crash(8)
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crash System Maintenance Procedure
what to do when the DG/UX System crashes
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DESCRIPTION
This entry tells you what to do if the system crashes. Two kinds
of crashes can occur: panics and hangs. A panic, a system-
detected crash, sends a panic message to the operator's console.
A hang, a crash not detected by the operating system, is an
infinite loop or a deadlock.
How to shut the system down
If your system panics, be sure to record the panic number. Then
dump the system memory as described below in Taking System Dumps.
You will automatically enter the system dump dialogue.
If your system halts, type the ``.'' command to the SCP-CLI and
record the accumulator and PC values that are reported. If the
system hangs, hit the BREAK key to get to the SCP-CLI and perform
the same step. Type START 50 to the SCP-CLI, which will put you
into the system dump dialogue. Then take a dump of the system
memory as described below in Taking System Dumps.
Taking System Dumps
If your system panics, you will automatically enter the system
dump dialogue. If the problem is a system halt or hang, you will
have to manually enter the dialogue as described above. The
dialogue will read as follows:
Do you want to take a system dump? [Y]
You will be prompted for the dump device in DG/UX common device
specification format; you can override the default device if
desired:
Dump destination device? [mtb@62(0)]
You will then be prompted to mount a tape:
Mount tape. Type newline when tape is ready.
If the system memory image is too large to fit on one tape, you
will be prompted to load subsequent tape volumes:
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Tape volume 1 completed.
Mount tape. Type newline when tape is ready.
If any tape volume write fails, you will be allowed to restart
the dump at the beginning of that volume:
Hard error on tape volume 1. Restarting volume from checkpoint.
Mount tape. Type newline when tape is ready.
The final volume will be rewound upon completion of the dump:
System dump completed successfully.
In all cases, when you provide a dump, you should also provide a
copy of the tailored system image (usually named /dgux) that was
running at the time of the crash. This image contains vital
information necessary for interpretation of the memory dump; the
memory dump is useless without the system image. See the "DG/UX
System Release Notice" on how to send dumps to Data General.
How to Bring the System Back Up
Before you can reboot your system you will have to make sure the
root file system is consistent. You must use standalone Diskman
to do this. Boot standalone Diskman as follows:
SCP-CLI> BOOT 64
Do you want to override defaults? [n] y <NL>
Do you want to load diagnostics? [n] <NL>
Microcode already loaded. Do you want to reinitialize it? [n] <NL>
System file? [root:dpj@64(0)/dgux] /stand/diskman <NL>
The above example is for a system that has a root logical disk
named ``root'' that is contained on the physical disk
``dpj@64(0)''; your system's parameters may differ. The
``/stand/diskman'' reply indicates that the default logical and
physical disk names should be used and that only the name of the
kernel should be changed, from ``/dgux'' to ``/stand/diskman''.
Diskman will come up in its main menu. Choose option 3, ``File
System Management Menu'', and then choice 2, ``Check a File
System''. Then check your root file system according to the
following dialogue:
Enter the Logical Disk Name: root <NL>
There is no Logical Disk named `root' currently known.
Do you want to register any (more) Physical Disks? [y] <NL>
Enter the Physical Disk specification in DG/UX common
format: dpj@64(0)<NL>
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Physical Disk dpj@64(0) has been registered.
No additional information is required, but you may specify fsck
flags and option if you wish.
Enter the flags and options you want to specify: [ ] <NL>
Fsck will then be run on your root file system. After your root
has been successfully checked, you can exit Diskman and reboot
your system as described in Chapter 3 of Installing and Managing
the DG/UX (Trademark) System.
Interpreting dumps
All file system problems should be taken care of before you try
to look at dumps. Copy the dump into a file such as
/usr/tmp/core. Then execute crash(1M) with the core dump file as
its first argument and the system image name as the second
argument to examine the dump.
SEE ALSO
cp(1), crash(1M), fsck(1M).
Installing and Managing the DG/UX (Trademark) System
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