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An Overview of Virtualization Technologies
PCM2 writes "Virtualization is all the rage these days. All the major Linux players are getting into the game with support for Xen, while Sun has Solaris Containers, Microsoft has Virtual PC, and VMware arguably leads the whole market with its high end tools. Even AMD and Intel are jumping onto the bandwagon. InfoWorld is running a special report on virtualization that gives an overview of all these options and more. Is it just a trend, or will server virtualization be the way to go in the near future?"
They completely forget to mention User Mode Linux, which is a well established and stable linux only offering, and many of the VPS (virtual private server) hosts you see advertised are running on UML.
It seems that as Xen makes progress, UML is getting ignored.
Since IBM practically invented virtualisation in the '60's for their mainframes (or possibly earlier (I'm not quite that old), I was quite surprised to see it missing from the Infoworld articles too.
IIRC, VMWare modelled their solution on IBM's implementation. They may have also licensed some of the technology to do it.
Fast, cheap & reliable. Pick two.
Don't forget Linux-vserver - it's very good, and very fast - as root in a vserver is root on the actual host - processes just can't "see" or kill any outside their own context. Props to Bertl.
Get your own free personal location tracker
Secondly, just think of the possibility to move server images from a physical server to another one, literally freezing it here and awakening it over there - InstaScaleOut(tm) must be a server admin's wet dream. Well, you'll poo your pants when you see vMotion in work, then. the ability to move a running VM from one host server to another without a hitch is quite something. Combine that with Resource Pools, DRS and HA and suddenly the hardware doesn't matter so much anymore!
If you stat average CPU consumption over the servers of any big size datacenter chances are you will be very surprised by the results.
...
I did this for a company with over 2000 unix servers and averages were : only 20% of the hosts would use more than 30% of the CPU
It's a known fact that for most of the projects the hardware is super sized over what's really needed, and this is one of the main advantage of virtualization : it is seen as a cost reduction process.
With that aggravating beauty, Lulu Walls.
"Migration only takes a few seconds once that's done .."
:).
An interesting way to accomplish file-based fast migration is to nfs mount an area on the target server, then use md (in the virtual machine) to place a mirror there. Then you have no need for the lengthy copy, you already have a synced up online copy there.
Not saying it's good, just saying it works (and a useful alternative if you dont have a better shared storage)
IBM is so far advanced it's not even funny.
Intel and Xen even based their virtualization stuff on old papers from IBM documentation and whitepapers.
You want to know how hardcore IBM is?
THEY INVENTED VIRTUAL MEMORY. And no I am not talking about a swap file on your harddrive, you windows wennie. I am talking about the ability every PC has to abstract memory.. It's IBM's gift to the PC that made modern computing possible.
You aren't convinced of IBM's monsterious power?
They have it setup so that when you buy a OpenPOWER machine for running Linux you can get a optional firmware hypervisor to manage multiple operating systems. And it's pretty cheap also.. For the same price as a low end Sun Opteron box you can get a low end IBM POWER5 box.
But it's not just that... Get this:
IF you buy a Xeon cpu on a add-on card you can set up the machine to RUN WINDOWS.
That's right. Run windows with a fucking x86 cpu on a PCI CARD.. Sharing the same memory and harddrives as Linux running on POWER5. On the same machine. At the same time. With NO slowdown.
Still not convinced?
How about this, for a show of IBM's utter superiority in this feild:
We are running a 2000 era IBM Mainframe with a late 1970's operating system on a 1990's operating system with 1980's era tape drives for legacy reasons.
IT'S A THIRTY-ONE BIT (no NOT 32 bits. 31bits.) OPERATING SYSTEM ON A #$%#$% 64 BIT MACHINE. It's not even like going from x86 to x86-64. They are entirely different computer archatectures. AND it runs at near bare hardware speeds. It's incredable. AND we can run Linux next to it. At the same time. And not just one Linux install, but very literally hundreds of them if we felt like it.
It's completely nuts. They got shit that makes Vmware look like Dosbox. Microsoft's 'Virtual Server' isn't even on the radar; it's completely laughable in comparision.
That and it has the worst possible user interface imaginable. Think about the worst thing you've ever seen. Some DOS 2.x nightmare. Now add a OS/2 GUI and make it WORSE. Now imagine it worse then that. Now your getting close. That and we pay out the ass for the pleasure of using it. Ok, now make it slightly worse. That's about right.
I am not an expert with Server (GSX) -- I mainly stick to ESX. I do; however run some VMware Server machines in the lab and know what you are talking about -- this symptom sounds like a memory management issue. I'd bet dollars to donuts that your guest is getting partially swapped out either because you have given the guest more memory than it really needs (this is a very common problem), you have not configured the host to prevent swapping ("Fit all virtual machine memory into reserved host RAM" under "Host Settings" in the server console), you do not have enough ram in the machine to allocate enough to the guest (and the guest is swapping itself out), or you are running services on the host machine that are dragging down the guests. You have to remember that even though VMWare Server lets you oversubscribe your system RAM, it is up to you NOT to do it. Unlike ESX, VMware Server does not have the ability to share identical memory pages among VM's, thus oversubscribing memory in Server although possible is never a good idea. In ESX, however, memory subscritption is probably the biggest advantage VMware has over any other solution at this point.
If you are using VMWare Server, please keep in mind that best practices say that you should generally NOT RUN SERVICES ON THE HOST ! It is far better to minimize the footprint of the host and create another VM to handle the services instead. There are of course exceptions to this such as when an application needs physical access to hardware that VMware can not supply or emulate, but they are not common.
If this doesn't help you, please check the VMTN forums for help; they have a points system for questions/answers and are generally one of the better free support forums for any commercial product I have ever seen.