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Let's step back a bitLet's step back a bitPosted Jun 4, 2009 1:05 UTC (Thu) by ras (subscriber, #33059)In reply to: Let's step back a bit by BrucePerens Parent article: Xen again
I am just exploring the implications of this issue myself.
When I going out and try to buy CPU cycles, the most attractive way to do it right now is a Xen VM. There are other options - shared hosting, VMware and probably others. All have warts compared to a Xen VM. It is really nice to be able to configure and debug my VM on my laptop, then send it to the hosting provider. So that is point 1: unlike KVM or any other solution described here, Xen is out there, in the real world. Because KVM isn't, it is in a practical sense unless for one of the major applications of VM's - cloud computing.
Point 2 is that many of those Xen images out there are para-virtualised for speed, so I can't use KVM to develop them.
Point 3 is I want to run the latest Linux kernel as my Dom0 - principally because nothing else seems to work on modern hardware. Applying the Xen patches myself is an absolute PITA.
The end result is not having Xen is making Linux hard to use in an emerging platform - cloud computing. I don't doubt there are real issues - the fact that Xen uses the Dom0 to talk to the hardware sounds to me like it has the makings of a real ugly patch. However Xen isn't a webcam that can be ignored. Xen is an entire platform - like Windows or Linux. And it is an open source solution locked in battle with closed alternatives. I want it to win - after all I could just use VMware. If Xen doesn't win, possibly no open source solution will. KVM is not even a player in this space.
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Let's step back a bit Posted Jun 4, 2009 1:23 UTC (Thu) by ncm (subscriber, #165) [Link]
This is a very interesting and persuasive view. I wonder, though: if Xen can be hosted on KVM, then the ultimate choice doesn't affect you, does it? You can run your Xen image on an old Xen or a new Xen, and not notice the difference. Where am I confused? Is it that a KVM Xen can't run your paravirtualized image?
Let's step back a bit Posted Jun 4, 2009 1:51 UTC (Thu) by ras (subscriber, #33059) [Link]
ncm: Is it that a KVM Xen can't run your paravirtualized image?
Firstly, beware I am trying to do this as we speak. I've tried things. Some of them didn't work. But maybe it is just because I don't have a clue.
There are two issues here. One is I don't seem to get a choice as to what DomU I am running. The VM hosting provide couple and I choose one. If I want to work on it locally, I image it and have a fiddle. The essential point being, I can't choose one that suits KVM. On the other hand, if there is some magic way I can make any image run fine under KVM, and back again 100% reliably then I am mostly satisfied. Right now I haven't found that way. As I said, this is possibly because I need a clue.
Secondly, I would like to use the same tools for managing the DomU the hosting provider does - it just makes it so much easier to understand what is going on. In other words, I want to run the xen tools in a Linux Dom0. This is very much a secondary consideration for me though. It is possibly more important from the Xen world domination point of view as you want to make it as easy as possible for the hosting providers, and right now they have to be very picky about what they use as their Dom0.
Currently I can use Linux 2.6.26 as my Dom0. Sadly a big chunk of my peripherals aren't supported by 2.6.26. In fact some aren't stable under 2.6.29 (wireless causes the machine to freeze if I use it heavily), so right now I am eagerly awaiting each new kernel release. But porting the Xen patches to each and every kernel release is simply too much work.
Let's step back a bit Posted Jun 4, 2009 6:34 UTC (Thu) by jamesh (guest, #1159) [Link]
An earlier post linked to http://kraxel.fedorapeople.org/xenner/. Can you use that to run the guest images from your provider?
Let's step back a bit Posted Jun 4, 2009 6:49 UTC (Thu) by ras (subscriber, #33059) [Link]
It may well be exactly what I want. Thanks.
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