# Choosing a VPS plan: Xen or KVM?

## D-LINC

Hi. I'm shopping around for cheap VPS that will run Gentoo. I want to go the VPS route because the prices seem to be cheaper than the dedicated servers, but to be honest I don't know that much about virtualization. I keep running into sites that offer various plans under different virtualization systems. Could someone explain to me what the practical differences are (administratively speaking) between having a Xen VPS, and a KVM VPS?

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## cach0rr0

from the administrative side, with access to the guest only, the functional differences will basically be nil. 

At work we lease out a couple hundred; some openvz, some kvm, some xen, the only particularly annoying ones are openvz, since we cant easily add features to the kernel that might be missing for something we need. KVM and Xen both provide paths to do this - I guess the first/primary question, do you plan on running gentoo guests, and do you plan on rolling your own kernel? 

IMHO where you see the bigger difference is in administering the host OS, but since your VPS provider will be doing all of that, that element isnt an issue for you. 

Sorry if that's an abbreviated response, I'm running on zero sleep, pulling an all-nighter waiting for a FedEx package (new phone!) so I'm speaking quasi-gibberish. If you have specifics, e.g. "my VPS will be used primarily for this, and I anticipate needing to customize $foo", that would help immensely.

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## frostschutz

In both performance and usability, it heavily depends on how its set up on the host side (both soft- and hardware) so it's hard to say. Both Xen and KVM allow you to run your own kernels, and load your own kernel modules, but not always does the host actually allow you to do just that. When working with virtualization on a real root server, I very much prefer using KVM over anything else. I'm also renting a KVM VPS atm, but its host is not set up the way I like (no virtio etc.) and the network speeds drop drastically when under CPU load. But it's cheap so oh well.  :Wink: 

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## NeddySeagoon

D-LINC,

Audition some.  Some vendors give you a free trial and many have a month by month contract, so you are not tied in.

At home, I run KVMs with a Gentoo hardened guests on a Gentoo hardened bare metal install.

I also rent a Xen VPS.  I get to make my own kernels and install whatever Gentoo I like on it. I have no idea what the host OS is.

Amazon will also give you a free slice of their cloud for a year - thats something I must play with.

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## NeddySeagoon

frostschutz,

What don't you like about virtio ?

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## cach0rr0

 *NeddySeagoon wrote:*   

> frostschutz,
> 
> What don't you like about virtio ?

 

I read it as the lack of virtio being what he dislikes

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## D-LINC

In the case of KVM: it is transparent hosting on the client's side, right? I mean, if I am running Gentoo inside a VPS provide through KVM, my kernel or other system utilities don't need to know it is a VPS, right? I just build my kernels and compile stuff like normal?

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## NeddySeagoon

D-LINC,

Thats correct.  However there are some performance advantages to using the virtio interfaces.  You can only do that if the host offers them.

If not you will need to use the emulated hardware.

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## papahuhn

 *frostschutz wrote:*   

> In both performance and usability, it heavily depends on how its set up on the host side (both soft- and hardware) so it's hard to say. Both Xen and KVM allow you to run your own kernels, and load your own kernel modules, but not always does the host actually allow you to do just that. When working with virtualization on a real root server, I very much prefer using KVM over anything else. I'm also renting a KVM VPS atm, but its host is not set up the way I like (no virtio etc.) and the network speeds drop drastically when under CPU load. But it's cheap so oh well. 

 

Frostschutz, what's your hoster? I'm looking for a cheap KVM/Xen/VMware virtual machine.

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## frostschutz

 *cach0rr0 wrote:*   

> I read it as the lack of virtio being what he dislikes

 

That's what I meant.

 *papahuhn wrote:*   

> Frostschutz, what's your hoster? I'm looking for a cheap KVM/Xen/VMware virtual machine.

 

Hetzner. I used to have a Xen VM with Synserver, but they didn't let me use my own kernel there and so I was stuck with 2.6.18. Might have changed in the last two years though, mind.

I have no experience whatsoever with VMware, sorry.

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## papahuhn

 *frostschutz wrote:*   

> I used to have a Xen VM with Synserver, but they didn't let me use my own kernel there and so I was stuck with 2.6.18. Might have changed in the last two years though, mind.

 

That surprises me. I didn't know that Xen VMs could share the dom0's kernel. As I know Citrix' XenServer, one has fully virtualized hardware and can use custom kernels and everything.

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## frostschutz

I think there was some security issue or other some years back that could allow guests to gain root access on the host with a modified kernel or sth and that's why they didn't allow it. There was also kind of a lull in development in Xen back then, or at least it felt to me that way. Anyhow, I've been using KVM ever since both host and vm and very happy with it...

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## cach0rr0

 *frostschutz wrote:*   

> 
> 
> Hetzner. I used to have a Xen VM with Synserver, but they didn't let me use my own kernel there and so I was stuck with 2.6.18. Might have changed in the last two years though, mind.
> 
> I have no experience whatsoever with VMware, sorry.

 

I use Hetzner as well, so far so good. I have 12 VPS's with them (CentOS) and one physical box (comes with CentOS, but,you use their Debian rescue console to install Gentoo). Blowing away their OS and installing your own is easy. It has been maybe...9 months? And no hiccups. 

(thanks to the chap who suggested it to me all those months ago! not naming names)

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## TigerJr

 *D-LINC wrote:*   

> Hi. I'm shopping around for cheap VPS that will run Gentoo. I want to go the VPS route because the prices seem to be cheaper than the dedicated servers, but to be honest I don't know that much about virtualization. I keep running into sites that offer various plans under different virtualization systems. Could someone explain to me what the practical differences are (administratively speaking) between having a Xen VPS, and a KVM VPS?

 

XEN

Thats my choice

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