Best practice for a good Virtualized Datacenter Design - Part 1

In this post and other series of this title, I will review some great hints of a good datacenter virtualization design. But before anything, I want to ask you some major question:

1. What are the key components for an ideal virtual structure for different IT environments? 
2. How will you set up the virtual infrastructure?
3. And what elements are required for attending, before and after deployment and implementation phases?

In this post and other parts of this series, I want to deep dive into the details of good design for the virtual infrastructure based on VMware products.

In the first part, I investigated more about the basic requirements and prerequisites of IT infrastructures to migrate into virtualization. In other parts, I will review VMware's primary services and their impacts to achieve this goal.

1. Physical to Virtual

The first step is the estimation of the real needs of physical resources for the service providing. Processor Clock Rate (GHz), Memory & Disk Usage (GB) and also Network Transmission Rate (Gbps) must be calculated separately per each existing service and then we can talk about the required resources for the server virtualization. However, we should consider the hypervisor (ESXi host) overhead and add this measure to the total estimated count.

P2V migration always impacts to the service availability and usually needs to operationally downtime of the migrated service/OS. There are also some complexities in this manner, including:

1. Type of OS and supportability for converter application.
2. Specific Application dependencies via a hardware-locked.
3. Software Licensing problems.
4. SID/GUID changing issue for services like Active Directory.

So in the following, I provided a questionnaire about the P2V operation and you must answer to each of them carefully before the executing real migration:

1. Is it necessary to virtualize everything? And are you really sure about your answer? Why or why not, what’s the reason for keeping them into the physical area? or migrating to the virtual world… Answer of these questions is depended on your infrastructure requirement and you should reply it correctly for each of your important components and servers in your infrastructure.
2. Are you organized and prioritized each of the physical servers? Which ones must be on top of this list and which ones are good candidates for the pilot and test phase? I think selecting low-risk and non-critical workload servers is a good option for this state.

At last, you should provide a checklist like the following list to specify the server’s priority orders:

1. Application servers with low storage resources and simpler network and OS configuration.
2. Web servers with normal demand/request handling rate and also fewer dependencies to/from other servers
3. Network infrastructure services like VPN, DHCP, NPS
4. Mission-critical and organizational Application servers
5. Database servers based on SQL, Oracle and so on
6. Unified communication services like Mailbox, VoIP, IM servers.
7. Most important services in IT infrastructure like Directory services

 

2. Storage resources… How to provision?
If the physical server attached to a storage device/LUN/volume, there may be two difficulties exist:

1. Lack of enough space, if all mentioned storage used space must be migrated with the server to the new space provided by the hypervisor local storage
2. Access to the storage management system for zoning re-configuration and providing storage accessibility for the new deploying VM

On the other-side, in services with high critical transaction log files like Exchange server, migration of mailbox databases needs to consider the rate of the log space suddenly growth. Finally in every kind of P2V Migration, we need to more attention to temporary and permanent storage resources space.

3. Security consideration as the physical and traditional deployment

For choosing the virtualization platform, the selected solution must supply every security technologies that are deployed in the physical networking. It’s recommended that every aspect of physical switch security features like MAC learning, Private VLAN and so on can be supported by virtual switches. Distributed vSwitch technology used in the VMware vSphere platform is an ideal virtual networking solution for supporting many advanced security concepts like port mirroring and NetFlow. Except for VMware distributed switches (VDS), products of many vendors like Cisco, HP, IBM are supported by the vSphere networking platform. For example, Cisco Nexus 1000v is designed just as an integrated distributed vSwitch for the VMware platform. Of course, VDS design and migration from vSphere standard switch (VSS) to the VDS, requires to its implementation considerations (that I reviewed in this video playlist on my YouTube channel.)

4. Provide suitable physical resources for virtual infrastructure

One of the important characteristics of server virtualization in front of traditional server provisioning is the increasing rate of service availability and this requires the construction of VMware clustering. As a result, comply with the deployment prerequisites like employment of the same CPU generation and technologies in the ESXi members of the cluster is required.

It’s also recommended to use more similar physical servers instead of fewer servers with more physical resources. Thereby the Blade servers are a better choice as the hypervisor physical resources in front of other types of servers like the Tower servers.

5. Do not forget cleanup operation
After migration successfully has been done, you should start the post-migration operations, include checking the detected virtual hardware devices into the VM and also remove everything that is not required anymore on the new converted VM. For example in the windows guest OS you can run: devmgr_show_nonpresent_devices=1 and next run devmgmt.msc, then go to the view>show hidden devices and finally you can remove unnecessary or hidden items.
In the next part, I will talk about the power supply used for the computing and storage racks and how to calculate it.