May 14, 2003
Because much of the recent activity on the IDD system has been due to
the ongoing deployment of version 6 of the LDM, the status reports of
the two have been combined into one.
A stable version of LDM 6.0 was released on April 9, 2003
and is being deployed throughout the IDD system.
Improvements to the LDM since the last Policy Committee meeting include
Bugs have been fixed (including one that caused the
LDM system to crash)
Real-time statistics and IDD topology information collected
from sites running the rtstats(1) utility
are now available for analysis and debugging
The LDM webpages have been updated and also made available as
a separate distribution
During the testing of LDM-6, several factors regarding site performance
were also uncovered as a result of greater throughput. These include:
Performance degredation due to poor regular expression syntax
Operating system tuning parameters related to product queue caching
Additional site education on these issues will be beneficial.
New top-level IDD relay nodes installed at NSF/ATM (Sun SunFire 280R)
and U. Wisconsin (Sun Enterprise 450).
101 unique sites have downloaded the current LDM-6 release.
87 machines at 60 sites are running LDM-6 and
reporting real time statistics. 55 sites currently
running LDM-5 are being encouraged to upgrade to LDM-6 as the
spring semester draws to a close.
10 Unidata members have made use of an offer by the UPC for
a remote LDM-6 installation and tuneup.
The CONDUIT injection host was upgraded to LDM-6 on May 5, 2003.
The current IDD topology is now depicted dynamically from rtstats
reports, rather from hourly summaries mailed in from IDD sites.
As a result, the topology information now reflects changes in feed
requests much sooner than before, and no longer loses information about
sites that haven't reconnected recently.
LDM-6 continues to demonstrate dramatically better
performance than LDM-5. The following plots show the reduction
in product-latency that was seen by an LDM-6 when its upstream
LDM was switched from 5 to 6:
A UPC FreeBSD PC has been proven to be an able host for LDM services.
Its only limitation is lack of support for LDM queues greater
than approximately 4 GB (due to a limitation of the mmap
LDM-6 is being testing as a CRAFT relay node
(Sinclair, Droegemeier, Kelleher). NWS will use LDM-6 to move
NEXRAD Level II data from radar sites to three collection points:
University of Maryland, NCDC, and the University of Oklahoma.
Internet-2 will be used for the data movement.