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McIDAS-XCD
End-of-year Rollover Addendum
Software and Instructions
21 December 2006
This is the first addendum to the June 2006 McIDAS-XCD upgrade.
If you downloaded the McIDAS-XCD 2006 installation files prior to December
21st, follow the instructions below. If you downloaded the McIDAS-XCD
2006 installation files on or after December 21st, you may disregard
this addendum as the installation files have been modified.
If your site keeps five or more days of real-time MD
or Grid file data online and uses the QRTMDG command to maintain
the cylinders of files, you must install this addendum before
00:00 UTC 31 December 2006.
The addendum contains these two fixes:
- An updated QRTMDG command that contains the logic for correctly handling
end-of-year transitions (from 31 Dec to 01 Jan). Here is an excerpt
of the QRTMDG documentation
that describes how it will work:
QRTMDG works during the transition to a new
year by determining the Julian date of the next day and deleting
the files for that day. For example, running QRTMDG on day 002
will delete files 3, 13, 23,... (which contained day 363 data)
so they can be written when data for day 003 arrives.
Due to the cylinder structure and day numbering during the
transition to a new year (from days ...,364, 365 to 001, 002,...)
there are limits to the number of days of data you can keep online
between days 365 and 008 because, for example, MD file 4 can store
data for day 364 or 004, but not both. During a non-leap year transition
(e.g., 2005-2006), the constraints limit you to a maximum of four
files on day 004; five files on days 003 and 005; six files on
days 002 and 006; seven files on days 001 and 007; and eight files
on days 365 and 008. During a leap year transition (e.g., 2008-2009),
the constraints limit you to five files on days 003, 004 and 005;
six files on days 002 and 006; seven files on days 001 and 007;
and eight files on days 366 and 008.
If you store four or less days of data (five or less
days during leap year transitions), QRTMDG works as expected
because there are no day numbering conflicts. For example,
running QRTMDG each day with a numdays value of
4 retains surface hourly MD files 5, 4, 3, 2 on day 365;
files 1, 5, 4, 3 on day 001; files 2, 1, 5, 4 on day 003,
etc.
- An updated xcdadmin script that fixes a problem in its "stop" option
that prevents it from completely stopping the -XCD session. The
script in this addendum was originally included in the updated
xcd2006.tar.Z file that was made available on the McIDAS Website
on 23 Aug 2006. We are including it with this 21 December 2006
addendum because our records indicate that sites had not yet downloaded
and installed 23 Aug 2006 tar file.
It's important that sites that use the xcdadmin script for starting
and stopping -XCD obtain and use this updated version of the script
because of the bug in previous versions. For more information about
xcdadmin and its use, see the section titled "McIDAS-XCD Administration
Script" in the -XCD 2006 Upgrade Procedure
and the xcdadmin
page in the -XCD manual.
Required Action:
If you are interested in obtaining the changes to QRTMDG and xcdadmin,
follow the steps below.
- As user oper, download the file qrtmdg.pgm to
your ~oper/mcidas/xcd2006/src directory.
- Download the file xcdadmin to
your ~oper/mcidas/xcd2006/data directory.
- Set the McIDAS-XCD environment for compiling.
Type: cd ~oper/mcidas/xcd2006
Type: . ./xcd_init
- Compile the new code.
Type: cd ~oper/mcidas/xcd2006/src
Type: make install.bin
Type: make install.data
- Check that the files have been updated and have today's date.
Type: ls -la ~oper/mcidas/bin/qrtmdg.k
Type: ls -la ~oper/mcidas/bin/xcdadmin
This completes the instructions. If you have any questions, send email
to the McIDAS Help Desk.
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