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Old 06-25-2011, 08:30 AM   #1
mike_rhce
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One big RHCSA topic -- Virtualization


One significant new feature for the RHCSA (that's the Red Hat Certified Systems Administrator) is the introduction of the Kernel-based Virtual Machine (KVM) as Red Hat's preferred virtualization solution. Well, while it's not explicitly listed in the RHCSA objectives, KVM is the only virtual machine software available with RHEL 6.

One issue with KVM -- it's available from Red Hat only on 64-bit systems. KVM server software isn't even included in the 32-bit RHEL 6 release.

One way you may be able to get around this for purpose of your studies -- use a rebuild distribution such as Scientific Linux 6. From what I've seen, their 32-bit release includes KVM (However, I haven't tried that SL 6 feature on my own physical hardware.)

So for these five objectives

Access a virtual machine's console
Start and stop virtual machines
Configure a physical machine to host virtual guests
Install Red Hat Enterprise Linux systems as virtual guests
Configure systems to launch virtual machines at boot

You'll need to learn to use KVM. Do so, and you'll master one important topic for Linux sysadmins everywhere.

Last edited by mike_rhce; 06-25-2011 at 08:32 AM.
 
Old 06-26-2011, 06:31 AM   #2
stef80
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Just checked on a i386 port of RHEL 6.1, and yes, there is no "Virtualization" group of packages available (contains qemu-kvm).
However, every Intel/AMD x86 CPU today is 64-bit and almost all have enabled hardware assisted virtualization (needed for KVM) so it should not be a big problem to run x86_64 RHEL port as KVM host .

Last edited by stef80; 06-26-2011 at 06:46 AM.
 
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Old 06-26-2011, 09:03 AM   #3
mike_rhce
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What you say is true; however, students with fewer resources may still have 32-bit systems. It bothers me that Red Hat is effectively requiring such students to upgrade. But that is life w/r/t the latest technology, and the Scientific Linux 6 32-bit loophole should work for such users.
 
Old 06-26-2011, 09:15 AM   #4
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I think hw enabled virtualization is more of a problem here then 32 bit arch .
If you got 32-bit chip, I'm pretty certain it does not have VMX/SVM extensions since that stuff came after x86_64 era.

So even if you use i386 SL 6.0 you still need to have modern 64-bit chip with VMX/SVM for KVM to work.

Last edited by stef80; 06-26-2011 at 09:29 AM.
 
Old 06-26-2011, 09:49 AM   #5
mike_rhce
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Yup, it's relatively rare especially on older laptops. I remember checking countless BIOS menus in stores before buying a laptop in '06. I didn't keep my notes, so can't say whether all the candidates were 32- or 64-bit. But I'm pretty sure that HVM could be enabled on slightly older 32-bit desktop systems; HP comes to mind, based on user reports. Of course, user reports have been wrong before.

In any case, I did (and do) recommend the use of 64-bit systems to work with KVM on RHEL 6. (Even the lowly i3 qualifies, IIRC.)
 
Old 06-14-2012, 02:08 PM   #6
ygor
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Question Virtually ?

I am one of a team of 4 Linux admins who are pooling our resources to cram for the RHCSA/RHCE certs in a series of brown-bags.


About this virtualization: I am of the belief that we need a hardware "victim" to install RHEL-6 on and then metastasize various KVM-clones onto it.

A suggestion was made by a co-worker outside this team to try running a hypervisor on a VM running on a Windows laptop.


Is this possible / sane / advisable ?
 
Old 06-14-2012, 10:53 PM   #7
mike_rhce
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Dear ygor,

IMO, VMs on Windows are the most difficult option. First, unless you directly install RHEL 6 (or an equivalent like CentOS/Scientific Linux) on appropriate hardware, you'll need "nested" VMs.

Until recently, the only such option that I'm aware of is VMWare ESX -- and that has a customized Linux kernel that installs directly on hardware, without any intermediate operating system.

I gather that VMWare Workstation 8 makes "nested" VMs possible. I have not tested it. The reports I've seen suggest that its sloooooooooooooooow.

In addition, when I ran VMs on Windows (years ago), I had to defragment them frequently. And defragmenting the files I used for individual systems (5GB) file (if my memory is correct) took several hours.

For the systems I specify in the book, you'll need an 80 GB file just for the VM. I have a sneaking suspicion that such a defrag would bork a day or two into the process. Even if successful, I do not know if that would create problems between the nested VMs.
 
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Old 06-14-2012, 11:13 PM   #8
stef80
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Quote:
Originally Posted by ygor View Post
I am one of a team of 4 Linux admins who are pooling our resources to cram for the RHCSA/RHCE certs in a series of brown-bags.


About this virtualization: I am of the belief that we need a hardware "victim" to install RHEL-6 on and then metastasize various KVM-clones onto it.

A suggestion was made by a co-worker outside this team to try running a hypervisor on a VM running on a Windows laptop.


Is this possible / sane / advisable ?
You can do regular VMs without KVM, and cover all the other objectives.
Real hardware would be best option for KVM.
 
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Old 06-15-2012, 08:13 AM   #9
ygor
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Cool Thanks !


Thanks for both replies. The sanity check helps.

I have no problem trying something a bit radical, but I prefer to avoid trying something foolish.

I can "borrow" some hardware for the time it should take to cram, but it involves a bit of pilotics.
Whereas the nested VM's (if practical) is something I could have tried with current resources.

I will go with the hardware. Sounds safer.

Thanks again.
 
Old 06-17-2012, 11:29 AM   #10
stef80
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About hardware, it doesn't have to be anything exotic. Cheapest CPU today should be more then enough for few VMs. Intel Celeron G530 or AMD Athlon II X2 or X3.
 
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Old 06-17-2012, 01:18 PM   #11
ygor
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Thanks again

Every info-tidbit helps.
 
Old 06-18-2012, 09:16 AM   #12
tietack
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stef80 is correct -- I was able to set up a working set of KVM-based VMs on my Dell laptop from '06 (with a T7200 CPU).

The key is the BIOS/UEFI -- if it's an Intel CPU, there's normally a toggle in that menu where you can enable hardware virtualization. (AMD CPUs that support hardware virtualization have no such limit.)

When successful, you'll see either a vmx or svm flag in the /proc/cpuinfo file. So if you want to be sure, get a "Live" CD or DVD, toggle the hardware virtualization setting in the BIOS/UEFI menu, and check the contents of the noted file.
 
  


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