[Gluster-users] about HA infrastructure for hypervisors

[Nathan Stratton]

On Thu, 28 Jun 2012, Brian Candler wrote:

> As I said: don't use 10GE over CAT6/RJ45 (10Gbase-T). That does indeed have
> poor latency.  As I understand it: in order to get such high data rates over
> copper, it has to employ mechanisms similar to DSL lines, like interleaving,
> which means 10G has comparable or even higher latency than 1G.  Switches
> with all 10Gbase-T ports are expensive, only available from a couple of
> vendors, and consume a lot of power.

One more thing on the "don't use 10GE over CAT6/RJ45" debate. Where do you 
get that 10GBase-T has power latency? If you look at 1000Base-T latency 
ranges from 1us to over 12us with 10GBase-T ranging from just over 2us to 
4us a MUCH tighter latency range. When you look ate large packets this is 
even more pronounced. So yes for very small packets 1000Base-T is faster, 
but we are talking about 1 - 2 us difference and only on small packets.

As far as power, original PHYs were almost 7 Watts per port! Today, almost 
every switch out there is less then 1 Watt per port and falling based on 
Moore's Law.

><>
Nathan Stratton
nathan at robotics.net
http://www.robotics.net