we are planning to migrating samba server from RHEL 5 to 6

Please let me know the procedure.

The main points i need to know are:
1. Is there anyway to do it without giving downtime to server
2. How to take backup along with permissions.
3. Is there any procedure to migrate directly?

Please help me out!!!

Well, what 'procedure' do you think there will be?? You're upgrading a server, so you have two choices: run a system upgrade, or do a fresh install. Pick one.
No...how, exactly, do you think you'll be able to rebuild a server while people are using it??
With whatever backup software you're using now.
No idea what you mean. Again, you either upgrade or do a fresh install. Fresh installs are usually better, but that's a matter of choice.

And, you're using Red Hat Enterprise..have you called Red Hat and asked them for guidance, or read their knowledgebase documents about upgrades? You are PAYING for RHEL, right???? If you're not, you shouldn't be using it...load CentOS instead.

Actually we'll go for fresh installation. And we don't have RHEL support. Linux Questions Forums is only our support. And we doesn't have any tools to take backup. It would be kind if u suggest some. If u give us the steps we'll follow u only. Because wat we know about linux is 5%. So support us. We'll first try in in test environment then we'll go for Actual. Thanking u ppl.... Regards TPML

You need to spell out your words, please. And if you don't have RHEL support, then you SHOULD NOT BE USING RHEL. You WILL NOT get bugfixes/updates/patches/security updates, unless you PAY for them. Load a current version of CentOS instead, which is almost identical to RHEL, but FREE. This has been told to you before a few times, and in other threads, you say you're ALREADY using RHEL6.3.

And if you're not backing up a production server now, whoever is doing your systems administration now needs to do a better job. Linux has several built-in tools to let you take backups..things like tar and cpio spring to mind. And be very clear...making a COPY is not the same thing as taking a BACKUP. There are also MANY easily found utilities like bacula, zmanda, and others, that Google can point you to; start there. You also need to have something to back up TO...like a tape device, external disks, etc.

Again, back up your data, and perform a fresh install of CentOS, since you're not going to pay for RHEL. From there, restore your data/config files. That's it. If you don't feel comfortable doing this, there are many consultants that can help you.