The Old Joel on Software Forum: Part 4 (of 5) - Why the use of vitualization software?

Why the use of vitualization software?

There is an interesting article in the NY Times on IBM's server strategy : http://www.nytimes.com/2004/04/28/technology/28blue.html

One part of the article commented that Mainframes commonly use virtualization software to run 10 or more operating systems.

Why would there be a need to use virtualization software to run multiple OS's on a server or mainframe?

I use to think virtualised OS platforms were used for testing only and are not inherently stable.

Don Quixote
Wednesday, April 28, 2004

>Why would there be a need to use virtualization software to run multiple OS's on a server or mainframe?

Certain software will only run on X platform? Or runs better/faster/cheaper on Y platform?

>I use to think virtualised OS platforms were used for testing only and are not inherently stable.

Nope, at my employer (small IT consulting shop) we run production servers on a monster virtual server (x86) - 4 CPU, 6GB RAM machine. VM's for SQL Server, Exchange, CRM, Sharepoint, Domino, Domain Controller, etc...

We also have a development VM server with a similar setup...

...
Wednesday, April 28, 2004

Fascinating!

A single box, emulating whatever processes necessary to provide the environment(s) and tools to accomplish the task. No more OS wars, or personal attachments. Its like a Swiss-Army PC. A holodeck for computing.

"The future has arrived."

sedwo
Wednesday, April 28, 2004

There are two parts to the answer
1, Why have your web server, email, database and accounts packages on separate machines ?
A fault / hack on one doesn't affect the others, a security patch needed for the web server doesn't have to be tested for the database, you can upgrade one without loosing all the others.

2, Why use one machine + virtual os instead of 4 machines?
A single 4cpu machine is cheaper than 4x1cpu, they share expensive peripherals like raid arrays and tape drives, they save space in a server room.
Also you can usually dynamically load balance, if the database occaisionally needs lots of CPU it can be temporarily given more slices instead of having to build 4 machines all spec'ed for the worst case.

If you need to move one of the apps off to it's own machine you just move the virtual os image over to a new virtual os, don't have to reinstall or configure for new hardware.

Martin Beckett
Wednesday, April 28, 2004

Besides heterogenous platforms, there's also the issue of running multiple servers; there are processes that, whether by design or for security reasons, shouldn't be run on the same box (email, web, and database servers, for example).

So in the past companies were faced with buying three or four boxes just for a basic internet setup - $10k+ worth of hardware that will run at 5% CPU usage...

Virtual servers mean you can buy just one box and run all the systems you need. Buy another box and create both your test and dev environments on a second box.

Philo

Philo
Wednesday, April 28, 2004

Awww... Martin beat me to it...

Philo

Philo
Wednesday, April 28, 2004

"A single 4cpu machine is cheaper than 4x1cpu, they share expensive peripherals like raid arrays and tape drives, they save space in a server room. "

It depends. 1x4 is a hell of a lot more expensive than 2x2.

Just me (Sir to you)
Wednesday, April 28, 2004

"I use to think virtualised OS platforms were used for testing only and are not inherently stable."

On mainframes, virtualisation is how it is done and it's completely stable. I've never seen a mainframe that didn't run a number of OS's (and/or the same OS a couple of times).

Almost Anonymous
Wednesday, April 28, 2004

Also, if you want to reduce the number of different system types and the number of admins, you stick it all on one box.

Often times, for historical reasons, you'd have two or three different IBM mainframe OSes -- VM/CMS, TPF, and MVS -- for different roles and they were formerly on individual mainframes, plus some Unix machines here and there. The goal is to stuff them all on the same machine, which is entirely possible on a zSeries (a.k.a. S/390) mainframe.

I think the key thing is that there are advantages to a small number of large machines and a large number of small machines, plus all of the points between. And there's lots of money to be made helping people move on this axis, and there's lots of prestige to be made by suggesting that it would be better to be at a different point on this axis and being at least partially right.

Flamebait Sr.
Wednesday, April 28, 2004

Actually I'm using a virtual hosting service from rose hosting. It isn't as sophisticated as IBM's solution, but the concept is similar. I personally think it is the future. It is cheap and it works.

I am running two seperate virtual servers, primarily for security reasons, and find it is a great compromise.

christopher baus (www.baus.net)
Wednesday, April 28, 2004

i think you need that machine so you can run spell checker faster and not write vitualization instead of virtualization :)

Wednesday, April 28, 2004

Some more reading material:

http://docs.freebsd.org/44doc/papers/jail/jail.html

Tom H
Wednesday, April 28, 2004

==>"The future has arrived."

Boy, you're new to this aren't you? <grin>

I worked for IBM in the 94/95 time period -- a decade ago. I worked on PCs at the time, but occasionally had to dabble on the mainframe. Similar technology existed at that time, 10 years ago.

Virtual servers were available with Win 2K (Datacenter version)-- I went to a preview seminar in 1999 (I think) that had a demo of this functionality.

Folks at my shop have been using VMWare for at least the last 4 years, and Virtual PC for the last year or so.

None of this is new.

Hell, back in my IBM days, we used OS2 with a (sort of) "Virtual Windows" -- where we could run windows 3.1 and apps in a virtual windows environment on the OS2 boxes. Again, about a decade ago.

None of this is new stuff, it's just getting more and more popular.

Sgt. Sausage
Wednesday, April 28, 2004

Huh huh. Virtual PC rules, Beavis... and being included in the Action Pack, the price is certainly right.

Virtualization has been around in PCs since the 386. I think the burst of interest in this technology is due to CPUs, memory, and hard drives that are finally able to accommodate the virtualization overhead and the need for multi gigabyte virtual partitions. Without proper hardware and memory, virtualization seems like it would be pretty lame.

Windows 3.0 was the first consumer OS to allow virtualization of multiple DOS real mode sessions. Granted, it was somewhat unstable and feeble virtualization, but it allowed you to do smartassed and amusing things like enter FORMAT C: from a command windows in a retail store, minimize the window, and walk away nonchalantly while DOS chomped away at the file system underneath Windows... heh...

I've installed Red Hat in one VPC partition, and Windows 2000 server in another. The W2K partition (running underneath XP as the 'host' OS on a 2500mhz cpu) feels like it is running on a 1 ghz cpu. Not a speed demon but respectable.

It's a fantastic tool for learning and admin training. In fact, I have even opened up my firewall and had the Red Hat instance serve pages with Apache.

Bored Bystander
Wednesday, April 28, 2004