Lee H. Marzke on 6 Nov 2017 11:32:19 -0800

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Re: [PLUG] small business server virtualization?

So, obviously it depends.

In the old days the Enterprise would always put each service on it's own hardware. It's just easier
to upgrade/maintain as you mentioned.

Today it's standard to put every service in a VM because it's so easy.   There is still some concern
about one VM hogging resources away from the others - but VMware has resource pools to handle that.
Essentially a resource pool is a  folder with guaranteed amount of RAM/CPU for anything inside.  Think
of RP's as software 'hosts' to prevent any VM interference between RP's   RP's require Essentials Plus

Overhead ?   There is little CPU/RAM overhead of virtulization with VMware, maybe 5%

But the benefit of being able to snapshot / revert / clone , and replicate VM's is worth much more.

If you want something that works out of the box you buy VMware, you can be up and running in
a day.  Don't forget that VMware also provides loads of performance statistics and warning info
which is easier to interpret that command-line KVM'

VMware provides High Availability services.  Why would you need that ?

Because when a Hypervisor fails,  ALL VM's fail - and having all VM's fail at once is much
more severe than losing one physical box.   If you don't have HA,  then concentrating many VM's on fewer
hosts reduced your uptime because so many VM's are affected at once.  HA will restart any
VM's on that failed host within 20 seconds on a surviving host.   Generally nobody even
notices that a host failed because HA recovers it for you.    Lookup ESX: purple screen of death (PSOD)

You should have larger special purpose hosts to run many VM's at once,  Don't make the mistake
of ordering hosts without knowing the requirements.  For instance VMware recommends at least
6 to 8 1GB Nic's per host.

vSphere Essentials give you a license for 3 hosts of 2CPU each, with vCenter included, and not
much else.  You can snapshot VM's and use templates. If you don't have any requirements for maintaining
uptime SLA's  this may be enough.  As you mentioned Essentials costs $500 purchase and about $100/yr maintenance.
Really only recommended for tiny shops with 5 people or less.

vSphere Essentials plus, give you the above, along with
-  HA  If a host fails ( purple screen of death ), all running VM's restart on a remaining host.
-  vMotion ( live migration of VM's between hosts ) allows you to do maintenance on a host without VM downtime.
-  Endpoint introspection - Allow use of agent-less antivirus solutions ( the AV scanning is done in a separate VM, not in Windows) 
        This provides more performance to Windows VM's since they no longer do AV work.
- vSphere replication - replication of VM's live to another local or remote VM.

This runs $5000 purchase for 3 hosts,  and is typically the absolute minimum I recommend for any small business.

With 2 hosts the resources on one is dedicated to HA, so you lose 50% capacity for HA.  With 3 hosts, you lose one host to HA, or
only lose 33% capacity. So it is advantageous to have more but smaller hosts in the cluster.

Note that for HA, vMotion or anything providing high uptime, the VM's generally must be on shared storage such as ( SAN / NAS ) or
alternatively the new vSAN offering from VMware.   vSAN turns internal host disks into a SAN.  ( I also currently run
FreeNAS as storage for my lab, but that isn't as reliable as vSAN )

I've worked with implementations ranging from 2 hosts/Essentials, to 3 hosts Essentials Plus, to 24 hosts Enterprise Plus
so just ask offline if you want more info.  I have a full lab and can demo anything.

The PLUG virtulization panel discussion is archived here: ( discusses KVM and 


----- Original Message -----
> From: "Greg Helledy" <gregsonh@gra-inc.com>
> To: "Philadelphia Linux User's Group Discussion List" <plug@lists.phillylinux.org>
> Sent: Monday, November 6, 2017 1:08:24 PM
> Subject: [PLUG] small business server virtualization?

> Does the overhead of virtualization make sense for small organizations?
> We have various applications running on two physical servers and run
> into the situation where two or more applications need Apache so
> configuration of one potentially interferes with configuration of
> another.  And likewise, upgrades or maintenance of one application
> require the server to be taken offline for a while, cutting off access
> to others.
> Can it make sense to virtualize so that each application has its own OS
> instance, which can be powered on and off, upgraded, etc. independently,
> for a small business?
> It looks like VMWare's vSphere Essentials would run us $500 or so a
> year, is it worth it to pay that?  What's the best alternative as a
> bare-metal hypervisor, Xen?  KVM is a no-go because we have to be able
> to do Windows servers, too.
> --
> Greg Helledy
> GRA, Incorporated
> P:  +1 215-884-7500
> F:  +1 215-884-1385
> www.gra.aero
> ___________________________________________________________________________
> Philadelphia Linux Users Group         --        http://www.phillylinux.org
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"Between subtle shading and the absence of light lies the nuance of iqlusion..." - Kryptos 

Lee Marzke, lee@marzke.net http://marzke.net/lee/ 
Philadelphia Linux Users Group         --        http://www.phillylinux.org
Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce
General Discussion  --   http://lists.phillylinux.org/mailman/listinfo/plug