Yet More Virtulization Questions

[DSapseid]

I am looking into the possiblity of replacing nearly all of our servers with nice new ones and virtualising most them all. I want to split each role that are currently on member servers onto their own virtual server.

 

I think i will leave the 2 DC's, SIMS, exchange and ISA servers as they are on physical machines and upgrade to 2008. Virtualise 2 File servers, Application server, etc and make each server only have one role as currently our Admin file server has 3 roles and its getting crucified speed wise! This will result in a possible 10 Virtual servers including 3 for terminal services as i want to do both projects at once.

 

I will also need a SAN for storage and backups with either a tape drive or removeable hdd for offsite backups. 4 of my servers are about 2 years old and the other 3 are really ancient and one is probably about 4/5 years old.

 

I just have a few questions and was wondering if anyone could answer them for me.

 

1. How many big servers will i need to virtualise 10 servers?

 

2. Can Virtual machines have 2 network cards with 2 different ips on as 3 of my servers currently do (on differnet networks)?

 

3. How big SAN will i need? My backups are currently about 500gb per night. Total HDD size on all servers is 890gb. i thought about 10/12tb.

 

4. Can i virtualise SIMS servers, DC's and exchange or is best to have those on there own physical boxes.

 

Hope that makes sense as i want to have all my facts straight for when i take the idea to SLT for the money!

 

Cheers

 

Dan

[tmcd35]

1. Two good spec servers, 8-core, 16Gb sort of thing. Maybe a third as a fail safe? Actually 10 VMs would probably work fine on 1 server at that spec!

 

2. Yep no problems at all - Atleast with VMWare which is all I've ever really used

 

3. At my last place we fitted a 2.5Tb SAN, seemed overkill for a school of 1800 puplils.

 

4. I've heard Exchange is best left physical. And from bitter experience with Bromcom, if SIMS is SQL baised it may be better left physical. I've Virtualised DC's in the past!

 

Hope that helps...

[DSapseid]

Yes SIMS is sql based so i will leave that physical. Any reccomendations for the 8 core?

[Theblacksheep]

There are a few here that run sims on VM as far as i know...

[tmcd35]

Alot depends on the VM software you want to run, the number of VM's being hosted and the shared storage (if any) the servers have access to. For 10 VM's I'd personally go for two servers connected to a NAS as shared storage area. I'd use ESXi which means any decent HP ProLient server will do just fine. I'd say single Quad Core Xeon with 8gb ram in each server, with room for a second Quad and more ram later. But that's all based on an idea from you saying 10 machines and may be over spec or underspec once we find out what job's each of the 10 VM's are doing.

 

My last place has two HP ProLient 8-Core with 16Gb Ram running of a SANMelody SAN with about 20ish machines running across them doing mostly file serving. A couple of web servers, DHCP, DNS, DC, etc.

[nicholab]

2.5 TB does not seem over kill for me I would be looking at about 4TB install.

 

We currently have 2.2 TB of data.

[DSapseid]

Vms will be the following:

 

File Server Admin

File Server Curriculum

3 x Terminal Services

Backup

Application (for network software Promissor etc)

Wiki

Anti Virus

WSUS

 

So the last 4 are not going to be hungry at all.

 

So would something like this with a second cpu and more RAM do the job?

 

I was looking at the Citrix Xen Server thing as i want the Citrix thin client as well so i was hoping that i could get some sort of deal i bought both at the same time.

[Theblacksheep]

So would something like this with a second cpu and more RAM do the job?

.

 

HP do the Blade version of the BL460 5440, if you get two, you'll get the c3000 enclosure for free. Get 4 and you get a c7000.

[tonyd]

I'm not sure I'd virtualise the terminal servers, from what I've heard performance is a major issue. Think of this in terms of running a virtualised enviroment within a virutalised environment, just like trying to run an emulator within another emulator you cannot exect it to perform as well as on native hardware.

[tmcd35]

Vms will be the following:

3 x Terminal Services

[\QUOTE]

 

Don't think, personally, Terminal Servers should be virtualised. When you think about it logically, TS is a form of Virtualisation. Running multiple desktops on 1 piece of hardware. So you are effectively virtualising a virtualised environment? I can't imagine the speed being too hot as 60 copies of M$ Word all fire up at the same time at he start of a lesson, or instance.

 

Backup

[\QUOTE]

 

Not sure of the wisdom of virtualising the backup server. At the last place it was. I'm looking at future VM options here and I admit it's one question I'm asking myself. If everything goes down where are the backups....

 

So would something like this with a second cpu and more RAM do the job?

 

Certainly the type of thing I'd look at. The last place used Tower versions of those, ML360's I think. Good, solid, reliable bits of kit and 100% ESX compatible to boot. Don't know about Xen, being Linux based I'll assume it's a lot less picky on Hardware.

 

If you're looking at Terminal Servers as well as VM's then TheBlackSheeps suggestion of Blades sounds interesting.

[DSapseid]

Yeh i had looked at blades. Where is doing the free chassis when you buy 2/4 servers?

 

I would be backing it up on to the SAN so it wouldnt need tape drive support.

[tmcd35]

I wouldn't normally think of the SAN as a back up medium. Unless you have two identical arrays mirrored on the SAN?

 

I'd, personally, look to back up VM's stored on the SAN to a portable NAS box perhaps once a term. Backing up VM's in this way should be no substitute to daily/weekly file based back up that should be running on the VM's themselves. Again I prefer portable NAS solutions for this - but you could use tape.

[Theblacksheep]

Yeh i had looked at blades. Where is doing the free chassis when you buy 2/4 servers?

 

HP Free Blade enclosure offer details

 

According to servers direct the offer has been extended through December too.

 

Free Blade Enclosure - Servers by Servers Direct

Edited November 20, 2008 by Theblacksheep

[sgreer]

Hi there.

 

1. How many big servers will i need to virtualise 10 servers?

 

It is entirely dependent on the load and function. There are products which help you determine things like this, such as Platespin - which calculates the resources your physical servers use and converts them into virtual resources.

 

There's no real taboo's with virtual servers because they are pretending to be physical servers, and they do a pretty good job of it. It is often argued that virtualising terminal servers is pointless which isn't necessarily true. If you are running a small scale (remote access for management staff, or 5 or 6 library users for instance) then you aren't going to max out a terminal server, and you get more from your resources by virtualising. Furthermore, even if you have load balanced terminal servers, although you're not likely to save on server resources, you will gain the other management benefits (HA, cloning, stopping, starting etc.)

 

I'd suggest a couple of quad core servers with plenty of memory as someone else mentioned, and possibly dual network cards. It would definitely be wise to perform some small tests to get a picture of the resources each of your servers use.

 

 

2. Can Virtual machines have 2 network cards with 2 different ips on as 3 of my servers currently do (on differnet networks)?

 

You can assign any network ports, physical or virtual to any virtual machine

 

3. How big SAN will i need? My backups are currently about 500gb per night. Total HDD size on all servers is 890gb. i thought about 10/12tb.

 

Using an offsite SAN via iSCSI is a good way of having a fail-safe, but it's a very expensive method of backing up.

 

4. Can i virtualise SIMS servers, DC's and exchange or is best to have those on there own physical boxes.

 

Yes abso-frickin-lutely. Domain controllers are the biggest waste of hardware going - bung all of them on a virtual server and moonwalk across the free floorspace ;-)

[EduTech]

There are a few here that run sims on VM as far as i know...

 

Yes i have SIMS on a VM, and it has run better then it has ever run before and much easier to back sims up too

 

We will be virtulising nearly all our server's the only ones that wont be will be storage servers.

 

But yh there is no reason why SIMS cannot be on a VM... our SMIS team also back us up on this as they do it for other schools. =]

 

Any questions where thats concerned feel free to PM me.

 

James.

[dhicks]

Domain controllers are the biggest waste of hardware going - bung all of them on a virtual server and moonwalk across the free floorspace ;-)

 

Are you saying this from experience or otherwise? I have a single domain controller running as a virtual machine, but I understood the advice from Microsoft was to avoid running multiple domain controllers as virtual machines as they could start to get confused if you started/stopped one and it got out of synch with the others.

 

--

David Hicks

[DMcCoy]

Are you saying this from experience or otherwise? I have a single domain controller running as a virtual machine, but I understood the advice from Microsoft was to avoid running multiple domain controllers as virtual machines as they could start to get confused if you started/stopped one and it got out of synch with the others.

 

--

David Hicks

 

Microsoft said a lot of things until they had a comparable product.

 

I've been using just 2 virtual DCs for 3 years now, no issues. All you have to do is avoid using snapshots etc with DCs and make sure they are kept in sync with an ntp server regularly. The same issues apply when using ghost images etc, as they can get out of sync when cloning and other similar activities.

 

Also don't build your vm infrastructure authentication around your virtualised DCs

[Butuz]

So you shouldn't use snapshots on DC's?? That's a shame as snapshots are great!

 

Butuz

[DMcCoy]

So you shouldn't use snapshots on DC's?? That's a shame as snapshots are great!

 

Butuz

 

If you revert A DC, it can have time stamps older than one of the other domain controllers. When this is detected it stops replicating and starts complaining.

[Ric_]

So you shouldn't use snapshots on DC's?? That's a shame as snapshots are great!

 

With virtualisation you can create a couple of DCs which are simply that and nothing else. In this instance it isn't necessary to snapsot that machine because you are unlikely to ever find yourself in the situation where you need to travel back in time.

[ChrisH]

I have no experience of DCs in a VM but I would also say that if your backup strategy involved backing up the whole VM file(s) then I would shut the machine down rather than pause it as well. Personally If I lose a DC and have a healthy one still running I will not restore from backup but rather create a new DC and let normal replication occur. This avoids problems highlighed above to do with syncronisation etc.