An Overview of Virtualization Technology 147
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."
Good reading until the end (Score:5, Insightful)
>>>>>
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.
>>>>>
One of the many un-sung uses for Xen is a swiss army SAN. I'm glad to see someone touch on this.
>>>>>
If you want to use Linux as your host OS, you'll definitely have to go with VMware.
>>>>>
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 [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
Re:Good reading until the end (Score:1, Funny)
That's when the phone call from Redmond
Re:Good reading until the end (Score:2)
People who understand Virtualization aren't going to rely on this type of article to make decisions, they tend to prefer whitepapers and case studies. Someone without the benefit of experience is going to lean heavy on Google to find a solution.
There's just no way to cover everything that can be covered w
Re:Good reading until the end (Score:1)
Re:Good reading until the end (Score:1, Insightful)
For example, there was no mention of the reason behind the performance differences between VMware (ie. you're emulating everything, right down to the CPU) and Zones (ie. you're running one kernel and only jailing processes).
Fortunately, it was short enough that I could get to the end without wasting too many seconds of my life. But the
Re:Good reading until the end (Score:5, Informative)
Looks like you took at least one of those quotes out of context. Here's the context:
Virtual PC doesn't run on a Linux host, so you'll definitely have to go with VMware.
Re:Good reading until the end (Score:2)
If you're a developer looking for a flexible way to test your application in multiple environments, you'll probably want to go with either Virtual PC or VMware Workstation.
If you want to use Linux as your host OS, you'll definitely have to go with VMware.
The way that reads to me is, if you want to use Linux as your host (root) O
Re:Good reading until the end (Score:4, Informative)
Every OS on a Xen system is a guest OS. Some of them just have permission to create new OS instances, or access particular bits of real hardware directly.
Re:Good reading until the end (Score:4, Informative)
So, if you think of a Xen-enabled linux kernel as Xen, you're right. But I see it as a seperately developed, ported, and integrated extension that requires a kernel to operate. Again - I believe there are efforts to get it running inside other kernels, but I don't remember.
On second thought - someone fill me in here - I'm guessing that VMWare ESX probably runs as part of some ther's OSes HAL, but of course they don't say so in the sales pitch...
*disclaimer* -- While I really like VMWare's product for functionality and ease-of-use, for performance I'd go with Xen. I'm currently involved with a project at my company to virtualize as much of our datacenter as possible, and I've been pitching Xen to the group, over VMWare, provided XenSource's product lives up to it's marketing specs.
Re:Good reading until the end (Score:5, Informative)
Xen augments the kernel, it does not replace it. The Xen hypervisor then interacts with the host (dom-0) kernel.
dom-u (guest) images can then boot using any kernel modified to interact with the Xen hypervisor. Currently we play with:
Debian (Sarge)
FC4
CentOS 4
NetBSD
As dom-u's (guest) OS's.
We have also enjoyed some success but not 100% stability bringing Win2k3 up as a dom-u.
I have deployed clusters that use Xen as a management layer and I can tell you, it *does* live up to its marketing specs. Xen's bridging is the fastest most efficient layer available, bar none. Its also a wonderful tool in helping to integrate a centralized storage area network into any size network and let people keep all of the protocols they like.
A *very* good source of information about Xen, what it does, how it does it is available on the option-c wiki (Here [option-c.com]) , they also have some ready to go Debian installers that make installation quite easy (apt-get able).
Xen + OpenSSI is another fantastic combination if you take the time to really understand the networking possiblities and set it up appropriately. Good luck with the bean counters
Re:Good reading until the end (Score:3, Interesting)
Xen does 'para-virtualization', wherein it virtualizes MOST of the hardware, but allows some passthrough to the bare metal. This requires virtualization-aware kernels and modifications to some software, perhaps. Since it's a 'lighter' application than the ESX server, it should run a bit faster.
VMWare does a full virtualization of every hardware component, like most other virtualization products (Virtual Server 2k3, Virtual PC, VMWare Workst
Re:Good reading until the end (Score:2)
ESX server is a modified Redhat kernel (2.4.9) and the ESX-specific apps, plus device modules to connect to whatever server-class hardware you have.
Re:Good reading until the end (Score:2)
Xen's host components *do* run directly on the metal, they just don't talk to I/O devices. Xen controls the processor and memory, and provides
Re:Good reading until the end (Score:2)
I hope my employer will choose Xen as their virtualization platform, but I know that much of that decision will hinge on whether or not Windows can run stably. Since the decision won't be made until next quarter, I'm crossing my fingers
Re:Good reading until the end (Score:2)
Got to stick my hands in the Windows source, and futz with it. It got quite far but it was never what you might call 'stable'. It also took about 15-20 minutes to do the first few seconds' worth of booting due to the vast, vast amount of debug information we had it dumping out of the serial port. 295MB bootlogs
The article is an outdated joke. (Score:5, Interesting)
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.
Re: P2V clarification (Score:2)
I hope you will endulge this spam-vertainment.
For the record, there are third party vendors of P2V software including Platespin and Leostream [leostream.com], whom I work for.
The VMWare P2V Assistant is arguably easier to use that Microsoft's VSMT solution, which appears to
Psst. btw (Score:4, Informative)
http://www.microsoft.com/windowsserversystem/virt
Re:Psst. btw (Score:5, Insightful)
Re:Psst. btw (Score:3, Interesting)
VMWare seems unable to deal with many object creations and many context switches, the application basically creates a COM object, deals with it and
Re:Psst. btw (Score:2)
Re:Psst. btw (Score:1)
Re:Psst. btw (Score:2)
When I do a beta for someone, I not only test the working stuff (which all gets certified first here) but also test all the experimental stuff as well. For instance, Solaris 10 is also "Experimental" and yep, I test it, each draw.
Re:Psst. btw (Score:3, Insightful)
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 Windo
Re:Psst. btw (Score:1)
And as for those licensing restrictions, they will apply to any VM software that runs your Windows Server OS. So what's the solution? Well, don't use it to run Windows, for one.
Re:Psst. btw (Score:1)
</sarcasm>
Seriously. Maybe for development, and/or if you're really doing it on the cheap. Otherwise I fail to see the benefits of such a setup.
Re:Psst. btw (Score:1)
But for development, you get a little virtual network to write your distributed apps. Or you get a little basic machine for some embedded Linux programming. Or maybe an on-demand alternative OS environment. For the home use
Re:Psst. btw (Score:3, Interesting)
Re:Psst. btw (Score:2)
Direct links (copied from Digg):
32-bit [microsoft.com]
64-bit [microsoft.com].
Do a little more digging... (Score:2)
Yeah, ESX is better in some ways, and VMware's tools are better than MS's. But, VS 2005 R2 is actually a really good product.
Netscaping (Score:5, Insightful)
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?
Re:Netscaping (Score:2, Funny)
Re:Psst. btw (Score:2)
Shameless plug (Score:3, Interesting)
Windows Licence Issues. (wrt. Virtulization) (Score:5, Informative)
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!
Re:Windows Licence Issues. (wrt. Virtulization) (Score:1, Interesting)
Put differently, if you are the only one using a book you purchased, you can make as many copies of that b
Re:Windows Licence Issues. (wrt. Virtulization) (Score:2)
Re:Windows Licence Issues. (wrt. Virtulization) (Score:2)
Informative but you left out one important thing.. (Score:2)
This is only true if you are running Windows Server 2003 Enterprise edition. And the host operating system counts as an instance. So, you load Windows Server 2003 to act as a Virtual Server host, that means the license allows you to run 3 additional guest operating systems within that host.
These are two important distinctions because the Enterprise edition is far more expensive than the standard edition. It wouldn't make se
Re:Windows Licence Issues. (wrt. Virtulization) (Score:2)
I'm a web developer and would like to start testing my sites with Internet Explorer 7 (which is currently in beta but overwrites IE6). Unfortunately MS requires Genuine Windows Advantage validation to download IE7. Can I validate both my host OS and my virtual guest OS with the same CD Key? Has anyone else encountered this problem? Am I the only one who can't stand this CD key validation crap?
(just kidding about that last quest
Re:Windows Licence Issues. (wrt. Virtulization) (Score:2)
I think I read someplace that the same licence key may not be present on a network on two hosts, but I'm not sure in what context I read that...
Perhaps download the doc I linked to earlier and read up further?
And good luck with that IE7 beast!
Strange (Score:1)
Re:Strange (Score:5, Interesting)
Anyone have a pointer to a good writeup on the differences between VT, Pacifica, and regular old software virtualization?
Re:Strange (Score:2)
What I'm most interested in:
Rik
Re:Strange (Score:2)
The article doesn't even touch on Intel's VT or AMD's Pacifica technologies. What gives?
>>>
Or being able to have win2k3 happily running as a dom-u under Xen 3 on such hardware. There's only so much you can fit in a one page blurb however. And the average reader wants it all compressed into 5 minutes or less of reading.
Topics like this , you just can't do that unless you link to many external resources allowing the reader to get more about whatever interests them.. which is what TFA
Macwintelintosh (Score:1)
Re:Macwintelintosh (Score:2)
Alas, illegal (at least in the US). Mac OS X has some trusted computing code that verifies that it is running on Apple hardware. Bypassing this code is a definite DMCA violation (hence no company will try it). AND Apple assumes a very narrow set of underlying hardware, which isn't what VMs provide - so there is another pile of effort to emulate chipset and so on.
In short, it's not going to happen until Apple wants it to happen.
Application Virtualization (Score:2, Interesting)
Hmm - I think there are a few vendors who'd disagree with that.. Softricity, Altiris, Citrix, Wise to name a few..
Re:Application Virtualization (Score:3, Interesting)
Re:Application Virtualization (Score:1)
The point I was trying to make was that the article completely ignored the areas of app "virtualisation", not
Re:Application Virtualization (Score:1)
Re:Application Virtualization (Score:2)
I run Linux as my host with VMware. Frankly, I love it. I have probably a dozen Windows images that I use each with a slatted purpouse. I even run Oracle (and it runs quite well at that) in it's own VM. The best part about doing this approach is that I am able to isolate programs that I really don't want running together, like keeping Oracle seperate from my host. Also, I have a clean enviorment where I can play with malici
what a horrible article (Score:5, Informative)
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.
Re:what a horrible article (Score:2)
Re:what a horrible article (Score:2)
Re:what a horrible article (Score:2)
Re:what a horrible article (Score:2)
Re:what a horrible article (Score:2)
Slashvertisement (Score:2)
Seriously, just two minutes on Google led to MUCH better articles, e.g. CMPNet [cmpnetasia.com], eWeek [eweek.com], and Virtualization.info [virtualization.info]
I think we've heard this before (Score:1)
I realise that it's not quite the same -- virtualisation offers multiple operating systems on a single syste
Re:I think we've heard this before (Score:3, Interesting)
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, c
Re:I think we've heard this before (Score:2)
For us, although there is an additional administrative load that's pretty minor and is vastly outweighed by the increased flexibility: being able to create new virtual servers or change existing ones at very short noti
Re:I think we've heard this before (Score:2)
Your capital outlay for the servers will be around $10k. Add in a support package for hardware and you're talking another $500 or so per year. Each box uses power, requires a KVM interface, physical space, a network port and puts a heat load onto the air conditioner. These marginal costs will add another $100 per box, so we're now looking at a 3 year cost of around $13k, not including any labor costs.
A GSX rollout would have been about
Re:I think we've heard this before (Score:2)
--This is why serious virtualization servers don't get run on Windoze. It's fine if you need to run Windows GUESTS - use a caching proxy server like Squid to download the patches, and stagger the automatic-update times for when they automatically reboot.
Re:I think we've heard this before (Score:5, Insightful)
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.
Uses of virtualization for servers (Score:5, Informative)
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.
Re:Uses of virtualization for servers (Score:2)
CoLinux (Score:5, Interesting)
Just curious.
Re:CoLinux (Score:2)
That's because no one really takes it seriously. It's not that it's not novel or not interesting, but the Linux guest runs as a *kernel thread*, not as a process. This means the guest has as much access to hardware as the host. It relies on a very well behaved Linux guest to not bring your system to a screaming halt.
If CoLinux ever adapts to run the Linux guest in a lesser ring (perhaps 1 or 2) then it will be considerably more
Re:CoLinux (Score:2)
Which is missing a QEMU trick (Score:1, Offtopic)
It is a system emulator. What it does very well is support Linux binary applications for other CPUs. Want to run an ARM binary on an x86? QEMU will do it. Want to run an x86 binary on a Sparc? QEMU will do it.
QEMU also does system level emulation.
As a special case, QEMU runs x86 on x86 as well.
VMWare and Xen don't do that.
Ratboy.
Re:Which is missing a QEMU trick (Score:4, Insightful)
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.
Re:Which is missing a QEMU trick (Score:2)
Re:Which is missing a QEMU trick (Score:2)
QEMU *can* be used as a virtualizer -- if you have a problem, report it.
QEMU can run x86 Linux on a Sparc (and so can BOCHS). Where they differ is that QEMU does so by translating the binary instructions. BOCHS has this available as a limited experimental feature, but generally interprets each instruction. Which means that BOCHS can run just about anything x86 *slowly*.
QEMU can run just about anything (x86, ARM, MIPS, etc.) on anythi
Overall Management (Score:2)
Re:Overall Management (Score:1)
VMotion is the ability to migrate running virtual machines from one physical server to another. It's roughly the equivalent of Mosix for VMs.
And it works across ESX versions, so there is no VM downtime when we need to patch our VMware farm. And it works across (some) hardware platforms, so we can upgrade our VMware farm from 2-way servers to 8-way servers, again with no downtime.
--Joe
Performance on virtualized servers (Score:3, Interesting)
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.
Re:Performance on virtualized servers (Score:4, Interesting)
VMware ESX Server provides proportional-share guarantees for CPU, memory, network and storage performance. I.e., if you always want 50% of a CPU, or 200% of 2 CPUs, or 75% of the bandwidth of a gigE nic, etc., that can be arranged.
HTH,
Keith (vmware employee)
Re:Performance on virtualized servers (Score:2)
We are aware. The problem is, if I have to guarantee 2 CPUs to make an app perform, it is more cost effective to buy a physical box - those hosts aren't cheap. We determined our break even point to be 35% of a CPU - any more than that, and we make it a physical server.
AutoSysAdmin (Score:2)
Of course a live, good sy
Re:AutoSysAdmin (Score:2)
* Total centralized command
* Dynamically provision / reprovision based on application demand, roles and rule sets
* paranoid sanity checks
* use, but don't force LVM. Make use of just conventional images.
* Integrate HPC's that can be dynamically reprovisioned.
This is done with Xen + openSSI. In a case like yours it would not be a conventional single system image, you'd be using a couple redundant wasabi style NAS's, which can also be built with Xen for additional
Re:AutoSysAdmin (Score:2)
Are we really talking about a "compute RAID" (RAIH?) available sometime this year?
Re:AutoSysAdmin (Score:2)
It could be made to work with just about anything. That's the other part of why it's taking so long to do. But yes, you could accomplish that.
Bear in mind the definition of high availability is no single point of failure.
Re:AutoSysAdmin (Score:2)
Now, if I can install it as an autoupgrade to my current (nonvirtual) LAN install, like I described in my original post, then it sounds like my dream is actually coming true
Worthless (Score:1)
meh... TFA is worthless (Score:1)
I'd guess cause thats what the author could get for free in the 10 minutes it took to write that article.
Mailing it in. (Score:2)
Ferill mentions, "On the downside, the x86 architecture does not lend itself to efficient virtualization." however he appears oblivious to Intel VT or AMD's Pacifica chips which are made specifically for virtualization.
Lets not forget that Pa
VMWare NOT Linux (Score:1)
What is he talking about? From this one sentence it is obvious that this person should have never written this article. VMWare ESX server is not Linux. VMWare ESX VMWare's own creation kernel and all. Not to say they could have barrowed parts from who knows where but it is not a 2.4.x Linux kernel or anything of that nature.
Now to the inexperienced user, installing and administration VMWare ESX you might get the impression
Re:VMWare NOT Linux (Score:1)
Drawbacks? Pish posh! (Score:1)
Re:Drawbacks? Pish posh! (Score:1)
If you are so happy with Xen, I suggest you try OpenVZ ( http://openvz.org/ [openvz.org] -- I bet you'll be even more happy. Unlike Xen, OpenVZ does not have that big I/O overhead (our tests shows Xen guests do I/O about 30% slower than native system). The biggest thing though is you can run not 3 but 30 virtual environments, and dynamically manage their resources (like adding/removing memory from the environment without any need to restart it).
Finally, live migration for OpenVZ will be released Real Soon Now.
Altiris Software Virtualization (Score:1)
The way they're pitching it to my department is that we can use it to deploy applications Enterprise wide with little testing. If a service pack or patch breaks the system it can be turned off. If a user d
Is Corporate Speak Invading Your IT Department? (Score:1)
Re:previous hot topic: virtual reality (Score:3, Funny)
Re:previous hot topic: virtual reality (Score:4, Insightful)
Just my $.02
Re:previous hot topic: virtual reality (Score:1)
Yeah, and also because you can use the virtualization software to freeze the CPU which allows you to finally defeat those Romulans in melee combat.
Re:previous hot topic: virtual reality (Score:2)
Re:previous hot topic: virtual reality (Score:2)
Re:previous hot topic: virtual reality (Score:2)
Re:previous hot topic: virtual reality (Score:2)
One of the main reason that I use VM's is that it allows me to dink around with malicious programs with hosing the host. I have even found that I don't worry if I install a malicious program or even for that matter a suspect program since I can rollback or run it under a non-persistant disk. I have a