Dr. Dweeb wrote:
> Keith Parris wrote:
>> Richard Maher wrote:
>>> 1) I saw 10 Gigabit NIC sup****t scheduled for VMS 8.3 (Depending on
>>> which slide you look at it says "Integrity Servers Only"). Now 10x
>>> what a lot of people are using for a cluster-interconnect at the
>>> moment sounds pretty s__t-hot to me! Especially if you're moving big
>>> lock-trees around the cluster. Given that this functionality is less
>>> than a year away, surely some performance figures or at least
>>> anecdotal evidence should be available?
>>
>> One way to estimate the impact is to see how Gigabit Ethernet
>> compared with Fast Ethernet. Bandwidth went up by close to 10x;
>> latency went from about 240 microseconds for a round-trip lock
>> conversion request with Fast Ethernet to about 200 microseconds on
>> Gigabit Ethernet, as measured on a typical Alpha box of the recent
>> past (Wildfire or ES40). So don't expect a 10x latency improvement.
>>
>>> I mean, if I was an Rdb engineer that had used p___-poor DLM
>>> performance as the rationale for sticking all of my R&D eggs in the
>>> stand-alone single-node basket, then I'd be interested in what's
>>> happening with this. Right? "But it's not the bandwidth, it's the
>>> latency that gets ya." Well that brings me to the next slide. . .
>>
>> Rdb sup****ts Row Cache in Galaxy Shared Memory between multiple
>> nodes.
>>> 2) Next Generation Low-Latency Interconnects Post 8.3 (Integrity
>>> Servers Only)
>>>
>>> Am I the only person getting their jollies out of this or what?
>>
>> Nope. I also find this exciting.
>>
>> Potential candidate technologies one would naturally want to look at
>> could include Infiniband and RDMA/iWARP.
>>
>> Infiniband promises low latency, but hasn't really taken off much in
>> the industry yet, and hardware is expensive. Some initial proponents
>> have subsequently backed out (like Intel). A lot of people are
>> waiting to see how this turns out.
>>
>> RDMA/iWARP looks to have broad potential industry sup****t, and will
>> quite possibly be built into commodity Ethernet adapters. Latency
>> wouldn't be quite as low, but price would be low and
>> price/performance very good.
>>
>> Should be interesting. In any case, I'm know VMS Engineering has its
>> finger on the pulse of the technologies available in the marketplace,
>> and will provide a quality solution with the best interests of the
>> customers in mind.
>>
>>> Will there be a special limit on the distances between nodes for
>>> this stuff to work? (Like memory channel) Can you have a Disaster
>>> Tolerant Low Latency Cluster?
>>
>> Infiniband has some fairly low distance limitations, unless you
>> include an Infiniband router, and that's for IP traffic.
>>
>> For anything Ethernet-based I don't expect distance limitations.
>> Other than how far you can drive light over fiber, there's no
>> inherent distance limit in Gigabit Ethernet today, for example. But
>> of course the longer your inter-site distance, the more delay there
>> is due to the speed of light over the distance, which mitigates
>> against low latency. ---
>
> Indeed - it is the physical absolute barrier for comminucation of
> data or energy over distance, something to do with instantaneous
> causal events not being possible and all that (if I recall my physics
> of relativity correctly) :-)
>
> Dweeb.
>
But perhaps not
http://homepage.sunrise.ch/homepage/schatzer/space-time.html
Dweeb.
>> Looks likely I'll be doing a hands-on workshop at HP Technology Forum
>> on Long-Distance OpenVMS Clusters. We'll explore some of the impacts
>> of long distances on performance in that workshop, for folks who are
>> interested.
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