I tried googling this first... and if I were at home I would take a chance, however, this is in my place of work, and I don't want to mess the whole server up.

We have a server running RHEL 5.3, and I need to dual boot RHEL 5.5...

I have the disk here, and I know that /dev/sda7 is where I want to install the OS.

Is there a step by step guide on how I can do this, without killing the other installation, and while still using the same grub install, so that I can dual boot?

This isn't normally my job, I am new to linux installs, and I really don't want to just jump head first into this.

I'd try it out on a spare machine first but have a look at this article on GRUB. It's the linux bootloader.

Else google "linux dual boot grub tutorial"

I don't use Red Hat but it would seem that it would not be that difficult. If you do intend to install the entire new system to one partition the only major thing you would need to do is install the bootloader correctly. If both version of Red Hat you are using, use Grub Legacy it should not be difficult. You could install the new Red Hat Grub to the master boot record and it should detect any other system on the computer and create an entry in the boot menu. Or you could install Grub to the partition (sda7) you are installing the new version of Red Hat to and create a menu entry in the /boot/grub.conf file on your old system.

If you don't understand the above, do some reading on Grub.

Whoa.. Just wanted to confirm about your comment on "I have the disk here, and I know that /dev/sda7" I am assuming that the present Linux 5.3 is already on /sda.. If this is the case.. Please DO NOT install in the same sda...

Do add another Hard disk for sdb and carry out your installation. Insert the CD/DVD and when the selection comes to install on drive just select the new drive you have added. And when the grub selection comes, The RHEL 5.5 will tell you that it has detected another linux distribution and would you like to add it to the grub.conf. Select yes please and carry on...

To figure out, if you have installed RHEL 5.3 in sda, just type df -h and see if /dev/sda[1 or 2 or3] represents /boot.

HTH,
zXi

dev/sda1 is /boot

So can I use sda7 for the additional install?

Would you like to explain why? There is no problem with installing more than one Linux distro on one harddisk (back in the times when I was distro hopping I had around 14 or so on one disk).

A server that is being used at your employer is NOT the place to be learning Linux installation, dual-boot, etc. I would use another computer to get familiar with the process.

Quite true, except the part that LDel001 has mentioned that /dev/sda7 is already partitioned under extended. If the same had been a free disk lying around, then we would hit the issue of primary partitions emptied out. To support my theory here.:

I have workstation running Linux VMS, where I have tried what @LDel001 said, and I selected sda7 to install Rhel5.5 where [sda1..7 had been partitioned by Rhel 5.3, first install].

During creating the disk layout, I had to select custom layout for installing on sda7 and when selected a new partition for /boot, it threw the error "Could not allocate requested partitions: Partitioning failed: Could not allocate partitions as primary partitions. Not enough space left to create partition for /boot."

Added that we have free disk that had NOT been partitioned and if we still have less than 4 primary partitions in first install, we could as well install. Provided LDel001 has to delete sda7 which has to confirmed in LDel001's workplace.

Again, quoting @pixellany "A server that is being used at your employer is NOT the place to be learning Linux installation, dual-boot, etc. I would use another computer to get familiar with the process."

HTH,
zXi

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Thanks for the explanation, and I totally agree with pixellany's statement, don't mess with a production system. Nonetheless I fail to see where the wanted usage of sda7 for installation implies that all primary partitions are already used.

Why are we concerned about primary vs. logical partitions??---Linux is totally happy on a logical

Let's see what you've got...

Could you open a terminal on the system of interest and run the command "fdisk -l" and post it here?

I too think it would be greatly to your advantage to take some old PC and to install RHEL with the same partition scheme as on your server, then installing RHEL again as a dual-boot.

As a cabinet maker I remember a byword of our trade, that it is better to measure many times and to cut once than to suffer the consequences of measuring incorrectly, making the wrong cut and having no recourse.