[ale] Virtualization

[Jeff Hubbs]

My experience - by which I mean VMware ESX in two workplaces and Xen on 
my own - is that virtualization is a case of making deals with the Devil. 

Hardcore this-is-what-I-run-production-on ESX use calls for exquisite 
levels of care, feeding, money, and intelligent thought.  If your IT 
organization doesn't have enough of any of these elements to expend on 
your ESX plant, epic FAIL awaits.  Everything at every level must work 
well and perfectly, for they will be stressed and anything that's not up 
to the task will have everything on and above it crashing down. 

VMware did a reasonable thing by making ESX something that you install 
on bare metal, but in exchange you lose interoperability and 
flexibility.  I liked dealing with Xen (at least as it existed in 
mid-'07) because it insinuated itself at a fairly low level - your host 
instance can be truly yours - and I am drawn to the idea of using 
virtualization for R&D purposes, i.e., that's where server instances 
"gestate" before going to real hardware for testing and then production. 

I am also seeing virtualization as a legitimate way of addressing 
spiraling electrical power consumption.   It makes me feel as though 
using virtualization to *some* degree could be reasonably considered to 
be a requirement for responsible computing. 

Disk subsystems seem to be an Achilles' heel of VM rigs...the next time 
I try anything like this, I want to try basing it on ATA-over-Ethernet.  
The high-dollar canned (rhymes with "crap") iSCSI subsystem in use at a 
former workplace of mine was way too accident-prone to depend on. 

- Jeff





Jim Kinney wrote:
> On Tue, Feb 24, 2009 at 9:50 PM, Christopher Fowler
> <cfowler at outpostsentinel.com> wrote:
>
>   
>> This is my experience as well.  I think many companies look at
>> virtualization as a way to save
>> money on hardware.
>>     
>
> Virtualization seems like a cool toy. But when I see a business use
> many virtualized machines for daily processes, mission critical
> services, etc, it just screams "single point of failure with massive
> consequences".
>
> It also speaks volumes about the overall architecture and design of
> the processes in use that they require multiple machines for load that
> then get virtualized to save money on hardware.
>
> ?!?!?!?!?
>
> Huh?!? WHA?!?!?
>
> Picture this scenario: Product FOO is composed of database, app logic,
> and UI frontend. The designers all insist that their portion requires
> an independent machine to avoid resource conflicts. So 3 VMs get built
> thus placing all the parts on the same machine with even higher
> overhead than if they were on a single, physical machine. Management
> viewpoint is they don't have a new chunk of hardware to buy for this
> process. While true, they did have to buy a HONKIN' box(s) for the vm
> server.
>
> It always seemed to me that virtualization is a good thing for test
> environments and extremely light loads that are not mission critical.
> But the ideal use in a mission critical environment is as a backup
> environment for the real hardware.
>