I am forwarding this message from Neil Smith, the HENSA cache
administrator (who is not a member of the lis-elib list).
Please make sure that you include Neil ([log in to unmask]) in the
To: if you want him to receive any replies, comments, etc.
Brian
------- Forwarded Message Follows -------
To: Brian Kelly <[log in to unmask]>
Cc: [log in to unmask], [log in to unmask], [log in to unmask]
Subject: Re: National Caching Issues (was Re: eLib standards guidlines (fwd))
Date: Wed, 06 Mar 1996 17:15:14 +0000
From: "N.G.Smith" <[log in to unmask]>
>Why are we apparently worse off than Europe? Is it because
>we make greater use of networked services?
Not necessarily.
NORDUnet has a 34Mb/s link to the United States, (ironically this
passes through London). I don't know what size the population using
that link is, but I imagine that the link is (relatively) idle for a
large proportion of the time.
HENSA, along with other caches that don't use HENSA as a parent, has to
share the 4Mb/s link that the rest of the UK academic community uses.
With congestion leading to the majority of packets never making their
way to the US in the first place it is not surprising that these
services are struggling.
Hopefully the situation will improve when the new 8Mb/s link finally
comes on-line. At this point UKERNA have indicated their desire to
route HENSA's cache traffic via the old link, thereby ensuring that the
cache is the fastest route to the US.
<gripe>
Incidentally, while the HENSA caches are currently handling in excess
of one and a quarter million accesses each day, this figure could be
much higher, and the cache hit-rate much better if some of the larger
bandwidth users actually made use of the cache.
Here's the top users of the cache. If you think that your institution
ought to be here but isn't, you need to do some arm-twisting:
leeds.ac.uk 99517
cf.ac.uk 75233
brunel.ac.uk 59176
soton.ac.uk 49610
york.ac.uk 39259
hull.ac.uk 35267
ed.ac.uk 34810
bath.ac.uk 33175
qub.ac.uk 31369
city.ac.uk 30500
uwe.ac.uk 29254
warwick.ac.uk 29118
dur.ac.uk 28979
bcc.ac.uk 27136
keele.ac.uk 24348
king.ac.uk 23818
livjm.ac.uk 22751
plym.ac.uk 20602
ex.ac.uk 17193
Notable omissions: ic, ral, ucl, cam
</gripe>
>I understand that HENSA have received funding which will enable them
>to address the overload problems (Leeds and HENSA will both support
>a national cache, which will help overcome the single point of
>failure problem). I'm not sure if you're arguing against the use of
>national caches, or pointing out a problem which may have been
>fixed / may about to be fixed.
>
>Brian
HENSA now has six machines all serving the caching requirements. As I
said these handle about 1.25 million requests a day. I estimate that
they could easily handle five times this load.
The more people using the cache, the more efficient the use of the bandwidth
and the better the performance for everyone.
Spread the word.
Neil Smith
HENSA Unix
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|