have it labeled, others do not. It is the print screen key as well.

But the key combination I gave you is not right. It is ctrl+alt+[other keys]

maybe its just taking along time
when i am using Damn small linux and cp'ing large files the mouse barly moves
and pretty much nothing responds for aout 7 minits

Ok, but you still haven't answered the original questions:

- WHAT file(s) are you copying?
- WHERE are you copying them from/to?
- EXACTLY what are you trying to do?

Have you checked the logs? Any hardware errors?

And again, have you contacted RedHat support, since you're paying for it with your RHEL?

No log during that period ,I checked /var/log/messages.I already answered ur questions by replying your previous post.
Yesterday I found an useful topic about the services that run during startup of the system.It told which unnecessary service to stop and which service to continue.
So I think I messed up with some of the services.
I am now double checking that topic..

I did it,I just started some of the stopped services and done,no freez,no hangs..Everything is ok now.

No, you didn't, but glad you solved your problem. Since the mystery problem was solved/caused by a system service, how about sharing the answer with everyone else?