[CentOS] OT: Why VM?

Fri May 27 22:51:28 UTC 2011
Ljubomir Ljubojevic <office at plnet.rs>

James B. Byrne wrote:
> On Fri, May 27, 2011 14:36, Jack Bailey wrote:
>>   1. Get more out of your existing resources: Pool common
>> infrastructure resources and break the legacy “one application
>> to one server” model with server consolidation.
> I have difficulty with this statement on so many levels that it is
> hard to know where to begin.  Perhaps the most egregious is the
> mindless equating of server with host.  What measurable benefits
> accrue to a firm from 'breaking the legacy', whatever that means.

It looks like you are not familiar whit this model of business. Let say 
a company buys one design system that includes server backend and 
continuous support. Since they are responsible for entire environment, 
and in fear of admins braking anything by upgrading, and fearing that 
additional roles of that server might impair their product performance 
wise, they demand separate server just for that role. This happened 4 
years ago, and was paid some, lets say, $550.000.

7 years ago accountants purchased a software product with their own 
database server. Same conditions, nothing else can be run on it.

Let say that company that sold accounting software went out of business. 
Their product still runs perfectly on ancient "Red Hat Linux 7" server, 
but it is compiled for against gcc and other libraries from that time. 
Any change could brake  that app. And hardware is for one old and it is 
not known if it will last a year or so, HDD's might fail and MB does not 
support modern ones. And RHL 7.x has no drivers for modern hardware.

What to do? Virtualize both systems on strong modern hardware. You will 
get safe hardware for your ancient software and you will even get better 
speed and users will be much happier.

>>   2. Reduce data center costs by reducing your physical
>> infrastructure and improving your server to admin ratio:
>> Fewer servers and related IT hardware means reduced real
>> estate and reduced power and cooling requirements. Better
>> management tools let you improve your server to admin ratio
>> so personnel requirements are reduced as well.
> Personally, my experience is that, if anything, running multiple
> systems on a vm host measurably increases the administrative burden
> per host.  For one thing, you now have multiple instances to update
> and to keep secure whereas before you had one OS to worry about.  If
> we had tens or hundreds or thousands of servers then yes, I can see
> the benefits.  We, however, do not deal with equipment on that
> scale.

Here they are saying about number of *hardware* servers/hosts and people 
needed to service them, to keep them running. If you have 30 servers 
now, you need to update all of them weather they are virtualized or not.

But if you move them to 2 strong VM hosts, you admins will not have to 
worry about 30 PSU's, 30 x X HDD's/RAID volumes, your Power consumation 
will drop lets say 10-20 times, you will not need 30 strong UPS's on few 

You will also avoid several heavy duty network switches, and performance 
wise network traffic would be visualized with enhanced speed.

>>   3. Increase availability of hardware and applications for
>> improved business continuity: Securely backup and migrate
>> entire virtual environments with no interruption in service.
>> Eliminate planned downtime and recover immediately from
>> unplanned issues.
> I suppose that moving VM instances as file systems provides a real
> value by eliminating the setup and configuration required to get
> bare metal to flash up in a usable fashion.  This is in fact the
> only area that I see a real advantage to VM over bare metal
> installs.
>>   4. Gain operational flexibility: Respond to market changes with
>> dynamic resource management, faster server provisioning and
>> improved desktop and application deployment.
> I have no idea how deploying VMs to a company's desktop workstations
> could possibly benefit the firm.,

Here is real world example for a small company with 20-30 workers. This 
was 3-4 years ago, in my Linux server beginnings. All they have known so 
far is Windows XP. I got a job to provide new Access database server 
(don't ask). I wanted to give them cheap RAID capability  so I used 
integrated nVidia SATA RAID 1 with 2 HDD's and since server had to be 
Windows (XP Pro so I do not brake a budget, they accepted RAID without 
real understanding what it is), and they are now stuck the whole time 
with crappy RAID drivers and braking the RAID from time to time. That 
"server" is also used as Windows desktop for owners wife for Access 
accounting, Electronic payment etc...

When CentOS 6 is out, I intend to install it on bare metal, add some 
RAM, set software mdraid RAID 10 and move already set Win system to VM 
(I know how to reset HDD drivers). She will be able to use her familiar 
desktop and apps, and I will be sleeping much better not thinking what 
will happen if servers MB dies and I am stuck with non functioning 
HDD's. The I will teach her to use Linux for net surfing and USB flash 
plugging/copying so we avoid possible viruses.

What is more, if you need to get someone to test some new 
OS/software/combination, what better way to do it then installing VM 
image onto his desktop so he can use his current system for productivity 
and to test new software without braking anything or thinking about 2 
keyboards and mouses, space to place new bare metal system, etc.. You 
can even install same image (install once use many times) on numerous 
desktops and can even install several VM's with competitive products 
without any hassle about braking something. You can have few hundred 
people simultaneously testing several products and at the end of the day 
they can still do their jobs on your original system. And if you can 
update/replace those VM's with new versions as fast as you can copy them 
over the network remotely, without physical presence of and admin, thus 
having lesser people on the support staff.

>>   5. Improve desktop manageability and security: Deploy, manage
>> and monitor secure desktop environments that users can access
>> locally or remotely, with or without a network connection, on
>> almost any standard desktop, laptop or tablet PC.
> Again, how is this accomplished and what are the advantages over a
> single OS install?  None of the above claims have anything to do
> with VM per se as far as I can see.

Breach of access to flash/floppy/DVD-RW comes to mind. Even encrypted 
file system on Linux (VM data is protected inside) while they actually 
then run and use insecure windows guest.