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Hyper-V Correct Usage of VMs and VHDs

Posted on 2010-11-12
Medium Priority
Last Modified: 2012-05-10
I want to change out some physcal servers and begin running Hyper-V.  However, I am trying to figure out some configuration issues.

Currently I have the following accessed by about 50 users:

Fileserver - currently has 2 shares (DocMgmt and Data)
The Data share is the main network drive mapped on the client PCs.  Stuff like user directories are stored on it.  However, some workgroup applications are installed to that drive from client machines and are executed from this share or houses data from the client piece of the program.
The DocMgmt share houses a ton of documents that are saved by our document management software program.  When the uses saves/profiles a document, the file gets saved here, and the file data/profile gets saved to the SQL server.

SQL - has the database for our Document Management solution and our accounting system.

Exchange - typical exchange install

I am adding:
2ea - DL385 G7 2-processor servers, Windows Server 2008 R2, 40GB RAM, 2ea - 146GB SAS 15K HD (2 for each server, mirrored)
1ea - SAN P2000 G3 SAS Dual Controller Array, 8ea - 300GB SAS 15K HDs
4ea - SAS Controllers (2 for each server for redundant connectivity to the P2000)
2ea - Microsoft Windows Server 2008 R2 64-bit Enterprise
Microsoft Exchange 2010
Sql Server 2008 R2

My goal is to use Hyper-V to recreate and host a VM for each of my previous mentioned servers (Fileserver, Mailserver, SQLServer).  Then to have Hyper-Vs High Availability configured to switch between my 2 servers if anything fails.  Of course hosting the VMs or VHDs on the SAN so that both servers can access them.

What is the best way to configure my drives in the SAN for this scenario?
Should I create a VM for my fileserver but have seperate VHDs for my 2 shares?  Or just make my OS and all shares just on one big static size VM file?
Should my drive for SQL be paritioned to segment logs and other items?
The SAN will also be used for another share in the near future as we start a paperless initiative.

As you can see, I have not too much experience with Virtualization (or SANs for that matter) but am ready to attack.  Any suggestions or ideas are welcomed!!

Question by:lbjennings
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LVL 14

Accepted Solution

Schnell Solutions earned 1000 total points
ID: 34125954

In case of using Hyper V with High Availability it will be recommendable that you use your VM files in a shared network, and the VHDs in yhe SAN

The ideal configuration is tu use at least one LUN per VM. Of course this is an expensive solution, but the one with best performance and efficiency

There are some applications that will have many benefits when using different LUNs inside the same server. For example exchange shall have a disk for the LOGs, another one for the DBs, another one for the paging file and queue files, etc. But we always need to balance the cost vs the benefits that this solutions offer

There are some advantages of separating disks. We mitigate the fragmentation issues, we have the option and possibility to separate the VHDs to different LUNs. THe common drawback of this option is the administrative effort of handling many VHDs

The fixed size disks are better with performance because they don't change their size and they are less affected by defragmentation in the host disk but they are difficult to transport and move from one place to another because they took the entire size

If the SAN will be shared for antoher services. It is recommendable the the LUNs used for Hyper-V be independent from the rest of the services. (Separate disks, not shared, into the same SAN)
LVL 42

Assisted Solution

kevinhsieh earned 1000 total points
ID: 34125956
I am not familiar with the HP line, but it looks like your particular model only allows SAS connections. Clustering Hyper-V should be supported, but you can only connect 2 hosts with dual controllers, and none of your VMs can natively connect. My suggestion is to go iSCSI if you haven't already bought the equipment. iSCSI would allow you to connect more servers, and they can be physical or virtual. There are real advantages to connecting your file servers, SQL server, and Exchange servers to your SAN via iSCSI. The advantages are that you can dynamically grow storage and take advantage of SAN integration with your backup software.

As far as how to use VHDs, for your SQL, Exchange, and file servers I would put the OS on its own VHD. Data files should go onto 1 or more separate VHDs or directly onto the SAN. Separate VHDs and/or storing directly on the SAN makes management, backup, and recovery easier. I once had my Windows 2003 file server die, and I couldn't get it working again. Since all of my data was on the SAN, I was able to attach another file server to those SAN volumes and bring my shares back online pretty quickly. If I had to actually copy the data to another machine it would have taken a day just to do the copying. Separate VHD for your database logs and data won't improve performance because everything goes back to the same physical disks, but it's good practice and won't cause any problems.

I make my VHDs dynamic, and I set them to a reasonable size, like 30 GB for the OS. Performance is almost the same as a fixed VHD (with about 2%), and it's easier to deal with smaller files. If the VHD needs to be bigger, you can grow it after you shut down the VM. If you use iSCSI in the guest to connect to your SAN, you can dynamically grow the volume online, which you can't do if you are using VHD. That said, a VHD is very easy to backup (just shut down the VM).
LVL 74

Expert Comment

by:Glen Knight
ID: 34824856
This question has been classified as abandoned and is being closed as part of the Cleanup Program. See my comment at the end of the question for more details.

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