Server Virtualization

[Buffy]

Virtual Servers are all the rage now--yes in Windowsland, down boys, I'll beat you up on your fave platform in a minute.

 

"What's that?" You ask? Short answer: You're an IT department with a limited budget. You endlessly have user departments coming to you saying "we need our own server!" But you can't afford more hardware, and top management is wondering why the servers you do have are barely used (well, some of them anyway). Virtual Servers to the rescue! Load one of these puppies on your favorite PC compatable and voila! 2, 3, 4 or more servers where there was formerly only one! Whoa!

 

The space was pioneered by a company called VMWare (which got started with software that emulated IBM 370 Mainframes on PCs of all the wacky things), and Microsoft even has their own now.

 

This little thread is to discuss the ups and downs of such solutions. Have you ever run them? What do you like about them? What's sucky?

 

Now I see you Linux biggots sitting there smirking, "we don't need no steeeenking Virtual Servers! We're already cheap!" Yeah, we know you're cheap... BUT Novell/SuSe, Verio and others all have been rolling out Linux Virtual Servers. So, yes, it applies to you too! :phones:

 

Virtually free,

Buffy

[Boerseun]

I was deeply involved in a project that virtualised the server infrastructure for one of the biggest commercial banks in SA. That was about two years ago. The impression I got from it was that it serves mainly to cater for legacy software in the company that refers and maps to individual servers, where powerful new hardware can cater for the needs of quite a few machines. We ran on average about five virtual servers to a machine, and the bank had about sixty servers at its head office in Johannesburg that we virtualised.

 

There are quite a few downs to it, a hardware issue before would have taken out only one server. Hardware issues now will take out whole departments. So it's quite important how to distribute your servers! Say, have only one mission-critical virtual server per physical server. Better yet, don't virtualise mission-critical servers! Also, virtualising two servers on one kick-*** platform effectively halves the performance of the hardware you're doing it on. So, once again, if you have servers doing a lot of intensive number-crunching or one that has a lot of network traffic flow, better not to virtualise.

 

But all in all I was quite impressed with it; it served its purpose. There are instances where virtualisation works a charm, but then there are also situations where you should avoid it like the plague. It depends on the specific circumstances, I suppose.

[Buffy]

My sense is also that load balancing can be nightmarish: user think they have their own server and they are colocated with a server that has wide swings in usage.

 

Anyone know anything about "dynamic virtualization" that uses completely distributed processing? Google supposedly has done some work in this area and old timers will remember Plan 9 which had some pretty grandiose ideas about distributed operating system design...

 

Distributing your cares away,

Buffy

[Boerseun]

I think a better idea to get away from the fact that you're concentrating your hardware into single points of failure is to build two seperate but identical and equally powerful (obviously) machines, and mirror them. They'd both be running RAID5, for instance, with both RAIDs mirrored. Ideally, they'd run from different UPS's as well. Then you can virtualise to your heart's content, if a hardware plaform croaks, the other machine will run. Then you simply fix the broken hardware, plug it back in and have the mirror fix itself. And the users won't be any the wiser. As far as I know, both VMware and MS Virtual Server caters for this. A tad expensive, though; depends on how secure you want the environment to be.

 

If you've started this thread 'cause you have to sell the concept to a client (gotcha! :) ), it's quite an easy sell. You don't need expensive knowledge to implement this, it's quite easy, really. A few years ago when this came out, Microsoft sent some of their really expensive wizzkids over to come help us; it ended up in us showing them how their own product worked. We basically installed and implemented it throughout the environment with the M$ guys in the background saying stuff like "Cool!" and "Awesome!". They still billed us for it, of course. But we started from a zero knowledge base on it, and it is still running fine to this day. If you take the package home on Friday and play around with it, you'll be an M$-beating boff by Monday. Guaranteed.

[Buffy]

If you've started this thread 'cause you have to sell the concept to a client (gotcha! :) ), it's quite an easy sell....

Actually no, its because we have customers that insist that our software run on it. I've blythely said, "sure no problem!" And it sure seems to work at the two customers who are running it (both VMWare), but of course I'm wondering if there are any gotchas....

 

Blissfully ignorant,

Buffy

[Boerseun]

If its a done deal and the environment is already installed, you shouldn't have too much to worry about. Remember, one of the key ideas behind server virtualization is to cater for legacy software pointing to individual servers. Legacy software is normally old stuff that wasn't built to cater for newfangled server/hardware concepts. So, in order to make that possible, both VMware and MS Virtual Server was written in order to bullshit the software to believe that its running on its own individual unique machine.

 

The fact that there are several 'machines' running on the same hardware is completely invisible to the software. Unless you're into some serious number-crunching; a multiprocessor machine can dedicate individual processors to individual 'servers', but allocating all available processors to one specific server for a fraction of a second makes all the other servers on that machine hang for that part of a second, until the processor gets around to them. So, using multiprocessor is fine, but then every 'server' will only get the performance of a single processor machine. A fine balancing act, really, if you want all your 'servers' to run 100% of the time. A small fraction of a second doesn't sound like much, but the switching over to the next 'server' takes time, and it builds up noticeably if they're all under load.

 

But I don't think you have any software issues to worry about. What are the dependencies? We virtualised servers running software from ages gone, and it ran 100% without tweaking any of the software packages at all! :)

A rule of thumb that we used, if your software will run on the hardware without being virtualised, it will run as a virtual server, too, seeing as all the Virtual Server does is simply to provide a blank, driverless copy of the hardware to a new partition where you've gotta install a fresh OS.

[Buffy]

That's always been my assumption. We've got a vanilla ASP/SQLServer app that's fairly modern (no "ancient"--pre 2000--software required), so its hardly something I really had any concerns about. BUT you should have heard the grilling I got from these IT types: "Are you *sure* it will run on VMWare?" "Have you certified it?" "How many sites do you have it running on in virtual environments."

 

Of course, that's the kind of garbage that IT types get paid for--no offense B!--but they sounded positively paranoid, like they'd had lots of bad experiences...

 

It just goes to show you there's always something, :)

Buffy

[Boerseun]

Of course, that's the kind of garbage that IT types get paid for--no offense B!--but they sounded positively paranoid, like they'd had lots of bad experiences...

None taken - that's one of the reasons I quit the industry completely and did a complete career change into advertising! :)

[Killean]

Some of the Hypography sites were being hosted on a centOS virtual server. It gave us the feeling of having full root control over the server, yet we had the standard problems of being on a shared server. I'm spoiled though, I prefer pure dedication to my needs. :thumbs_up

[alexander]

Hey Buffy, i have no idea as to what your point inclanation is in that very first post? Are you saying that Windows is the only OS providing server virtualization software?

 

There are hundreds of companies that have been working on this, not the least of them Microsoft, Suse or Google. Vmware has great products, but then again they are all available for Linux, so i see no reason as to why you would raise this "Great Windooze" whopty-doo thing.

 

There are loads of available products waiting to become a solution for someone, and most run on linux and most suppor windows and most do load balancing... It all depends on what you want to use it for...

[Buffy]

Hey Buffy, i have no idea as to what your point inclanation is in that very first post? Are you saying that Windows is the only OS providing server virtualization software?

Naw! I'm not that much of a rube! I was giving you Linux heads a hard time because there's this meme about things that Windows has aren't *needed* in Linux land.... :eek:

 

Just looking for random thoughts and experiences, although my main interest was about what B and I talked about above which is the issue of compatibility of apps that run on windows vs. running on virtualized windows...

 

greping since before you were born,

Buffy

[C1ay]

Now I see you Linux biggots sitting there smirking, "we don't need no steeeenking Virtual Servers! We're already cheap!" Yeah, we know you're cheap... BUT Novell/SuSe, Verio and others all have been rolling out Linux Virtual Servers. So, yes, it applies to you too! :eek:

 

Actually virtualization became part of the Linux kernel with 2.6.20 :) How long do you reckon it'll be before Micro$oft builds it into their kernel......if ever? :hihi:

[Buffy]

Actually virtualization became part of the Linux kernel with 2.6.20 :hihi: How long do you reckon it'll be before Micro$oft builds it into their kernel......if ever? :eek:

 

The idiots in product marketing (I can say that because I am one from time to time), think it will encourage software piracy. On the other hand, they decided to make it *free* in order to try to put VMWare out of business, but I don't know anyone who's using the MSVS, do you? VMWare is everywhere....

 

We can make more money and annoy our users at the same time,

Buffy

[C1ay]

but I don't know anyone who's using the MSVS, do you? VMWare is everywhere....

 

Then again I wouldn't even compare MSVS with Linux virtualization. MSVS is a flawed resource hog. It no wonder it has low market penetration compared to VMWare in Windows shops...

[pmaust]

We old IBM Mainframe guys have been doing virtualization for decades. :shrug: I can run hundreds of Linux instances on my machine and still have a mainframe operating system running in a different LPAR. Glad to see the micro world finally catching up a little. :cheer:

[Buffy]

Of course! Gimme a bigger "minidisk" please!

 

COBOLectomy,

Buffy

[pmaust]

Of course! Gimme a bigger "minidisk" please!

 

COBOLectomy,

Buffy

 

No problem. You can have all the minidisks you like. You can share the SAN and virtual tape as well. Throw in a little Microfocus and .NET running on Linux. It's all good. :shrug:

 

C++ya,

 

Paul