[GTALUG] Thinkpad T420 as a VM host

[Lennart Sorensen]

On Sun, Jul 19, 2015 at 06:01:46PM -0400, Alex Volkov wrote:
> So I replaced a 4GB memory stick in my Thinkpad  T420 with an 8GB one
> bringing the total amount of available ram to 12GB with maximum of
> 16GB.Even though Lenovo say that the laptop supports only 8 GB of ram total.

You might have just made your machine slower by doing that.  Maybe.
Most modern CPUs are at least dual channel memory controller based,
but can only use the dual channel mode to interleave accesses if the
memory matches in size.  So 2x4GB is fast, and 2x8GB is fast, but 4+8GB
would be slow.  Maybe that is not the case on this machine, and it might
even be smart enough to decide to run in inteleaved mode for the first
4GB on each stick and then get slow for the last 4GB on the 8GB stick,
but I have no idea if it is that smart or not.

And yes it is not unusual for a machine to support more memory than
documented simply because it was never tested to see if it would work,
and hence the documentation simply says it doesn't.

> As it stands now this 4 year old machine becomes a pretty cost-effective
> platform for virtualization:
> 
> * Intel Core i5-2410M
> * 16GB max memory (~$65 per 8GB stick).
> * 2 SATA ports (built-in and ultrabay)
> * 2 mSata ports (one could be used for solid state storage)
> * 1 eSata port.
> * 1 Gigabit ethernet
> * 1 SD card

I suspect it has at least an expresscard slot too somewhere.  Probably a
34mm (You rarely see the wider 54mm ones anymore).

> Canada computers sells refurbished ones for about $300 and I think there
> are some available in Brampton. Also I saw a few similar refurbished
> machines on Amazon.

-- 
Len Sorensen