>> How exactly does that work? I know how I *thought* it worked, but 
>> apparently I'm wrong; I heard one of our head IT guys complaining that 
>> we actually have more Server 2003 Enterprise installations running 
>> than we're "supposed to".
> 
> Licencing's not my specialty. Sounds like you have a certain number of 
> licences and you have more servers than that.
> A previous company I worked for had a site-wide licence for certain 
> apps. Meant they could install as many as they liked and still paid a 
> fixed amount every year (support/upgrade contract). It's expensive for 
> smaller companies, but as the number of PCs increase, it becomes more 
> reasonable than paying for each one.

Right. Well we definitely have a company-wide license for Windows XP, 
Office 2003, and a few other bits. I *thought* we had a company-wide 
license for all the products we've licenced, but perhaps not?

> I don't know if it's still an option. As I said, I don't do licencing if 
> I can help it.

Amen! But some of us don't have that luxury. :-S

>> "Supported" and "working" aren't the same thing. ;-)
> 
> Indeed. The problem with multiple SQL instances in VMs is IO. You can 
> allocate CPUs and memory to specific VMs, but there's still a single IO 
> channel, and SQL database tend to be IO bound more often than CPU or 
> memory.

Yeah, database engines by definition are I/O hungry (and memory hungry 
if you want to cache some of that rather than reread it a zillion 
times). Depending on what you're doing it can be CPU-heavy too, but 
mainly just I/O.

I'm sure it'll *work*, but how fast...? ;-)

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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Invisible wrote:
> 
> But surely if you're going to run a guest OS on the physical host CPU, 
> the host CPU would need to have hardware support for enforcing the host 
> seperation?
> 

There's two ways to do it. The other one needs hardware virtualization 
support (practically any C2D+ and X2+ -processors do have it nowadays) 
and the other one uses somekind of simulation (dunno for sure how - but 
ie. Xen and Linux with slightly modified kernel can do this without 
mentionable powerloss).

-- 
Eero "Aero" Ahonen
    http://www.zbxt.net
       aer### [at] removethiszbxtnetinvalid

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Nicolas Alvarez wrote:
> 
> That's apparently a bad idea. The VM would have different hardware than your
> real machine. It's like taking the HD off and booting it on a machine with
> completely different CPU, motherboard, network card, graphics card...
> 
> At least Windows would pop up a dozen "new hardware detected" messages :)
> 

But that's Windows ;). With Linux, you can compile different kernel for 
the VM/emu and ie. create another X.org -config file and use it with the 
VM/emu.

-- 
Eero "Aero" Ahonen
    http://www.zbxt.net
       aer### [at] removethiszbxtnetinvalid

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Invisible wrote:
>> VMWare's ESXi is free now, though that's a server-level product, not 

Isn't ESXi a hypervisor like Xen? Meaning that it kind of runs even 
under the main-OS, not on it.

> 
> Until yesterday, the only products I'd heard of where Bochs (only runs 
> on Linux) and VMware (AFAIK that's extremely expensive). Oh, and doesn't 

VMWare has several tools available free of cost. Check the website ;).

-- 
Eero "Aero" Ahonen
    http://www.zbxt.net
       aer### [at] removethiszbxtnetinvalid

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Invisible wrote:
> Presumably that requires *very* specialised hardware though?

Yes, but nowadays it's built into all the CPUs already. You couldn't do 
something like this on, say, a 68000 or an 8086.

-- 
Darren New / San Diego, CA, USA (PST)

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Invisible wrote:
> I've heard of plenty of VMs that run on Linux, but I wasn't aware that 
> any free ones existed for Windoze.

Go to microsoft.com and do a search. :-)

-- 
Darren New / San Diego, CA, USA (PST)

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Invisible wrote:
> the emulated CPU to be maybe 1,000,000x slower than the real one, 

How many machine instructions do you think it takes to execute an 
interpreter for a machine instruction? A hundred maybe, but a million?

-- 
Darren New / San Diego, CA, USA (PST)

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Gail wrote:
> Yup. But you'd also need 100 licences if you had 100 seperate physical 
> servers, so it kinda works out cheaper to buy a single large server and 
> virtualise several 'servers' onto one where possible.

A good mainframe these days will run 30,000 images without much problem.

-- 
Darren New / San Diego, CA, USA (PST)

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Gail wrote:
> 
> Then, of course, there's Hyper-V built into Server 2008.

Which, according to Hype(tm) is Ultimately New Technology Innovation By 
Microsoft(R), since it uses the Brand-New Never-Before-Seen hypervisor 
technology (which is, still according to the same Hype(tm), pretty much 
similar as in Xen and AFAIK with ESXi, but apparently they don't count, 
since Innovating Sells).

-- 
Eero "Aero" Ahonen
    http://www.zbxt.net
       aer### [at] removethiszbxtnetinvalid

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Gail wrote:
> 
> Indeed. The problem with multiple SQL instances in VMs is IO. You can 
> allocate CPUs and memory to specific VMs, but there's still a single IO 
> channel, and SQL database tend to be IO bound more often than CPU or 
> memory.

With Xen you can allocate whole disks or RAID-arrays or whatever and 
amount X of RAM to be used straightly by the VM. In my experience the 
lag is mostly unnoticeable (yes, it probably will be more noticeable 
with DB-server, which I'm not running on VMs (well, there are MySQL 
installations on at least 2 VM's, but they're really small DBs), but 
depending on DB-size etc the saved cost of another HW can possibly give 
you even better HW for that one machine to have better IOs for the DB, 
it's not purely black and white).

Then again, MS surely don't want to support Xen, while they're working 
on HyperV - no wonder SQL Server ain't supported on such 
competitor-software ;).

-- 
Eero "Aero" Ahonen
    http://www.zbxt.net
       aer### [at] removethiszbxtnetinvalid

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