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Virtual Servers are a new way to solve some old problems,
mostly to do with server hardware getting old and failing.
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On the rest of this webpage are some quick facts about Virtual Servers.
Find out more by visiting our:-
Frequently Asked Questions
page
our:-
Virtual Servers - In Depth page
or use the following webform to ask a question:-
If you prefer, you can, instead, email your question or comments to info@virtualiser.co.uk |
Full installations of Windows Server operating systems that are
running on imaginary hardware - but they don't know that.
The imaginary
hardware environment is provided by "Server Virtualisation" software
(also called the Hyperviser layer)
running on another, real, Windows computer (called the host) which could be any
version of Windows Server 2000 or 2003 or even Windows 2000 Professional or Windows XP.
The leading programs in the field are provided by VMWare and
Microsoft
themselves.
These programs will also "virtualise" all workstation
versions of windows going back to Windows 3.1 - remember that one?
Besides break down, almost nothing. A virtual server is not so good for playing
high-end games and graphics applications that benefit from a graphics
co-processor in a real graphics card.
If you're after the last drop of
performance from your CPU then a physical server will perform better.
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They require an extra operating system licence for the host computer. |
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The host computer uses up some of the available resources of the physical machine which are therefore not available to the virtual server. |
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As a rough guide the host should have 512mb of RAM to itself and will use up 10% of the processor power. |
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You may have to buy a copy of the virtual server software. Although many server virtualisation programs are free, the best ones, such as VMWare's ESX server, still require you to buy them - an old-fashioned concept, I know |
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All your eggs in one basket: if the physical server goes down then so will all the virtual servers running on it. |
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Increase the size of its hard drive, add a second hard drive or increase the amount of RAM it has installed just by making configuration changes on the host - as long as the host has the extra memory and disk space available. |
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Multiple virtual servers can run on one host computer. Up to 64 virtual servers can run on one host, but that would be some host! The amount of available RAM on the host usually determines how many virtual servers can be run simultaneously - 512mb minimum per virtual server is a rough guide. |
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The same Virtual Server can run, unchanged, on different host computers which can have almost any combination of hardware. The virtual server doesn't need to know about the underlying real hardware, or Hardware Abstraction Layer (HAL), or have to have any drivers installed for the real hardware. |
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You can quickly and easily take snapshots of a Virtual Server without interrupting its operation. Snapshots are like System Restore points in Windows XP, only more reliable. |
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A complete backup of the
virtual server can be made just by copying a few files (one of
the files is likely to be bigger than 4gb). If you use the Volume Shadow Copy service on a Windows Server 2003 host, this can be done automatically and at scheduled intervals without shutting down the virtual server |
My company is quite happily running Windows NT4 and Microsoft Exchange
5.5 but the hardware it's running on is getting old and unreliable and
the hard drive is close to full capacity.
If I buy a new server it will be hard, if not impossible, to get NT drivers
for its hardware components.
It looks like I'm forced to upgrade to Windows Server 2003 plus Exchange 2007.
Turn your existing server into a Virtual Server.
Buy a brand new reliable, more powerful server running Windows Server 2003 with
whatever hardware you want.
Download VMWare's free VMWare Server product.
Download the VMWare's free conversion software to perform the Physical to
Virtual conversion or get someone, like us, to do it for you.
Run your existing Windows NT plus Exchange 5.5 setup indefinitely as a virtual
server on this new host machine.
The imaginary hardware that the NT server is now running on will never wear out and, with the new server,
the system is likely to perform faster than the original physical server.
The virtual server version of your Windows NT + Exchange 5.5
setup will behave exactly as the old physical version: same IP address,
same name, same Windows Domain membership and security identifiers.
Think of it like Rimmer in the TV series Red Dwarf. Although the real
Rimmer had been dead for millennia, he lived on is some sort of virtual form.
Your company only has a single Windows Active Directory Domain Controller server and you're worried about losing the domain information if it were to fail but your company cannot justify the expense of purchasing and supporting a second Domain Controller.
Windows Active Directory works best with 2 or more Domain
Controllers as username, password, DNS, Group Policy and other important
information is automatically replicated between all Domain Controllers.
If one Domain Controller fails then users can continue to logon to their
PCs and access network file-shares and services that were not located on the failed server.
If the failed server needs to be re-installed from
scratch then it can use one of the other servers to join the Windows
Domain and then be promoted back to a Domain Controller.
Let's say that you recently bought a new Windows Server 2003 server
and still have the installation CD for your previous Windows Server 2000 machine.
Buy VMWare Workstation or and
install it on one of your Windows XP Workstations - one of your newer ones.
Install and configure a Windows 2000 virtual server to run on the
XP workstation.
Join it to your existing domain and promote it to a
Domain Controller - your domain must be running in Windows 2000
compatibility mode for this to work.
The virtual server will have to be started manually each time the XP Workstation
reboots but, as long as it's
turned on once a week and left on long enough for the Active Directory
changes to be replicated from the main server, it will contain a full
copy of your domain information which could save the day when your main server fails.
Your management team use Blackberries for push email and you want to install Blackberry Enterprise Server (BES) on your network to closely interface with your Exchange Server but, as a small company, you only have one server and BES insists on being installed on a server which doesn't have Exchange installed on it.
Use your main server to host a virtual server on which BES
is running.
It works, even if your Blackberry contact says it's unsupported - I've done it.
Your main company server is so important to your operations
that every hour of downtime will cost you £100s or £1000s.
You already have your company data backed up to several different places and take
regular images of the server's system drive.
Your server has redundant RAID arrays, redundant power supplies and redundant this and that but
you still lay awake at night wondering what will happen if it all fails.
Your have the server manufacturer's super gold standard support package,
where they're parked round the corner in a van with its engine running,
but you heard of a case where a replacement server part was in short
supply and it took 10 days for it to be imported from Japan.
Your IT manager has suggested server clustering but that sounds horribly
complicated and expensive.
Convert your main physical server into a virtual one and run
it on the same physical server as before but under VMWare Server.
Install the Virtual Server on a partition separate from the host's
system partition and have all your data on a 3rd partition.
Buy another server from a different leading
manufacturer and install VMWare Server on it as well.
Set up replication
of the main host server's data partition and the one containing the
virtual server to the standby host - alternatively store the data and a
copy of the virtual server on a SAN/NAS
separate from the server itself.
When the primary virtual server fails,
due to a hardware failure on the host, start the copy of the virtual
server on the standby host and things should be back to normal with,
perhaps, 15 minutes of downtime.
Over time you've acquired 6 servers which are all now over 5 years old and need replacing but you don't fancy having to buy 6 new servers and pay for 6 hardware support contracts.
Assuming that you can buy a server with a specification
powerful enough to run all 6 servers then just buy one physical server
and host all 6 virtual servers on it.
This will save on space and the amount of electricity required to run all your servers.
If you think that Solution 1 is a bit "all your eggs in
one basket" then buy 2 physical servers, each with just enough resources
to run all 6 virtual servers, even if a little slowly.
Put 3 virtual
servers on each host machine.
Divide each host's disk array into 3
partitions and use partition 1 as the host's system partition, use
partition 2 to hold all six virtual servers and store all company data
on the 3rd partition.
Although only 3 virtual servers are running on
each host, keep all 6 virtual server files up to date on partition 2 and
keep both data partitions in sync.
If one host fails or needs to be taken
down for maintenance then the other host can temporarily run all 6
virtual servers and all that users will notice is a slight drop in
performance.
The replacement motherboard for your server is going to take at least 2 weeks to be delivered. You've got a current disk image for the server's system drive and all the data is backed up but your business is at a standstill while the server is repaired.
Use the disk image to get your server working as a virtual server
which can run on any form of computer including a Windows XP PC.
When your server
is eventually fixed you can either restore the original image or
continue working as a virtual server running on your repaired server.
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