Seconded on the KVM / Libvirt combo here. I prefer virsh for all my stop / start / force reboot that damn windows server needs. Virsh provides a nice terse interface via ssh (just the way I like it)....
The benefits here will include a more high performance display (better rendering of media, accelerated graphics, etc) as well as remote audio, and I believe they've also got something in there for client-side storage and usb etc. [http://spice-space.org/]
Still my vserver provider moved me from openvz to xen. I hear lots of people prefering xen for things which needs to be closer to the hardware. And some other arguments which sounded worth considering. But since I already forgot them...
Anyway, my personal feeling is that xen is dead.
What the Linux world is finding, however, is that with hardware-supported virtualization, bare-metal hypervisors don't offer any additional performance benefits anymore. That's why Linus chose KVM instead of Xen as the official hypervisor for the mainline kernel. KVM requires hardware VT, of course.
The benefit of making that decision is that all of the other supporting pieces -- memory management, disk queues etc -- not to mention device drivers -- are all provided by the existing Linux kernel; virtual machines are treated as "just another process" by the host OS, but at the same time the performance hit of running inside a virtual machine is negligible.
So is Xen dead? As a commodity hypervisor, I think so. It will live on in specific places where it's highly customized.
Amazon EC2 is probably the best example; they've tuned the hell out of it and brought in some highly tweaked guest kernels so that they can fit a lot more guests on the same amount of hardware. That's the kind of place where Xen will continue to run. For the average IT/datacenter wonk doing server consolidation, it's all about KVM (and VMware) at this point.
By the way, ProxMox VE 2.0 finally came out of beta and was released last week. I haven't tried it yet but the screenshots look fabulous.
The way you put it, IG, it totally makes sense.
I got a question now myself:
I need to run two VMs (Linux Server (probably ClearOS) and definetly WinXP) on a server. Since it is mainly Windowsland out there, I need a way to manage (restart, etc) them via a webinterface or vnc/rdp. Also, there should be a desktopish non-network way to manage them directly at the host. There will be mouse/keyboard and tft attached.
The site were it runs is a commercial fascilty and they are the worst misers in the world, so should be totally FOSS. Any recommendations for the underlying OS (should be flavour of linux/bsd) and the virtualisation software?
(Is there a windows tool for libvirtd around yet?!)
Glad to see this is one of the few places I can actually see some true linux discussion and not some rampant fanboyism over Ubuntu and other garbage.
Fanboyism has its place but most of that type of thing came and went here years ago. Eventually you get to a point where you just want stuff to work.
Thankfully most Linux environments give you that nowadays. Manually configuring refresh rates in X11 and compiling features into your kernel are so 20th century.
So, I had to go online and found some awkward tutorial on how to configure it. That wasn't so bad, but the awful part was trying to get it to work with WEP/WPA/etc. For some reason I could just never get it to work properly so I got so frustrated with it that I configured the router to have no passwords and be locked by MAC Address.
I don't understand why the wlan0 would show up in iwconfig totally fine, but not in gnomes configuration utility and why would linux make it overly difficult to setup WEP/WPA from the command line?
First rule of WIFI under Linux: If it doesnt work out of the box, replace your WIFI card.
Second rule: Feck all the desktop specific gizmos and gadgets.
I use plain old wpa_supplicant, that is what is run under the hood probably by all other managers too.
And it actually has a gui and a tui: wpa_gui and wpa_cli.
my last fiddlings all have been about the RFKill and friends...
is the device up, is the radio enabled, is the whole card disabled by rfkill, sometimes rfkill even switches bluetooth & wifi with the same pushbutton cycling through them.
and... for shure... are the binary firmware packages installed.
OK, that was more interesting in my head. Carry on.
Subject: My experiences with virtualization
I used BBSes from 1982 - 1996 or so on Atari 8-bit and Atari ST. I was on here a few years back but the account had gone away. I listened to the fairly recent Security Now audiocast and decided to get back into Uncensored/Citadel. For my hobby and work email I've been running the OCS version of Zimbra for the last 5.5 years. I wasn't aware of the modernized Citadel when I got into Zimbra. I hope to use my own instance of Citadel at some point in the future. I'm a long time Red Hat (1996) fanboi and prefer RHEL/clone on servers and Fedora on desktops.
For virtualization, I prefer OpenVZ when it is appropriate for the task. Then comes KVM if the machine in question has VT in the CPU. If it is a 32-bit only system with no VT then VirtualBox.
The most OpenVZ containers I've had on a single machine is 1,000 but that was just testing. So far as containers that have actually been used... about 50 or so.
The most KVM VMs I've had on a single machine was about 40... all desktop Linux systems accessed via SPICE. That was for a sysadmin class.
oVirt is basically the upstream project for RHEV. I tried RHEV when it required Windows 2003 Server, IIS, and MS SQL server and Internet Explorer to run and use the management interface. Most of that changed in 3.0 and more is coming in 3.1. The design is too clunky and requires too much fancy hardware for me.
I like Proxmox VE but I'm not a Debian user. It seems kind of strange that PVE is based on Debian because Red Hat is king of KVM and OpenVZ bases their stable kernels on RHEL kernels. The PVE developers aren't familiar with rpm-based distros. Their choice of perl and not using libvirt was also fairly radical too... but I respect them for it.
I only have a few dozen VMs to worry about and don't really need any of the fancy features so vzctl and virt-manager work well enough for me. I'd love to see Proxmox VE made available for rpm-based distributions, based on libvirt, and support the SPICE protocol... but I won't hold my breath.
Scott Dowdle, Belgrade, MT
Subject: Re: My experiences with virtualization
From what I've read, SPICE is part of the PVE 2.X roadmap. I seem to recall they wanted it to be part of the 2.0 release but that definitely didn't make it in yet. I doubt we'll see an RPM-based version though; they've pretty much built the thing as a Debian spinoff.