Trying out Xen



  • I set up a server and installed Xen. I've never used it before, so are there special images for PV or do you install from a regular ISO and then install packages? If there are special images, where do you get them?



  • Like anything, it is up to any particular VM maker to make whatever images you would want. If they don't offer them, you don't have them. It's the same as any hypervisor vendor.



  • You can install from ISO or whatever. Only a few operating systems support for PV, Linux being one of them.



  • What Xen platform are you using? OpenSuse? Ubuntu?



  • @scottalanmiller I installed on CentOS 6.7. I wasn't sure what the best distro was to use.



  • @johnhooks said:

    @scottalanmiller I installed on CentOS 6.7. I wasn't sure what the best distro was to use.

    Well current is always better than old. If you are going to use CentOS I would stick with 7. Running on CentOS 6 means you have a quite old Xen version.

    OpenSuse has always been the leader in virtualization platforms, just as it is with clustering and storage.

    XenServer is built on CentOS, but is completely custom so is a special case.



  • If you are new to Xen, normally you would use the prepackaged XenServer instead of installing Xen to a Linux distro. But that's how we used to do it in the old days before the Xen distros existed.



  • @scottalanmiller I tried but there were no packages for CentOS 7. Ok, I'll try that then. I didn't know if it was better to use XenServer or try to install it and do everything manually. So if I'm understanding correctly, if I wanted a PV image of Ubuntu or CentOS I would use one from Xen/XenServer?



  • @scottalanmiller Also, do you still feel the same way about KVM as I've read from you previously? Most of what I saw was a few years old, so I wasn't sure if it has matured enough to be something you would recommend.



  • @johnhooks said:

    @scottalanmiller I tried but there were no packages for CentOS 7. Ok, I'll try that then. I didn't know if it was better to use XenServer or try to install it and do everything manually. So if I'm understanding correctly, if I wanted a PV image of Ubuntu or CentOS I would use one from Xen/XenServer?

    I think that looking for an image from anyone is an odd approach to virtualization. Conceptually I'm not sure why you would want this. Don't look for them at all. If you want a standard image, install, customize and make your own. Don't look for it from someone else unless it is some sort of appliance deal where that is the only option.



  • @johnhooks said:

    @scottalanmiller Also, do you still feel the same way about KVM as I've read from you previously? Most of what I saw was a few years old, so I wasn't sure if it has matured enough to be something you would recommend.

    It's matured but in generally everything about KVM falls still into a "why?" category. If other options did not exist it would be excellent. But as other options do exist, what's the value?



  • @johnhooks said:

    @scottalanmiller I tried but there were no packages for CentOS 7. Ok, I'll try that then. I didn't know if it was better to use XenServer or try to install it and do everything manually.

    XenServer is fully packaged, with all the tools, basically fully up to date.



  • @scottalanmiller I guess I'm still confused on the difference between a paravirtualized guest and a regular install from an ISO.

    I guess I just assumed there was some kind of value for KVM since Red Hat is pushing it so much.



  • @johnhooks said:

    I guess I just assumed there was some kind of value for KVM since Red Hat is pushing it so much.

    Of course there is, tons of value. But you aren't Red Hat, so what is valuable to them isn't necessarily even remotely valuable to you. Companies push things because it is good for THEM, not you. The more someone pushes, the more it is valuable to them and not to you.



  • @johnhooks said:

    @scottalanmiller I guess I'm still confused on the difference between a paravirtualized guest and a regular install from an ISO.

    Those are completely unrelated concepts. One is about installation, the other is about the platform.



  • @scottalanmiller oooh ok. I must have misread something somewhere. I thought I needed an image that was pre set up for paravirtualization for compatibility. I apologize, I'm a moron. Thanks a lot!



  • @johnhooks said:

    @scottalanmiller oooh ok. I must have misread something somewhere. I thought I needed an image that was pre set up for paravirtualization for compatibility. I apologize, I'm a moron. Thanks a lot!

    Nope, no need for images for anything. You can use them, of course. You probably read from a site that was talking about images and if you are using images, then yes, they would need to be expecting to be on PV rather than HVM when they are made. But if you are installing normally, you select PV or HVM at the time that you create the VM on the Xen side of things.



  • @scottalanmiller Makes more sense now. Thanks again!



  • No problem. I would definitely switch to XenServer, it has more obvious interfaces and is much less "power user" focused.



  • @scottalanmiller I just downloaded it and am putting it on a usb. What do you recommend for a client? The only Windows machine we have is my wife's old laptop. Will virt-manager work or should I use something like OpenXenManager?



  • @johnhooks said:

    @scottalanmiller I just downloaded it and am putting it on a usb. What do you recommend for a client? The only Windows machine we have is my wife's old laptop. Will virt-manager work or should I use something like OpenXenManager?

    You CAN run it from USB, but it is not simple like VMware, sadly. That's something that they REALLY need to work on. It can work, but it is a huge pain.

    You can virtualize XenCenter on top of XenServer, but obviously that has a few limitations (can't start itself, for example.) You really should use XenCenter to at least get started with XenServer, you can test out any other clients that you like after seeing what the "official" one is like. But if you have no Windows, you'll have to just experiment.



  • @scottalanmiller Oh ok. I'll just install it. I found someone who has it running in Wine. I'll give that a shot. It does look really nice. Thanks again, I owe you a beer.



  • Had not considered running it in Wine, that's a great idea. Citrix wants to get it ported to Linux but there is something holding them back.



  • @scottalanmiller I wouldn't be surprised if it's some kind of Windows copyright nonsense or something of that nature.



  • @johnhooks said:

    @scottalanmiller I wouldn't be surprised if it's some kind of Windows copyright nonsense or something of that nature.

    I can't imagine how that would be even possible. How could Microsoft have a copyright on the Xen console?



  • @scottalanmiller Oh I was thinking more along the lines of some protocol that was used, something like that. But then again, I have no clue what I'm talking about.



  • @johnhooks said:

    @scottalanmiller Oh I was thinking more along the lines of some protocol that was used, something like that. But then again, I have no clue what I'm talking about.

    The protocols are all Xen protocols. It's Xen talking to Xen. Xen is open source.



  • @scottalanmiller I guess I just always assume if they a company has developed it and can't move it to another platform, it's because of some legal matter. Kind of like Apple with their crazy patents. Such as their patent on "Touch screen device, method, and graphical user interface for providing maps, directions, and location-based information"



  • @johnhooks said:

    @scottalanmiller I guess I just always assume if they a company has developed it and can't move it to another platform, it's because of some legal matter. Kind of like Apple with their crazy patents. Such as their patent on "Touch screen device, method, and graphical user interface for providing maps, directions, and location-based information"

    If Microsoft had the ability to "own" anything you made on their OS, no one would ever use it.

    Apples doesn't have anything like that either. No one does.

    Citrix just has a lack of resources or wants to port Windows only code or something simple.

    When people can't move between platforms 99% of the time it is because they don't have the manpower and 1% because of a technical limitation making them have to develop something completely new.



  • Please remind where the difference between Xen and XenServer - I take it Citrix still owns XenServer - but what? it's free now?