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Virtualization Basics and the different types of Virtualization

Posted by decipherinfosys on February 12, 2009

A lot has been said and written about virtualization and a lot of companies are finding benefits adopting it in their IT infrastructure or the data centers that they might be hosting their applications with.  At Decipher, we have been supporting our clients with their virtualization needs specifically with the VMWare and Hyper-V solutions and have also blogged about it before.  Recently, while making a presentation to a potential client, one of the questions that was asked by the Operations Manager was to give a brief overview of virtualization and the different types of virtualization.  We are sharing that with our readers as well here.

Basically, virtualization is dis-associating the tight bond between software and hardware.  In a traditional world, one would use one server for their Oracle instance, one for a Microsoft instance, yet another one to host their Exchange Server and so on for the other applications that they have to support.  At times, you would be able to consolidate them assuming that the OS, providers and the different vendor requirements are common.  What this ends up doing is give you a tons of servers to manage, which consume more power, waste the resources on these boxes because some of these servers would be under-utilized (CPU, Memory wise).  Not only that, if you need to add more capacity you would either try to scale up (more memory or additional processors if possible) or scale out (more servers).  By being able to dis-associate the bond between the software and the hardware one can then use the same hardware to serve up the needs of the different software servers.  So, you could be running Oracle, MS SQL Server, Exchange, Great Plans, Dynamics CRM, etc. all on the same hardware.  By doing this, it is also possible to run different operating systems so I could run MS SQL Server 2008 on Windows 2008 Server and at the same time run, Oracle on Linux all running on the same hardware.  By doing this, the resources will be better utilized and also allow us to easy add another VM on the same hardware assuming that we have the capacity.  There are additional benefits as well like making use of the vmotion capabilities of VMWare etc..

So, that was a 50,000 ft. overview of virtualization.  So, how does it really work?  What breaks the bond between the software and the hardware?  We are going to talk only about VMWare’s ESX Server 3.5 and MSFT’s Hyper-V since the older offerings from both these vendors had a different architecture.  Both of these are based off hypervisor based architecture.   A hypervisor which is also sometimes called a VMM (Virtual Machine Monitor) is essentially a hardware platform virtualization software using which one can run different OS on the same hardware at the same time.  Hypervisor has access to the physical host hardware.  Even though both Microsoft’s solution as well as the VMWare solution are based on the same hypervisor based technology, there are differences in how the implementation is done.  We won’t cover all those differences here but will provide some links

Now, what are the different types of virtualization available and what are the dominant players in the market that provide a solution for it.  There are essentially three different types:

1) Hardware Virtualization:

This is the most common and is used in IT departments in a company as well as in the data centers.  The server’s hardware is virtualized thus allowing us to be able to run different OS and different applications simultaneously on the same hardware.  This allows us to do server consolidation.  And the benefits are obvious (only listing the critical ones here…and less cost is a major advantage across all of these):

a) Less number of servers required for the same number of applications.
b) Less power consumption.
c) Less maintenance overhead for the IT staff.
d) More resource utilization.
e) Easier (and faster) to add more capacity.
f)  Patch management and upgrades become easier.
g) DRP (Disaster Recovery Planning) becomes easier.  Without any interruption to the service, one can backup and even migrate entire virtual environments.

2) Desktop Virtualization:

We have gotten into the habit of calling this VDI since that is the term that VMWare uses for desktop virtualization.  VDI stands for virtual desktop infrastructure.  But this is not limited to just VMWare.  Citrix systems has a similar offering called the XenDesktop.  What this means is that your end user’s computer’s data – their OS, their applications, their downloads, their preferences etc. are all stored in a VM in a hosted environment which could be hosted either by the company’s IT in-house or hosted in a data center.  Som the VMs are then managed in one single place for all the users in a department/company and the computing environment is delivered remotely to the end users.  The one reason why the adoption has been a bit slow on this front is because unlike server consolidation (hardware virtualization), desktop virtualization requires working across a lot of different organizations within the company and it impacts the end users a lot more during the stages of putting the plan in place and executing it.  Benefits are obvious:

1) Easier upgrades and patch management.
2) IT Desktop support process becomes much more easier.
3) You can easily add more users as your organization grows and provisioning of new applications and VMs takes minutes and not days/weeks.
4) Better resource utilization and less power consumption.
5) Easier recovery management.

3) Storage Virtualization:

So, consolidating servers as well as the desktops is all great but what happens to the storage requirements then?  Won’t the storage requirements also grow by leaps and bounds?  This is the next question that you are going to get from your clients – internal or external.   This also means that since everything is in one place, one also needs to have a proper plan for disaster recovery and business continuity.   So what does storage virtualization mean then?  It means we would then need to make multiple storage devices appear as a common shared media.  A proper back-up and restore strategy needs to be formed as well then and a proper DRP needs to be done – both local and site failures need to be accounted for.  We will present a more detailed DRP analysis in one of our whitepapers that we are working on.

Major Players:

So, who are the major players in this market?  If you have been following the virtualization world, you already know that VMWare, Citrix and Microsoft are the three leading players in this market right now.  There are other players as well who have entered the market – Red Hat, HP, IBM, Oracle and Virtual Iron Software are some of the other names.  For end consumers like us, the more the competition in the virtualization industry, the more affordable it is going to be for us.  Microsoft’s solution (Hyper-V) is free but that solution is not as robust as the VMWare offering.  A lot has been already said about comparing the two.  Here are some resources to help you with that comparison:

a) VMWare’s Presentation: Here.
b) WindowsIT Pro comparison (this requires a subscription to read the article): Here.
c) Good Discussion @ Virtualization.info: Here.
d) ITComparison.com’s Analysis: Here.
e) Michael Otey’s article: Here.

Do note that we do not recommend using virtualization for your database servers IF you have a highly transactional system or a datawarehousing/data mining system that requires heavy IO activity.  Read more over here.  If you have applications which do not tax the database that much and the IO is relatively less, virtualization works perfectly fine.  This is based on our research as well as limited tests that we have done in our lab & client sites.

Posted in Hyper-V, Technology, Virtual Server, VMWare | 10 Comments »

Converting Physical Servers to Virtual Machines

Posted by decipherinfosys on July 24, 2008

In almost any virtualization project, you will run into the need of converting physical machines to virtual machines. Both VMWare and Microsoft provide solutions for that. Here is the link that gives the details of the vmware converter. And here is the link for the Microsoft Virtual Server Migration Toolkit and another one that details VMM (Virtual Machine Manager) over here.

We have used the vmware one quite a few times and it is pretty easy to use and very robust as well. It does not require any downtime either. Haven’t had any experience with the MSFT toolkit so will post on it once we play with it in our labs.

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Virtualization Wars

Posted by decipherinfosys on July 11, 2008

We have covered virtualization before at our blog but mostly VMWare and a couple of posts on Virtual Server as well. With Windows Server 2008’s Hyper-V, it looks like it will challenge the market even more for ESX Server 3.5. With hardware changes coming in way faster than the software changes, the servers age out faster due to hardware issues rather than the OS. With virtualization, a physical server can easily be migrated into a virtual environment with the same applications and then moved on to a new physical hardware. We have clients who are using virtualization now even in their production environments let alone the development and QA environments.

If you are not already using virtualization in your environments, now would be the time to start getting serious about it. With Hyper-V, the technology moves the virtualization layer directly against the hardware. Hyper-V allows virtualization of both 32 bit as well as 64 bit architectures. MSFT has extended their virtualization platform offering by providing Microsoft App. virtualization (this was known as SoftGrid before) and desktop virtualization. not only that, one can use the System Center Virtual Machine Manager to do centralized management of a virtual set up.

Not only are these choices cost effective by providing us with consolidation and DR/HA (Disaster Recovery and High Availability) choices, it also eases up maintenance work for System Engineers as well as DBAs. An added benefit of consolidation is reduced electricity costs 🙂

Both ESX Server 3.5 and Hyper-V are based on hypervisor based architectures which are better than the previous hosted virtualization technologies. In the case of the hosted virtualization products, one had to run the virtualization software on top of the OS of the machine and that adds a lot of overhead and not only that, it has a longer code execution path for the VMs. Hypervisor based architectures run the hypervisor directly on the hardware which means that there is no OS between the hypervisor and the system hardware. Even though both ESX Server 3.5 and Hyper-V as both based on hypervisor base architectures, there are a good bit of differences between them. We are currently doing some benchmarks with ESX Server 3.5 as well as Hyper-V and will post the results of the tests at our blog as and when they become available and we consolidate them. Till then, you can read more on these over here:

ESX Server 3.5

Hyper-V and the FAQs

Posted in Hyper-V, Virtual Server, VMWare, Windows | 1 Comment »

Some more Virtual Server Resources

Posted by decipherinfosys on November 22, 2007

Here are some good virtual server resources from MSFT:

Virtual Server Operations Guide:

http://technet2.microsoft.com/windowsserver/en/library/ce2499f6-f592-4eec-946f-56ff352e3e291033.mspx?mfr=true

Virtual Server Technical Reference:

http://technet2.microsoft.com/windowsserver/en/library/c3663e92-0992-4f6f-9870-513040f5f2be1033.mspx?mfr=true

Virtual Server Community:

http://www.microsoft.com/windowsserversystem/virtualserver/community.aspx

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Virtualization in the database world

Posted by decipherinfosys on October 26, 2007

Virtualization is rapidly changing how we consolidate our servers for testing and deployment, for training and for disaster recovery. We have VMWare machines running in our office with clustered SQL Server and clustered Oracle environments. It is a great way to test out new software and play around with the new functionality as well as test out your disaster recovery scenarios without investing millions on hardware. It is also a good way to consolidate your servers and use them for development and QA purposes.

Both VMWare’s VMWare Server and MSFT’s Virtual Server 2005 R2 support 64-bit architecture on the host which means more memory utilization on the host seerver (up-to 1 Tera-byte) which translates into the capability of running many more active VMs. When you are getting ready to consolidate your servers into the VMs, you should remember to allocate 32MB per VM to account for the VM overhead. So, if you have an Oracle database for which you have allocated say 2GB of memory (overall), when you move to the VM, you would need (2 * 1024) + 32 MB for the VM. And you need to ensure that there is enough RAM left for the host as well. Another thing to consider is the usage of a SAN for the host server. You should create the VM’s virtual hard drive on a drive that is different than the host’s operating system – this is to reduce any possibility of a drive and spindle contention. Best thing is to use a SAN to help improve the I/O for the VMs. One more things to remember is that the virtual hard drives can be configured with their default settings to dynamically expand as needed. However, this is not good for performance. We would recommend to pre-allocate a fixed amount in order to avoid the performance hit of the expansion.

Here is the link to the whitepapers from VMWare on this topic:

http://www.vmware.com/solutions/whitepapers.html

Posted in Virtual Server, VMWare | 1 Comment »

Using vhdmount to access the virtual disk files

Posted by decipherinfosys on September 23, 2007

In the release of Virtual Server 2005 R1 SP1, Microsoft included a tool called VHDMount which allows one to connect to a vhd disk on your host operating system as if it were a separate physical disk. It makes sharing of the files a lot more simpler. Our partner company, Cerkitek has a good blog post on the usage of this tool. You can access that post here:

http://cerkitek.wordpress.com/2007/08/12/accessing-virtual-disk-files-with-vhdmount/

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