Can you uninstall Xen? is it worth installing?

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Can you uninstall Xen? is it worth installing?

Postby MachuMan » Tue May 24, 2005 10:05 pm

Hello, Am new to this so bare with me.

I have been fooling around with linux for over a year now and i have for the past few months had the pleasure of Mandrake 10.1 (gnome) running sweet as a nut. However Xen has caught my eye as i always enjoy checking out new distros.

Basically i want to know that i wont mess up my current set up by installing xen, and know that i can ditch it if i change my mind (which i often do).

Any thought at all?
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RE: Can you uninstall Xen? is it worth installing?

Postby jjmac » Fri May 27, 2005 12:16 pm

About the only messing up it could do would be if you allowed it to install a boot loader to your mbr. As you have a Linux in already, i'd expect there is a Grub or Lilo already set up.

So, just formate a new partition for the install, and install it there. Make a boot disk for your existing installation first. When the new install wants to know if you want it to install a boot loader to your mbr ... tell it __no__.

Then, reboot into your first install and add a reference to the new install in your existing Linux boot loader config, as used by the original Linux install.

If you let it install a loader to your mbr, you will just have to configure it to see your other Linux, and whatever else you may have there. So, it's hardly worth it, as it is already set up.

Getting rid of it ... just ignore it, or remove the partition from the table list. Or over-write it.

A lot of people forget to restore the saved copy of their mbr, that the Linux loader would have made, when they do a final Linux uninstall. That is, they delete all of there Linux from the partition table list.

Basically, Lilo or whatever will still be there, and because it still needs the table entry to find its' second stage ... and the table entry has been removed, the whole thing just hangs.

In lilo you would be looking for a file called /boot/boot.0300 more than likely. No idea what Grub calls it. Also, in lilo you would do ...

]# lilo -u

to restore that file before uninstalling Linux. And even then, it's only required for the Linux that is providing the Loader service.

I haven't a clue as to how Xen performs is as an OS though.


jm

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RE: Can you uninstall Xen? is it worth installing?

Postby Nobber » Fri May 27, 2005 3:31 pm

Xen's a piece of software, not a distro. The only messing about with the bootloader you will need to do is add/modify an entry for the Xen-enabled kernel of your host distro.

Or am I the one who's lost the plot?
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Postby brian » Fri May 27, 2005 5:27 pm

nope, I don't think you've lost the plot, you have the same understanding as me :)
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Postby towy71 » Fri May 27, 2005 5:32 pm

you probably lost the plot ;-) but you are also right I couldn't find Xen as a distro on www.distrowatch.com which came back with: The distribution you requested does not exist in our database
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Postby MachuMan » Fri May 27, 2005 9:02 pm

Dudes sorry i wasnt very clear earlier. I meant i'm new to posting in forums and Xen isnt a distro its a piece of software that allows you to run multiple OS at the same time.

My question is can i uninstall xen without damaging my current mandrake install. As from what i understand it alters the kernal when you install it.

Also is it a good as its made out to be. Basically i want to know that i wont mess up my current set up by installing xen.
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Postby jjmac » Sat May 28, 2005 10:33 am

>>
Xen's a piece of software, not a distro. The only messing about with the bootloader you will need to do is add/modify an entry for the Xen-enabled kernel of your host distro.

Or am I the one who's lost the plot?
>>


Well ... i think i might be losing the plot (grin)


So, how does it work ... what is it. ?

>>
Xen isnt a distro its a piece of software that allows you to run multiple OS at the same time.
>>

My question/answer is still the same :)

>>
My question is can i uninstall xen without damaging my current mandrake install. As from what i understand it alters the kernal when you install it.
>>

Could you elaborate on how it actually goes about itself. If it installs as a kind of distro, then it should go into its own partition. So ... why would it interfere with anything.

But your saying it's a piece of sw. so ... i can't quite see it at this stage, more info please ...

Is it some sought of emulator, wrapper, or just an eloborate MS styled boot menu program.

The later one there concerns me (grin)


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Postby skecs » Sat May 28, 2005 11:01 am

In Linux Format 67, June

Virtualisation takes a leap forward with XEN - find out what a full-speed hypervisor will mean for you!

As I read it in the magazine it does alter the install and your default installation becomes virtualised as well - but is considered "special". I can't find much on removing Xen so I'm guessing it's a "get the DVD" job. The major players like AMD and Novell are jumping on board quickly as is the Linux 2.6 kernel.

http://www.xensource.com/ - the source :wink:
http://www.cl.cam.ac.uk/Research/SRG/netos/xen/ - the community :lol:
www.cl.cam.ac.uk/Research/ SRG/netos/papers/2003-xensosp.pdf (high tech report)
http://www.itnews.com.au/newsstory.aspx?CIaNID=17858
http://www.itnews.com.au/newsstory.aspx?CIaNID=17726

Hope this helps.
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Postby Rhakios » Sat May 28, 2005 3:32 pm

Xen consists of a patched kernel and some utilities.
If you install a Xen enabled kernel alongside your existing kernel then you will not have any problems as you can always go back to booting from your normal kernel if you decide you don't want Xen any more. In this respect Xen is very similar to other emulators which require kernel patches (e.g. the old version of Win4Lin). Of course you can always uninstall the utilities.
It seems to me that one of the main differences with Xen is that it requires a modification of the guest OS as well as the host, as such you can't just install anything you happen to have the install disc for. Xen is rather more of a professional than a hobbyists tool.
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Postby 1slipperyfish » Tue May 31, 2005 10:16 pm

i'm also new to this type of thing and i found that pclinux livecd install produced the effect when not choosing the bootloader option that i couldn't boot anything(not even my beloved w$ :roll: )
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Postby slowandgo » Tue May 31, 2005 11:44 pm

I just installed SuSe Professional 9.3 and it comes with Xen as an option to install. When I installed it it created a boot option in Grub. I am currently running a dual boot Dell 8300 with XP Pro and SuSe 9.3 with another option to run XEN.
I haven't played with it yet, I am a newbie to Linux so I will be taking my time working with it.

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Postby MachuMan » Wed Jun 01, 2005 12:04 pm

I see, so if i wanted to stop using xen i could just stop booting to it?

One more point, going back to Rhaikos' point.

"It seems to me that one of the main differences with Xen is that it requires a modification of the guest OS as well as the host, as such you can't just install anything you happen to have the install disc for."

When you go about installing another "guest OS" do you have to find a distro with the kernal updated or will xen patch the kernal when you install it? Also when installing other OS would you have to give them there own partitions or can they run more like "programs" in the Xen "host" OS.

Thanks for your replies so far
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Postby Rhakios » Wed Jun 01, 2005 7:51 pm

You can find pre-built disk images fro some distros here. You may be able to run it from its own partition, but most of what I have read suggest loop mounted disk images.
You know, you could always have a look at the docs to answer most of your questions:
http://www.cl.cam.ac.uk/Research/SRG/netos/xen/
and
http://wiki.xensource.com/xenwiki/XenWiki
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