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What are the practical (or real) advantages of Intel VT and TxTtechnology (Q8200 vs Q9300) ?



 
 
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  #21  
Old August 7th 09, 10:13 PM posted to comp.sys.intel
Yousuf Khan
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Posts: 914
Default What are the practical (or real) advantages of Intel VT and TxTtechnology (Q8200 vs Q9300) ?

Robert Myers wrote:
I had a really hard time visualizing a VM until I actually used one.
Now things are much more clear, and, while I still don't understand
the virtue of running 100 Linux servers on a mainframe, I can see some
definite advantages for me:

I can run Linux as a guest on Windows and have access to both
environments at the same time.

I'm assuming that it's the VT-x technology that allows me to run the
virtual Linux box with it's own IP address. My router sees two
distinct computers, in spite of the fact that I have but one ethernet
card. I can ssh into the guest Linux box from the host box and use
sftp to move files back and forth between the two machines.


The virtualized network interfaces actually predates the virtualized
processor environments by many years, and it's not really achieved
through the virtual processor mechanisms, nor is processor
virtualization necessary. It's simply a matter of changing the MAC ID of
the packets. Usually the MAC ID is whatever is built into the firmware
of the network adapter, or sometimes even into the BIOS firmware of the
host machine. But this identifier is interceptable and changeable.

Prior to processor virtualization, I used to run Sun machines with
multiple websites, each website was assigned its own virtual network
interface and was thus easily routable by MAC ID alone.

Yousuf Khan
  #22  
Old August 8th 09, 01:28 AM posted to comp.sys.intel
Robert Myers
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Posts: 606
Default What are the practical (or real) advantages of Intel VT and TxTtechnology (Q8200 vs Q9300) ?

On Aug 7, 5:13*pm, Yousuf Khan wrote:


The virtualized network interfaces actually predates the virtualized
processor environments by many years, and it's not really achieved
through the virtual processor mechanisms, nor is processor
virtualization necessary. It's simply a matter of changing the MAC ID of
the packets. Usually the MAC ID is whatever is built into the firmware
of the network adapter, or sometimes even into the BIOS firmware of the
host machine. But this identifier is interceptable and changeable.

Prior to processor virtualization, I used to run Sun machines with
multiple websites, each website was assigned its own virtual network
interface and was thus easily routable by MAC ID alone.

I mentioned it mostly because the machine can talk to itself without
the intervention of a third party. For me, it's very convenient
because I don't have to worry so much about which environment
something is in.

Mostly, I was always aware of the privileged instruction issue and, no
matter whether it could be gotten around or not without VT-x, it
always sounded like it had to be baling wire and chewing gum, and I
had no interest in experimenting. That is to say, whether it's
supposed to work or not, I wouldn't bother with virtualization without
explicit hardware support for it because of the issues with
virtualization and x86. Good for vmware that they could work around
it; it wasn't worth any kind of risk for me. Now that it's well-
supported and can be had for free, it's pretty nifty.

Robert.

  #23  
Old August 8th 09, 02:53 PM posted to comp.sys.intel
[email protected]
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Posts: 14
Default What are the practical (or real) advantages of Intel VT and TxT

In article
,
(Robert Myers) wrote:

... while I still don't understand the virtue of running 100 Linux
servers on a mainframe


One of the major advantages, from the PoV of IBM, and of the people in
their customers who have built their careers round mainframes, is that
it provides a new reason for having a mainframe.

It can also take up less space and consume less power, and so on, but
that depends on how hard your "Linux machines" are being worked, and
what the other pressures on the organisation are.

As an example, my employers have a whole lot of PCs, running Windows or
Linux, running overnight each night testing the day's changes to
CPU-bound software. We use the developer's desktops for this overnight,
as well as lots of other machines. Notably, when a developer's desktop
finishes its three-year depreciation life, it goes into the test farm,
and does another 2-4 years there, depending on how fast it goes obsolete
or breaks down.

Some corporate IT management types have been trying to convince us to
buy blade servers for the test farm. They claim it will save money, but
we can't see how and they can't demonstrate it. We have enough space for
the old machines. While we could cram the same CPU power into less space
with blade servers, we have no other use for the space unless we are
allowed to hire some more people. Blade servers, like mainframes, are a
more expensive way of getting the same CPU power than ordinary desktops
bought on a bulk purchase deal.

--
John Dallman

"C++ - the FORTRAN of the early 21st century."
  #24  
Old August 9th 09, 11:07 PM posted to comp.sys.intel
Robert Myers
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Posts: 606
Default What are the practical (or real) advantages of Intel VT and TxT

On Aug 8, 9:53*am, wrote:
In article
,

(Robert Myers) wrote:
... while I still don't understand the virtue of running 100 Linux
servers on a mainframe


One of the major advantages, from the PoV of IBM, and of the people in
their customers who have built their careers round mainframes, is that
it provides a new reason for having a mainframe.

It can also take up less space and consume less power, and so on, but
that depends on how hard your "Linux machines" are being worked, and
what the other pressures on the organisation are.

It seems as if, by virtualizing Linux, you are giving up one of the
few genuine advantages of mainframes: they are usually not an
attractive target for hacking. If you virtualize Linux on them, the
only advantage you have left is that it's not x86, which advantage you
can get from other platforms (even and perhaps most compellingly
Itanium) at a much lower price.

Mainframes like to stay busy (translation: if your mainframes aren't
busy, you're burning big money), and aggregating lots of servers is
one plausible way of keeping any computer running servers, which spend
much of their time waiting, busy. I assume that the sales folks at
IBM have the pricing worked out (the same hardware is much cheaper if
it runs Linux) so they can make the case with a straight face, but
Itanium running HP-UX still sounds pretty attractive by comparison.
Not my side of the universe, anyway.

For people running lots of servers, the need for virtualization is
obvious and hardware support on x86 is a no-brainer if you're not
trying to protect Itanium, as Intel no longer is. For the rest of us,
it looks like a neat way to build sandboxes very cleanly.

As an example, my employers have a whole lot of PCs, running Windows or
Linux, running overnight each night testing the day's changes to
CPU-bound software. We use the developer's desktops for this overnight,
as well as lots of other machines. Notably, when a developer's desktop
finishes its three-year depreciation life, it goes into the test farm,
and does another 2-4 years there, depending on how fast it goes obsolete
or breaks down.

Some corporate IT management types have been trying to convince us to
buy blade servers for the test farm. They claim it will save money, but
we can't see how and they can't demonstrate it. We have enough space for
the old machines. While we could cram the same CPU power into less space
with blade servers, *we have no other use for the space unless we are
allowed to hire some more people. Blade servers, like mainframes, are a
more expensive way of getting the same CPU power than ordinary desktops
bought on a bulk purchase deal.

Nothing about blade servers makes sense to me except that they are
cute and are more readily adapted for telcos.

I have yet to see the TCO argument about older PC's settled
definitively. Most calculations I've seen indicated, a few years ago
at least, that computers aged out of being cost effective for compute-
intensive operations after about three years. After that, you were
better off buying new than continuing to pay for electricity to run
obsolete equipment. Where the break-point is depends on the cost of
electricity, obviously. It also depends on the time derivatives of
watts/flop, of new-hardware-$/flop and of the cost of electricity.
From the POV of a departmental budget, though, maybe you don't care
about the cost of electricity.

Robert.
 




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