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An Overview of Virtualization Technology
Jane Walker writes to tell us that TechTarget has a short writeup on virtualization and some of the ins and outs of using this technology effectively. From the article: "Virtualization is a hot topic in the enterprise space these days. It's being touted as the solution to every problem from server proliferation to CPU underutilization to application isolation. While the technology does indeed have many benefits, it's not without drawbacks."
From TFA:
.... [summary]'. That's a really broad and sweeping statement to make.
:) This is not a pro Xen rant but I'd like to point out that it does install effortlessly on most Debian systems in under an hour, the TFA sort of indicated otherwise.
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Novell is investing lots of effort in optimizing Xen specifically for running a virtualized copy of NetWare on top of Linux. The company's goal is to provide its customers with a migration path over to the Linux platform without giving up NetWare.
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One of the many un-sung uses for Xen is a swiss army SAN. I'm glad to see someone touch on this.
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If you want to use Linux as your host OS, you'll definitely have to go with VMware.
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That wasn't so cool. I appreciate the fact that there are just too many products available to touch on everything in one short summary article / writeup, and while the majority of the article was informative even to the lay person, you need to end a sentence like that with a 'Because
Or perhaps even "I recommend VMWare" would have been better.
It looks like the author lost interest in what they were writing near the end of the article. They talk about IRC or newsgroups being the only support options available for OS products [another sweeping statement], however have you checked out the wiki at xensource.com lately?
Just seems like TFA lost coherency after 'What's best?' It went from really informative to misleading rather quickly. If your going to go to a virtualized platform you owe it to yourself to spend a month trying each candidate to see what works best for you, not the author of whatever article you read
Microsoft has made their server virtualization software available for free.
u alserver/software/default.mspx
http://www.microsoft.com/windowsserversystem/virt
In South Florida tomorrow (Thursday), a dorky looking guy will be presenting an introduction to Xen talk. Check http://www.flux.org/ for details.
One thing the article does not speak about is licensing issues when using Virtulization. For instance MS has some twists and turns...
/ PUR.aspx
For instance:
One needs 2 different licenses if you run XP in XP.
You can run 4 instances of Windows Server for free in Windows Virtual Server.
You can run one copy of an older windows for free in Windows Vista.
(You can read more about this on the MS site...)
For Windows XP General Purpose license User Rights:
http://www.microsoftvolumelicensing.com/userights
Download and read document, section "Microsoft Desktop Operating Systems" which reads:
I) Installation and Use Rights.
a) You may install up to two copies of the software on one device.
b) Except as provided in Section II.a and II.b below, only one user may use the software at a time.
c) You may run a prior version in place of the licensed version for either or both of the copies.
d) You may only use the copies on the device on which you first install them.
e) You may use the software on up to two processors on that device at one time.
Thus this means that I can install and use XP as Bootcamp native and Parallels VM guest using only one license.
yay!
It's for this reason that virtualization is mostly hype, and won't be accepted in the enterprise. IT departments have better things to do with their budgets than to buy fancy VR goggles and data gloves for their admins.
It's not offtopic, dumbass. It's orthogonal.
With VMWare Server (ex-GSX) switching to free status, frankly I don't think they had a choice. I've been working with, and beta-testing for years, with both and the VMWare product still wins in my opinion. No win situation for MS.
"[I]t is a wise man who admits the limits of his knowledge or skill, and that pretending either causes harm." --Terry Go
Psst yourself.
You have to pay for the OS to run the virtualisation server on, you have to register to download it, and then you have to follow the usual licences- i.e (From MS own Virtual Server 2005 Technical Overview White Paper):
* you may not transfer original OEM server licenses from one computer to another,
* Each installed copy of Windows Server must be separately licensed. This means, for example, that if you are setting up four virtual machines within Virtual Server 2005 to run one instance of Windows 2000 Server and three instances of Windows NT Server 4.0 concurrently, you will need one Windows 2000 Server license and three Windows NT Server 4.0 licenses, in addition to the Windows Server 2003 host license running Virtual Server 2005.
* Each additional licence such as for IIS or databases have to be paid for each virtual machine... and so on.
Yeah, that sounds like an awesome deal.
Being bitter is drinking poison and hoping someone else will die
Just my $.02
"[I]t is a wise man who admits the limits of his knowledge or skill, and that pretending either causes harm." --Terry Go
Yeah, I was thinking the same thing. This article would have been interesting, say, 18 months ago... but with VT and Pacifica, things are different now. Without at least mentioning those, it's not very useful.
Anyone have a pointer to a good writeup on the differences between VT, Pacifica, and regular old software virtualization?
Microsoft has made their server virtualization software available for free.
Isn't this the opening phase of what Computer Business Review calls 'Netscaping' the competition? I wonder if that word will ever make it's way into the Microsoft system spelling dictionaries?
Only to idiots, are orders laws.
-- Henning von Tresckow
FTA: "If you're trying to solve one of the server-based issues like consolidation or application isolation, you'll want to go with a server solution"
Hmm - I think there are a few vendors who'd disagree with that.. Softricity, Altiris, Citrix, Wise to name a few..
Your MS licensing information is out of date. They've changed the way they handle Server 2003. Furthermore, you don't have to use Server 2003 as your base OS for VS 2005. I was using XP Pro SP2, Win'2K Server and Advanced Server, as well as Server 2003 Enterprise during the betas for both VS 2005 and VS 2005 R2. All worked just fine. Actually, I got the best performance from Win'2K AS after I really locked down the services running although that may be somewhat biased as I really know AS best and I didn't lockdown Server 2003 Enterprise. The improved memory model for Enterprise just might give it the edge if it were similarly configured.
"[I]t is a wise man who admits the limits of his knowledge or skill, and that pretending either causes harm." --Terry Go
I virtualized a Windows NT4 IIS server running an ASP application with some VB COM components, VMWare ESX is incapable of running it without insane CPU usage. A one CPU physical server is running at about 30 tx/sec with 15% CPU usage, a virtual server inside ESX is getting 90% CPU usage with barley 5tx/sec, the VMWare host itself is at 65% CPU usage with 4 CPUs.
VMWare seems unable to deal with many object creations and many context switches, the application basically creates a COM object, deals with it and deletes it, very simple logic. A bit disappointing that VMWare is taking such a huge hit.
Seriously, how did this make it on /.? The article is only a few paragraphs long, doesn't really even touch on hardware virtualization support or why its necessary (because virtualization currently sucks under 'normal' intel architecture). It even refers to qemu as virtualization, which its not, its an emulator. It mentions the program once then never touches on it again. It never explains why a person might want to use bochs or qemu even though its much slower than vmware/virtual pc. it doesn't touch on parallels or any other software out there.
Even more it doesn't even explain why the suggestions it makes are made. This article is basically a badly written advertisement for vmware or virtual pc.
I agree with you and even take it a step further. The article could not be more plain in that even though it was dated 4/7/2006, it did not take events of the last month into account which makes it totally useless in my opinion.
Three major announcements in the last month have radically changed server virtualization and made the article obsolete:
1. VMWare renamed GSX to Virtual Server and made it free.
2. Microsoft made their Virtual Server free.
3. Microsoft announced support for certain Linux distributions in their Virtual Server product.
The parts of the article that show it's obsolete in light of the above facts:
An open source solution will win the cost battle almost every time
If you want to use Linux as your host OS, you'll definitely have to go with VMware.
Also, for my own personal review - I'm a pretty heavy Microsoft user and was excited about them making Virtual Server free. Evaluating VMWare's free product against Microsoft makes Microsoft look pretty unpolished though. For instance, compare VMWare's P2V application to convert Physical to Virtual servers against Microsoft's offering which requires having a spare server lying around which must run Windows Server 2003 Enterprise with Automated Deployment Services. Give me a break - the cost becomes so prohibitive it's not even worth it. Microsoft may get there but right now their product looks like what it is - a bunch of things hastily thrown together. VMWare's products have coherence.
I'm a big tall mofo.
I have been using a few Xen based virtual servers from a commercial company recently - I used to manage physical machines. Here are some of my thoughts:
Advantages:
* Low performance overhead of Xen compared to other virtual solutions, and full OS level access as if it was a normal server.
* The cost of a hosted Xen solution is very low given that the hardware is usually managed.
* Reduced/No trips to the data center to replace hard disks etc,
* From the provider i use you can also reinstall the OS, snapshot and restore snapshots over a web interface and get access to the console. These are features you can set up in your own data center but most people never get round to.
* Quicker turn around if you need new servers, since normally they already have the spare hardware it's 1 or 2 days to get a new server set up rather than 1 to 2 weeks to order, install and configure it.
* You could do loadbalancing over several Xen Virtual hosts on physically separate machines very cost effectively. This would also mitigate against the variable performance on different Xen hosts if you used a dynamic weighting loadbalancer.
Disadvantages:
* Sometimes other users on the Xen system cause problems, or the server is restarted due to Xen related problems. This hasn't happened that often but you wouldn't currently run a system that needed 99.999% availability on a XEN virtual host if the system is vulnerable to a single server going down.
* You never know quite what your worst case performance is going to be like.
* If your system doesn't scale laterally (more servers) but only by buying a more powerful single server (some databases for example) then the Xen virtual hosting is not cost efficient.
I noticed that whenever virtualization comes up, no one ever mentions CoLinux. I've tried it once and was quite impressed. It takes a different approach entirely--rather than running in a virtualized environment, it is actually a port of the Linux kernel to run as a Windows process. (Some hardware is virtualized by this method, however, such as the network interface.) Are there any advantages to this approach? In terms of reliability, speed, etc.?
Just curious.
Consolidation technology IS important. And it is "taking off".
Servers are more powerful now. If a company decides to consolidate physical resources (to save A/C, power, rack space, buildings), they can certainly "vertically stack" applications that used to run on multiple servers onto a single server.
However, if this is done with old-hat technology, the system becomes very difficult to manage. For example, I just worked on a 4 way Opteron with 8GB of memory. The NORMAL process list was 1800 lines long!
So, containers are used to segregate the machine into more managable units.
The uptake for this may seem slow, because the clients interested in this have to replace existing gear and facilities. We are talking about major facilities: one client has 7000 assorted Unix, spread across 6 datacenters to be consolidated into 1000 servers at 2 datacenters; another has 10,000 Solaris servers. It takes years to migrate these installations.
Ratboy.
Just another "Cubible(sic) Joe" 2 17 3061
I think what makes VMware stand out from all of the rest is Virtual Center and what it brings to the table. Being able to manage ALL of your VM servers hosted on ALL of your ESX servers is a huge plus. And while this version of Virtual Center absolutely has is shortcomings, the next version of both VC and ESX are really going to raise the bar from what I've seen. The mainframe has come full circle.
"Klaatu, verada, necktie!" -Ash
The primary approach we have had to take was to stop looking at whether an app will perform on a virtual machine, and start looking at whether or not it will be cost effective for the app to perform virtually (in general, apps that will perform in the physical world can be made to perform in the virtual world if you throw enough resources at them).
It's an interesting problem. We found that our company's big push into virtualization had to be scaled back a bit - not every server is truly a good candidate for virtualization.
I've been working with VMWare and virtual servers for a while now (Xen still won't run on my main workstation at home, some ACPI problem or whatnot), but I was really amazed at QEMU. I never really tried it until I read this month's issue of LinuxJournal (all about Virtualization!) ... some of the Xen and VMWare stuff I was already familiar with.
QEMU's ability to emulate other CPUs is invaluable. You can emulate a MIPS architecture and test your favorite Linksys firmware (I believe the OpenWRT guys already do this). I would really like the m68k emulation to stabalize so I can run old Amiga stuff (or try linux on m68k). Or emulate an ARM processor , drop a PocketPC firmware on it, and test drive Windows Mobile software (or porting Linux to those devices). The possibilities are endless.
FLR
6 copies of patches to apply? Um no. Any admin working with that kind of setup SHOULD know about WSUS server and be rolling out patches (after he's evaluated them on a test rig to make sure they don't break any of his company-specific software) automatically.
And no, it's not 11 reboots. That's a really really dumb way to do it. You set a group policy to prevent the machines from automatically rebooting after patch installation. When it's time for the scheduled maintenence you shut down all the VM's, reboot the host OS, then crank back up the VMs. That's a total of 6 reboots for 6 windows machines.
Virtualisation is a fun toy and may be a useful tool if you're a multi-platform developer. But it does not seem to be a serious enterprise solution for the datacenter.
Virtualization IS a serius enteprise solution. Lots and lots of us have it in production. Then again, we know a bit about the field and don't patch every machine by hand and do unneccessary reboots.
The cost savings are real if you hire someone competent to run the machines.