Hi Stephen
The recommended minimum connection is 1Gb. This is to handle peak rates.
However we have not seen the experiments saturate T2 links. Much depends
on your local setup - how much KSI2K the site provides and the number of
disk servers available.
You may get away with a smaller connection than that recommended but
ATLAS users will need to say if this is restricting their use of the
site.
Jeremy
-----Original Message-----
From: Testbed Support for GridPP member institutes
[mailto:[log in to unmask]] On Behalf Of Stephen Childs
Sent: 18 June 2008 12:00
To: [log in to unmask]
Subject: Bandwidth to sites (esp. Atlas)
As a result of involvement with LCG (mainly Atlas) for the first time in
earnest this past few weeks, we find ourselves having conversations with
our upstream networking people about the volume of traffic being
transferred.
We are being asked what bandwidth we require. We are currently on a
100MBit link, but as traffic to us goes over the departmental network,
even this was seen as too high a rate for sustained use. We are
therefore
rate limiting our SE to around 8MiB/s (~ 64MBit/s). Transfers from Atlas
seem to be succeeding now -- at lower rates we noticed some timeouts
during the throughput challenge.
In the medium-term we will get all our networking sorted out so there is
a
dedicated high-speed path to our grid machines, but in the meantime it
would be useful for us to have a figure for typical connection speeds
for
LCG sites.
What is typical bandwidth available into GridPP T2s? Is this documented
anywhere? I have been trying to use gridview to see what the transfer
rates into UK sites were (say from RAL), but can't seem to get sensible
graphs.
Stephen
--
Dr. Stephen Childs,
Research Fellow, EGEE Project, phone:
+353-1-8961797
Computer Architecture Group, email: Stephen.Childs @
cs.tcd.ie
Trinity College Dublin, Ireland web:
http://www.cs.tcd.ie/Stephen.Childs
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