What is Digg?9 Comments
- xocomil, on 10/12/2007, -0/+3Depends on the version of VMWare that you are using. Currently, the free VMWare Server version run a virtualization layer inside the host OS. It emulates all the hardware and passes all the system calls back to the host OS to be processed. Xen and other hypervisor virtualization programs allow the guest OS to access the hardware directly. The main problem that these programs have had in the past is that they require the guest OS to be recompiled to use the virtualization hooks necessary for the virtualization to occur. This hasn't been a problem for Linux/Open Source OSes because you can easily get access to the source and make the changes. The problem has mainly been with people wanting to run Windows on hypervisor type virtual machines. You usually have to download hacked versions of the OS from sometimes shady sites or not run it at all since Microsoft hasn't been to friendly with the Open Source community. I have never tried to run OS X under Xen and so I don't know about how Apple feels about Xen. With the new OS X for x86 processors, I may experiment in the future. The one upside to this problem is that the new Intel chips (and AMD will soon include support) have support for this kind of virtualization built into the processor. This means that you can virtualize currently unsupported OSes without having to modify the kernel. In fact, Intel and AMD's support for hypervisor virtualization is what made me excited about Xen. I currently use VMWare to test my Windows based installers on a virtual machine on my Linux box. The problem is that because I have to use a machine emulator (or shell out big bucks for their hypervisor-like technology) my installer/program tests are tested at about 65% of the capabilities of my Linux machine. I'm excited about getting a better, lower-layer virtualization that is free and doesn't require me to use a hacked kernel. That way, I know that the kernel will behave the same way as it will on a pure Windows machine.
- aitzim, on 10/12/2007, -0/+3Xen is supposedly faster since it only does part virtualisation (less overhead).
- Flankk, on 10/12/2007, -0/+3Xen is open source.
- swaxhog, on 10/12/2007, -0/+2What are the advantages to using Xen now that VMware gives their Server version (Windows & Linux editions) for free?
- Lodarage, on 10/12/2007, -1/+3Here's the printer friendly version:
http://www.howtoforge.com/book/print/1169
Corale cache version of the above page:
http://www.howtoforge.com.nyud.net:8090/book/print/1169 - snark42, on 10/12/2007, -0/+1Xen gives minimal disruption to other hosts when mis-behaving hosts are told to go crazy. What about over-all performance though? Xen blows VMWare away... so how do you balance these two issues? I see a run-away domain causing a minimal disruption as ok... maybe that minimal change is unacceptable to you? The IO issue is a little bogus, but maybe using a different type of underlying IO system can helpy ou mitigate that?
- Surferdude, on 10/12/2007, -0/+1Just remember, Xen 3.0 is still in testing so its probably not the best to use in production.
- kilian, on 10/12/2007, -0/+1Great tuto! Definitively dugg.
- mib1969, on 10/12/2007, -1/+1Another problem with the Xen approach is that their guest machines don't have quite the same kind of isolation you would get out of VMware. So if stability in your host and other guests is important, VMware is your only option: http://people.clarkson.edu/~jnm/publications/isolationOfMisbehavingVMs.pdf (table on page 4 shows that VMware is the only virtualization technology where a misbehaving VM will not crash or impact other running VMs). This is not a trivial issue if you want to use virtualization in production (again, VMware is the only company that offers a non-hosted solution with its ESX product line).
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