Two Red Hat in the same computer

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Hello,

I'm working on a testing department. I want to have two operation systems on the same computer.

In one case I want to have two Red Hat Enterprise 7 on the same machine and the other a RHEL6 and RHEL7.

Today, machines with UEFI think I can only have one operating system on a computer.
How I can have two operating systems on the same computer?

Thank you very much
Regards
Valentín

VM
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Responses

Robert Krátký's picture Red Hat Guru 3240 points
10 February 2015 10:11 AM

Hi Valentín,

The easiest way is to use virtualization, i.e. to install one primary system and test all other systems in a virtual environment. However, if you really need to install two or more operating systems on the physical hardware, then it depends on the kind of setup you wish to have. The procedure will be slightly different in case you want to install all systems on a single hard disk, or if you have multiple hard disks available. Some initial pointers:

P.S. UEFI does complicate things a little, but mostly for dual booting Windows and Linux. Booting different flavors of Linux should not be a problem.

ir. Jan Gerrit Kootstra's picture Guru 6222 points
10 February 2015 10:32 AM

Even dual boot on a single disk is possible.
The laptop I work on is a Windows 8.1/RHEL 7 combination.

I would advise to use virtualization for you can run the OSes at the same time.
And you can turn of the RHEL6 and RHEL7 instance at the time of need.

At my test site (at home) I run RHEL6 and RHEL7 instances on a RHEL6 KVM hypervisor. In production we use VMware ESX with RHEL and Windows server VMs.

VM Community Member 45 points
10 February 2015 2:02 PM

Thank you both Ir. Jan Gerrit and Robert Krátký.
I have a 1TB hard drive. I installed RHEL7 half with the following partitions:

S.ficheros bloques de 1K Usados Disponibles Uso% Montado en
/dev/sda2 257898948 398040 244377324 1% /
devtmpfs 3960868 0 3960868 0% /dev
tmpfs 3969428 156 3969272 1% /dev/shm
tmpfs 3969428 9344 3960084 1% /run
tmpfs 3969428 0 3969428 0% /sys/fs/cgroup
/dev/sda3 123844092 6236088 111294020 6% /usr
/dev/sda1 511720 9776 501944 2% /boot/efi
/dev/sda4 123844092 61596 117468512 1% /usr/local
/dev/sr0 4104210 4104210 0 100% /run/media/root/RHEL-7.0 Workstation.x86_64
/dev/sdg1 15114256 13997920 1116336 93%

When I installed RHEL7 I created the mount points /, /usr, /usr/local, in standar partition with ext4, swap

Would not let me install the version that did not have a boot partition. I tried with /boot and gave me the same error.I could not install RHL7 until I created a /boot /efi partition

All this I installed a BIOS/UEFI with emulated disk AHCI.

Now I try to install another RHEL7 on available disk space. But after choosing the first option (the language) gives me an error "This program has encontered and unknown error". You May report the bug below or quiet the program".
The details begin:
anaconda 19.31.79-1 exception report
Traceback (most recent call first):
IOError: [Errno 9] Descriptor fichero erróneo
….
…

I tried to find the error in internet but there was nothing like that. Reading the report says something that partitions already exist.
When I press the button to exit the system reboots.

I installed several RHEL4 systems on the same computer. RHEL7 but I have not succeeded.

To install I had I changed the disk in BIOS / UEFI to IDE. Now just start the RHL7 of the last installation. But does not appear RHEL7 grub to start the first installation.

Partitions are now follows in the second instalation:

S.ficheros bloques de 1K Usados Disponibles Uso% Montado en
/dev/mapper/rhel-root 52403200 6487272 45915928 13% /
devtmpfs 3959852 0 3959852 0% /dev
tmpfs 3969444 156 3969288 1% /dev/shm
tmpfs 3969444 9464 3959980 1% /run
tmpfs 3969444 0 3969444 0% /sys/fs/cgroup
/dev/sda6 505580 115772 389808 23% /boot
/dev/sda1 511720 9776 501944 2% /boot/efi
/dev/mapper/rhel-home 384541232 37404 384503828 1% /home
/dev/sr0 4104210 4104210 0 100% /run/media/usuario/RHEL-7.0 Workstation.x86_64
/dev/sdg1 15114256 13997936 1116320 93% /tmp/pen

What steps must I do to have both operating systems RHEL7?

The virtualization option will study. The guest machines must run with graphical environment with 2 monitors and nvidia drivers.

Thank you very much for your answers.
Regards
Valentín

ir. Jan Gerrit Kootstra's picture Guru 6222 points
10 February 2015 2:54 PM

Hi Valentin,

grub-mkconfig is what you need
man grub-mkconfig will show you an option to discover OSes on the attached storage partitions and configure grub stage 1.5 an stage 2 for you.

Kind regards,

Jan Gerrit

james.radtke@siriusxm.com's picture Guru 6863 points
10 February 2015 2:55 PM

Hello Valentín,
Are you able to use 2 HDDs in your systems? It is not a requirement, but I believe it would make things quite a bit easier for you.
You only need partitions for /boot and /boot/efi, the other mounts can be Logical Volumes (and I recommend using LVs instead of partitions)

Number  Start   End    Size   File system  Name                  Flags
 1      1049kB  211MB  210MB  fat16        EFI System Partition  boot
 2      211MB   735MB  524MB  ext4
 3      735MB   250GB  249GB

/dev/sda2                                                 477M  113M  335M  26% /boot
/dev/sda1                                                 200M  9.3M  191M   5% /boot/efi

If you have 2 disks, you could utilize UEFI to decide which environment you want to boot to. Or you could use something like rEFInd which you would install in one of your Linux instances and it will scan for other installed OSes. One reason I recommend separate disks in the handling of /boot (I thought you had to format /boot during the install). I have some spare cycles today and I'll try to work through getting a machine built as you described (and using a single disk) because now I am curious ;-)

james.radtke@siriusxm.com's picture Guru 6863 points
10 February 2015 4:26 PM

So - I am now stuck... I tried installing RHEL 6 using UEFI and then I am at the Manual Partitioning point of the RHEL 7 install and it won't recognize the existing installation (partitions and volumes).

My next step will to attempt to go the opposite direction and install RHEL 7 first, then RHEL 6.

I believe I am going to have an issue trying to re-use /boot though.

VM Community Member 45 points
26 February 2015 9:29 AM

Hi all,

Thank you very much. I am sorry not to have answered before.

My HP Z620 computer gave problems RHEL7 to have 2 operating systems on the same disc.

I've been testing virtualization, KVM, XEN and Virtualbox. We need VMs with 2 displays a graphics card that works in pseudocolor mode.

Using XEN, access to virtual machines is done from remote and we want it locally. Using KVM virtual machines are slower than with virtualbox.

Now I have RHEL6 with virtual machines: RHEL6 and RHEL7.

In another forum I write how I can put vboxvideo in pseudocolor mode?

Thank you very much for everything

regards
valentine

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