Why virtualise

[garethEds]

Virtualisation - I know what it is - but why do I need to do it?

 

Why not just purchase servers?

 

What do you guys'n'gals use it for.

 

Cheers

 

GJE

[CyberNerd]

It's kinda handy being able to put 3 or 4 'servers' onto one physical box. Thats my main reason - we have lots of aging hardware that doesn't require epic resources. Do you need a dual xeon 4GB RAM for a file server - no!

 

There are plenty of other benefits, but thats my main concern

[webman]

Save space and power - instead of having 3 low-to-medium spec servers for example, just have one large server and run the 3 virtually to get the best out of the hardware.

 

Testing - create a whole virtual network on one server with multiple switches and servers.

 

Failover - hardware fails? Just move the server disk image onto another virtual server hardware and you're up and running again.

[ICTNUT]

For us we spent the best part of £30k, but these are the main reasons:

• Power Consumption drop by at leat 50%
  
• Heat output drops byat least 50%
  
• Being able to run 16+ servers on only 3 physical blades
  
• Furture proofing as we only have half our chasis filled
  
• Future proofing as our storage setup is only one shelf but we can goto 4 shelves providing 96Tb of data storage !!!
  
• all of our servers where out of warranty and needed replacing
  
• Short term big £££ layout
  
• medium to long term loads of £££ savings
  
• reduced maintenance
  
• reduced downtime
  

[tmcd35]

I think your questions probably been answered, certainly not got anything new to add. For me the big reason is disaster recovery. Virtual Machines are much easier to restore than physical server boxes. Space saving in the server room is a bonus - a quieter server room! Less power consumption. Also long term friendlier on the ol' budget. Only 2 or 3 servers to replace every 3 or 4 years rather than 9 or 10(+) servers being replaced on perhaps a 5(+) yearly rotation.

[mortstar]

It's the panacea to all I.T. ills.

[webman]

Just don't get carried away... put all your eggs in one basket, and if that basket fails, all your eggs are broken too.

[john]

True, thats why the setup we are making has a couple of seperate servers that will be DCs etc so we can keep mission critical stuff running if we have a blade system issue, these will be housed in a different rack in a different building as part of the DR Plan

[powdarrmonkey]

Sounds like you've got the right idea.

 

We virtualised for space and power mostly, but also for ease of provisioning. You need a server? Ok, give it five minutes to copy the image and you can have it. This way we keep roles as separate as possible so for example, a reboot of the deployment server doesn't include a reboot of user data.

[john]

Maybe worth having a watch of this - YouTube - VMware Infrastructure 3 demo very nice video.

[dhicks]

Virtualisation - I know what it is - but why do I need to do it? Why not just purchase servers?

 

Buying a larger server and Windows Server 2008 Enterprise/Datacentre is cheaper than buying four/more cheaper servers and single copies of Windows Server 2008 Standard.

 

You can give each server-based application its own server to mess around with, with whatever versions of whatever libraries it wants, and can have all the elbow room it wants.

 

You can take snapshot backups of entire server images.

 

You can change the amount of disk space allocated to a VM without necessarily having to add hardware.

 

You can buy pre-made VMs.

 

--

David Hicks

[AngryTechnician]

One thing I don't think has been covered so far is the ease of future hardware upgrades.

 

Want to migrate to faster hardware? Just copy the virtual server image over, and away you go.

[garethEds]

So I'm looking at what I could virtualise...

 

I have a nice twin quad core dell server sitting idle at the moment (alright, it isn't ide - it is running a RIS server).

 

I have a web server running as an assessment server.

 

I have a machine running as a WSUS server.

 

That's it really.

 

Could I virtualise the RIS server, the assessment server and the WSUS server on the dual quad core box?

 

I assume once you have virtualised your servers you keep backups of the images. Where do you store them? I also assume each image has it's own IP address - but does that cause a bottleneck on the network card on the machine?

 

Regards

 

GJE

[tmcd35]

We have virtualised practically everything across three physical servers. File servers, application servers, print servers, ghost server, and more besides. So far only our main DC has proved a little difficult to virtualise - needs rebuilding as a VM. The only other 'failure' we've had on the virtualisation front is our MIS. It was installed on a VM but the MS-SQL server doesn't seem to like being a VM so that is about to be moved to a physical server.

 

We also have two Terminal Servers which don't lend them selves well to being virtualised.

 

Yes each VM has it's own IP. We have two 1Gb NIC's teamed (giving a 2Gb pipe) for the VM's to share. So far I've not noticed any bottle necks here.

[garethEds]

We have virtualised practically everything across three physical servers. File servers, application servers, print servers, ghost server, and more besides. So far only our main DC has proved a little difficult to virtualise - needs rebuilding as a VM. The only other 'failure' we've had on the virtualisation front is our MIS. It was installed on a VM but the MS-SQL server doesn't seem to like being a VM so that is about to be moved to a physical server.

 

We also have two Terminal Servers which don't lend them selves well to being virtualised.

 

Yes each VM has it's own IP. We have two 1Gb NIC's teamed (giving a 2Gb pipe) for the VM's to share. So far I've not noticed any bottle necks here.

 

Yes, I have a print server that could be virtualised.

 

What products would you all advise that I look into? I know of VMWare - so is that the best one?

 

GJE

[dhicks]

I assume once you have virtualised your servers you keep backups of the images. Where do you store them?

 

Fire safe.

 

I also assume each image has it's own IP address - but does that cause a bottleneck on the network card on the machine?

 

You can assign a VM its own physical network card (or any other physical resource, like a disk or disk array).

 

What products would you all advise that I look into? I know of VMWare - so is that the best one?

 

We use Xen, running on CentOS 5.1 and using DRBD to mirror VMs around to provide real-time backup in case of hardware failure (see several previous posts on this subject!).

 

--

David Hicks

[dhicks]

So far only our main DC has proved a little difficult to virtualise - needs rebuilding as a VM.

 

Seemingly you can get confusion if you have more than one DC running - running as a VM causes time/date issues if you stop/restore the VM at any point. Probably fine if you only have one DC running.

 

It was installed on a VM but the MS-SQL server doesn't seem to like being a VM so that is about to be moved to a physical server.

 

Before you do - does assigning MS-SQL its own physical disk or (for preference) RAID disk array sort the problem? Some databases try to optimise their disk usage in various ways, and might get confused if they're using a VM disk image instead of a real, physical disk.

 

--

David Hicks

[powdarrmonkey]

We have virtualised practically everything across three physical servers. File servers, application servers, print servers, ghost server, and more besides. So far only our main DC has proved a little difficult to virtualise - needs rebuilding as a VM. The only other 'failure' we've had on the virtualisation front is our MIS. It was installed on a VM but the MS-SQL server doesn't seem to like being a VM so that is about to be moved to a physical server.

 

Odd, we've virtualised two domain controllers and 3 SQL servers without any problems, straight onto Xen.

[tmcd35]

We have two or three DC's virtualised but the PDC won't go. VM Convertor crashes out after at about 97%! And Ghost didn't work either. One of the machines problems is the Partitioning is odd to say the least (not my work!).

 

Theres a 10mb primary boot partition, followed by a 30Gb Logical drive that is also the System drive, followed by a 7Gb primary partition that is the C: drive. Never seen anything like it before!

 

As for SQL, I can't see what is wrong! Neither the physical server or the VM are reporting heavy usage - indeed processor are practically idling. The VM has 4 cores (two of which are dedicated to that VM) and 4Gb ram. Both Bromcom and my NM blame the slowness of some pages to respond on the fact that the server is a VM. Bromcom think that their is an incompatibility between MS-SQL and VMWare ESX. So the machine is being copied its own Physical box this half term. Personally I don't think it will solve the slowness problem - I think the speed issue is somewhere else.

 

Before you do - does assigning MS-SQL its own physical disk or (for preference) RAID disk array sort the problem? Some databases try to optimise their disk usage in various ways, and might get confused if they're using a VM disk image instead of a real, physical disk.

Yeah, we thought of this. The VM was originally hosted on our SAN. It was always running from it's own dedicated LUN on the SAN. But we thought this might be the bottle neck so we bought two SAS drive and put them in the physical ESX box (RAID-1) running the MIS. noticed only a slight speed gain from doing this. Everyone still blames VMWare for the speed issues.

Edited October 26, 2008 by tmcd35

[tbeach]

I have one question about vmware i can't work out in my head.

 

How do the clients connect join the dc?

Where do you run DHCP on the VM or the host?

How do you setup the VM network cards, as bridged or nat?

How do you connect other VM's to connect to that server again bridged or nat?

 

Many Thanks

[tmcd35]

It may help to think of the Physical Host server as a big kick-ass core switch and then each of the VM's are your servers connected to that switch.

[tbeach]

So do i assign a ip address to the host. Then the VM is then bridged which will have its own IP address and it will be running DHCP - DNS - AD. Would this be the correct way of doing things?

[powdarrmonkey]

Yes. All the servers are assigned resources so that they look just like a whole machine to themselves. They behave exactly as they would in the real world in terms of connecting to other nodes. Think of it like amalgamating many kettles into one big water boiler.

[garethEds]

SO let's say I decide to virtualise my WSUS server. Am I better creating it from scratch (I can do that at home and transfer it to school), or trying to virtualise my current server (which I would have to do in work).

 

What product would you recommend?

 

GJE

[powdarrmonkey]

I only have experience in Xen, for which the process (if you don't want to start from scratch, which would be better) is:

 

1. Boot off Xen disk and tell it to convert the current machine to a virtual

2. Xen will install itself as a virtual machine domain with one virtual guest, the original machine

3. Export the virtual machine and import it to its permanent home

4. Configure it in Xen (allocate network etc), boot it, and configure it appropriately.