Dear
I want to start a Hosting company. But confused which Control panel i select lxadmin, direct admin or CPanel where money is a question?
I need 30 gb hosting so how much ram i will add with my hosting?

I would recommend DA for price and ease of use. CPanel is more costly and takes up more ram. LXAdmin and DA use very little ram compared to cPanel, but LXAdmin isn't up to par with either DA or cPanel.

If you want to start hosting company I would recommend cPanel cause of its demand. It is little more costly and require higher ram. So approximately 512mb or 1024mb ram will be a safe option.

DirectAdmin requires less resources, cheaper and easy to use. You can go for it but if you can afford cPanel, then you should go for cPanel because it is quite rich in feature and its feature richness has not impacted its user friendliness too. Another point that you shoul consider is cPanel officially supports only RH Linux and CentOS.
Also in case of DA 512M and in case of cPanel 1G RAM should be enough.

You can run DA on less than 512, though the more the merrier. For complete newbies, cPanel can be overwhelming unless they've used it before, but straight newbies from hosted blogging sites to web hosting, cPanel is quite daunting.

You can us DA instead of Cpanel. because when you compare their features, they are not that different. just in case you choose cpanel for its Fantastico feature, know that you can do the same job on DA.

Yes, DA can be run on less than 512M of RAM (even 256M should be enough) but since you will be hosting accounts on your server and when they will go live they will certainly require resources so even in case you go for DA, you should get 512M of RAM. BTW how many sites you are going to host on your server and how much traffic they generate?