perfsonar development work

[Nicolas Simar <>]

Info from Vedrin about the LS and the MA availability below.

-------- Original Message --------
Subject: Re: [Fwd: Re: [pS-dev] Operational support for Discovery]
Date: Tue, 25 Jul 2006 01:33:16 +0300
From: Vedrin Jeliazkov 
<>
Reply-To: Vedrin Jeliazkov 
<>
To: Nicolas Simar <>,        "Maciej Glowiak" 
<>,        "Roman Lapacz" <>, 
   "Szymon Trocha" <>,        "Andreas 
Hanemann" <>,        "Loukik Kudarimoti" 
<>,        "Vedrin Jeliazkov" <>
References: 
<>

Hi Nicolas, All,

Sorry for my late response - I'm right back from a hike in the Bulgarian
mountains (and planning another one ;-)

Nicolas Simar 
<>
 wrote:

<snip>

> - Vedrin, you mentioned some times ago that you prefer to have each NREN 
> to deploy its own LS and have its services registered at it to test 
> different performances. Is it something we should do?

Well, I suggested each NREN/domain to have its own LS because our experience
here at ISTF shows that having more than ~100 interfaces registered by RRD
MA(s) in LS every 30 seconds puts too much stress on our server (shared
between RRD MA-J, RRD MA-P and LS, 768 MB RAM, 1 GHz CPU). In fact we were
forced to reduce the number of published interfaces to 80 and the 
registration
frequency to once every 120 seconds. A more powerful server (or a 
dedicated LS
server) might be able to handle a bigger load. However, I doubt whether a
single LS would be able to handle several thousands of items efficiently 
right
now. That's why a more scalable approach (at least for the time being) would
be to spread the load between a higher number of LS (ideally, hosted by 
every
NREN/domain). Of course, some NRENs/domains might prefer to register a small
number of items in the LS of another NREN/domain, willing/able to host this
info without any impact on performance.

I'm also wondering if it would be a good idea to configure all these 
NREN LSs
to register in some "top level" LS, whose sole purpose would be to
host/provide information for the location of other LSs (without details for
interfaces or other data items). This might be an efficient and scalable 
setup
for the time being, while the work on Multi-LS goes forward. It would 
provide
a single point of entry for visualization clients, instead of the otherwise
unavoidable full list of the addresses of all available LSs, which has to be
updated manually quite frequently. If we decide to deploy such "top 
level" LS,
the best place for it would be in a location with highly redundant network
connections and power supplies, as well as responsive operational support.
Some hints could be provided by our SmokePing statistics of RRD MA services
availability:

NREN                 RRD MA AVAILABILITY (last 90 days)

Abilene              88.21%
ISTF/ACAD (Java)     99.19%
CARNet               93.54%
Cesnet               65.54%
ESnet                98.59%
GEANT                99.93%
GRNET                83.84%
MREN                 60.81%
PIONIER (RRD)        69.98%
RNP                  99.60%
SEEREN               99.96%
SWITCH               90.26%
Uninett              99.53%

SEEREN has the highest availability, closely followed by GEANT, RNP, Uninett
and ISTF in decreasing order of preference. When taking into account network
latency from different points in the world, as well as "politics", I would
certainly vote for GEANT to host the "top level" LS in which all other LS
would have to register.

The American guys are below the 99% threshold and this cannot be 
justified by
failing intercontinental network connections, as demonstrated by:

http://netmon.acad.bg/smokeping?target=ip4.k-w.DRS-D-US

which shows 99.93% reachability of d.root-servers.net, located in the
University of Maryland, College Park MD, USA, for the same period of time
(last 90 days).

Kind regards,
Vedrin



--
Nicolas
______________________________________________________________________

Nicolas Simar
Network Engineer

DANTE - www.dante.net

Tel - BE: +32 (0) 4 366 93 49
Tel - UK: +44 (0)1223 371 300
Mobile: +44 (0) 7740 176 883

City House, 126-130 Hills Road
Cambridge CB2 1PQ
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