Windows plays virtualization catch up with Linux Linux server users are reaping the benefits of virtualization more than those running Windows. Microsoft's restrictive and confusing licenses are a big reason for holding back Windows customerson virtualization. The company's foot-dragging on VMware and Xen support, plus Hyper-V's relative lateness and immaturity, are also …
Virtualisation = Water
The two just don't mix. I've virtualised lots of bsd and linux servers with great success.
Firstly, for most applications, you just don't require multi gigabytes of RAM just to get the basic server up and running as you do on Windows. Oftentimes you can get away with a few hundred megabytes. This is great when you have a bog average server with 2-4 gigs of RAM, all of a sudden you can stick a dozen instances of a *nix server on a 1U server without trouble.
Want a server that does nothing but serve up a few static web pages for a low volume domain?
With Windows, you have to worry about licencing, it costs how much?, I have to wait 90 days? (wtf is that crap btw), pay for 8 cpus? but I only want to assign it 1! etc etc. Then of course there is the whole "needs 2GB just to run" thing even before we start loading apps on it. All of a sudden you find the PHB is pressuring you into saving on costs by running SQL Server and Exchange on the same machine because otherwise you would be wasting all the above resources yada yada yada
On the other hand I can install a targetted build of freebsd in a VM, assign it 256Mb and do the same with separate servers for postgre and postfix while using less than half the resources and all at ZERO COST with plenty of virtual room left for other stuff!
Why on earth would you bother going the Windows route?
I think the licensing issue for MS users should now largely have disappeared due to the increased performance per physical host now available.
WIth a dual socket 54xx or 55xx Intel server it is now more cost effective to buy Windows Datacenter licences than Standard or Enterprise. This licence allows unlimited virtual instances and has made a huge difference for us at least.
I don't really get the point. Isn't it easier and cheaper simply to run several functions on a single server (or cluster), rather than splitting it into to several virtual servers? Every server (virtual or otherwise) needs some systems management, O/S licensing, certificates, etc. - and the server performing the virtualisation needs management as well - including the virtual network components, cluster distribution and so on.
Virtualising is more about having tighter control, at least that's how I see it. A memory leak in an application on one VM isn't going to affect other VMs, likewise a root exploit on one VM won't give someone access to the things running on other VMs. Also, it's simpler (imo) to allocate resources to a VM (disk, ram) then tweaking settings for various daemons. There are other advantages, such as being able to have different network settings on different VMs (tcp windows, mtu's etc)
For those that do not understand what virtualisation brings.
When you install several servers on the same physical machine, using the same physical services, you have the possibility of customers accidentally accessing other customer's data. No matter how secure you set up your server, there is always the possibility that the customers make a mistake and create the possibiility of others seeing their data.
By creating virtual instances of servers, you create one server per customer, yes it does consume some extra resources, such as memory, and also requires similar management to a full server, however, there is an absolute seperation of the servers, which means that even if the customer messes up internal security features, such as file permissions, then there is no chance that another customer can gain access to those data.
Now the virtual bit, just means that you can host multiple servers on the same physical hardware, with the same security that seperate physical machines would achieve.
Another benefit by virtualisation is that because each virtual server, in principle, is just a file on the server, moving the instance to another bit of hardware, just means moving that file to another physical piece of hardware, and boot the virtual instance, and wupti you're online after a server hardware crash.
Also if you have a physical server with a lot of virtual servers on it, and your cpu usage is reaching critical levels, you can always move one or more of the vritual servers to other physical servers, and thus distribute the system load very simply, without having to reinstall, or move applications, between servers.
Systems that lend them selves to efficient virtualisation are those that do not carry tonnes of redundant active services with them, eg a linux server stripped down to a web server, would consume less than 128MB of memory, depending on the complexity of the web services provided.
Other systems that have a lot of things that cannot be removed from them, tend to waste more resources, and therefore are less efficient when virtualising them. I would class Windows as such a system, because I've yet to find a way to strip windows down, so that it does not consume around 512Mb - 1 GB to run properly. However, your milage may vary. Considering how many virtual linux servers there are, compared to windows, may indicate that I'm not completely wrong.
There's the human factor. No sysadmin wants to partake in developer squabbles. Dev A: "we have to upgrade - I need new feature X" Dev B: "no no - that's the version where they remove all the deprecated methods I'm using - we can't upgrade!" Just give them their own server and everybody's happy.
VMware has some nifty downtime mitigation tools. If you need to upgrade a hardware component, or replace a server, you can "vmotion" your virtual machines to another VMware server with no downtime.
There's other features too - the popularity of virtualization is definitely due to more than just people being suckers for marketing.
in my opinion vmware isn't much better than windows
tell me why I have to buy a windows license to get to my virtual machines server console?
and vmware esx server runs on linux so don't worry microsoft has their hand in everything and they are making sure they get a share of something vmware makes.
when citrix bought xen it really gave microsoft time to catch up to linux. citrix is a preferred partner of microsoft and IMO just another department of microsoft.
luckily there is kvm for Linux and that is really taking off now and also was around when xen was taking off but now the hardware is getting more pervasive for kvm and so that is really the way to go.
let's just hope microsoft doesn't put the squeeze on Intel and ruin the hardware virtualization market somehow.
but microsoft is obfuscating the virtual server industry just so they can catch up.
they have done this hundreds of times before and are doing it again.
but hey if you have a business model and paid lobbyists living in Washington it is all good.
On a unix machine it is relatively easy (and common) to install several functions on a single system, you can even install multiple instances of the same application in many cases either by installing to different prefixes, or using chroot. And there are also the lighter weight virtualization options based on souped up chroot (eg openvz).
On windows however, it's generally recommended not to run multiple functions on a single box (and problems are likely to occur if you do), and often impossible to run multiple instances of the same application on a single box.
"Every server (virtual or otherwise) needs some systems management, O/S licensing, certificates, etc."
Licensing is a moot point with linux, you are entitled to install it on as many servers (virtual or otherwise) as you want...
Also, by having lots of small single purpose machines instead of a small number of big multi purpose machines, you can actually decrease maintenance significantly... Each server has the minimum required applications installed on it meaning you have less to update and less to test, and you can update your services one at a time with no risk of breaking other services.
Another benefit of virtualization is that each server is inside its own container, and can be shuffled around different physical servers at will, making it easier to upgrade hardware, easier to replace failed hardware, easier to make backups etc
There are also the security aspects, if you find a security hole in a single service and gain access to a server you now have the potential to take control of other services running there that individually would have been secure.
leaving the debate about the benefits of virtualization aside (and if those numbers are to be believed, then virtualization is now a fact, not an idea) this is not the first time microsoft has been late to the party and although VMware has a huge lead on Hyper-V at this point in time, microsoft will catch up. Its up to VMware to use their lead to continue to be pioneers and keep pushing the boundaries. but at least having Microsoft yapping at their heals will benefit us all by getting VMware to drop those high prices of theirs.
I don't understand people who complain about having to run Windows on a single hardware installation for 90 days. Microsoft has *no way* of finding out if you've migrated a VM from one host to another. My company has reaped huge advantages from virtualizing Windows, so I guess we're one of the outliers.
As far as understanding the benefits: if you don't understand, you've never used virtualization.
I really don't see this, where I work any new Wintel server is automatically virtual, unless there is a requirement for it to be physical (large SQL clusters, backup servers etc, would be physical) we are moving our desktops (XP) to virtual, currently we've got 4000 over to VMs and in the next month or so it will be 22000. Eventually all our desktops (well in excess of 1000000) will be virtual. By comparison all of our linux servers are being put onto HP blade hardware, with very few virtualised.
I realise this is a single example, but it does go along side my pervious company (who were rather smaller) who are doing the same sort of thing.
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