Specifications

98 IBM System z Personal Development Tool: Volume 3 Additional Topics
If a problem incident is opened through your IBM Business Partner, you may be requested to
send additional files. In general, once a problem incident is opened, you should not delete
anything from the logs directory.
If device managers fail they automatically create a trace file and are automatically restarted.
This restart will not occur more than three times per minute. If a fourth failure occurs within
the same minute the device manager is not restarted and the devices it controls become not
operational for the remainder of that 1090 session. The 1090 limits the size of the logs and
traces and should never create more than about 30 MB per emulated device (and there is
normally much less than this).
8.3 Core images
Severe problems may cause core image files to be created. If these are created by the 1090,
they should go into the log subdirectory and be cleaned up with --clean option of awsstart. If
you are actively working on a problem with IBM, these files may be useful. Otherwise they
should be deleted because they can be rather large and might create a disk space problem.
Consistent dumps (“core images”) when the 1090 is started can occur if you have a relatively
large number of emulated I/O devices (more than 100, for example) and you have not
considered memory management adjustments. See 1.13, “Devices, memory, msgmni, ulimit”
on page 12 for more information.
The snapdump command is used when the 1090 is running. If you are unable to start the 1090
(with the awsstart command) or the 1090 ends immediately (before a snapdump can be
taken), the problem may have created a core image file. In this case, the core image may help
with problem analysis and should be preserved while the problem is under investigation.
8.4 Emulated volume problems
An emulated 3390 volume is a single Linux file that was created with the alcckd command.
Three variations of this command are useful for problem handling:
$ alcckd /z/WORK03 -rs scan emulated volume for format errors
$ alcckd /z/WORK03 -rf replace bad track with zeros
$ alcckd /z/WORK03 -r display volser and size
The -rs function scans the emulated volume and verifies that it is in the correct 1090
emulation format.
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The -rf function replaces improperly formatted tracks with a properly
formatted track containing zeros. The original contents of the track are lost, but the
functionality of the volume is maintained.
Assuming that your emulated 3390 volumes are in the /z directory and there are no other file
types in this directory, you could verify the format of all the volumes with the following Linux
shell commands:
$ cd /z (location of emulated ckd, and nothing else)
$ for i in *; do alcckd $i -rs; done
The ckdPrint command can be used to examine the contents of an emulated CKD volume.
This command prompts for the beginning cylinder and head numbers and the ending cylinder
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Only the emulation format is checked. There is no check for data content or operating system metadata (label,
VTOC, and such).