crash.8v

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)crash.8v	3.1	11/24/87
.TH crash 8v RISC
.SH Name
crash \- what happens when the system crashes
.SH Description
.NXR "crash keyword"
.NXR "system crash"
This section explains what happens when the system crashes and shows
how to analyze crash dumps.
.PP
When the system crashes voluntarily it prints a message
on the console in the form:
.IP
panic: explanation
.PP
The system takes a dump on a mass storage peripheral device or
the network, and then invokes an automatic reboot procedure as
described in
.MS reboot 8 .
Unless there is some unexpected inconsistency in the state
of the file systems due to hardware or software failure, the system
then resumes multi-user operations.
If auto-reboot is disabled, the system halts at this point.
.PP
The system has a large number of internal consistency checks; if one
of these fails, it prints a short message indicating
which one failed.
.PP
The most common cause of system failures is hardware failure.  
In all cases there is the possibility that hardware or software
error produced the message in some unexpected way.  These 
messages are the ones you are likely to encounter: 
.NXR "system crash" "error messages"
.TP 5
.B IO err in push
.ns
.TP
.B hard IO err in swap
The system encountered an error when trying to write
to the paging device
or an error in reading critical information from a disk drive.
Fix your disk if it is broken or unreliable.
.TP
.B timeout table overflow
.ns
Due to the current data structure, 
running out of entries causes a crash.
If this happens, make the timeout table bigger.
.TP
.B Exception Condition
An unexpected system error has occurred.  The exception types are
as follows:
.PP
.RS 5
.TS
.tab (@);
lfHB lfHB
lfR lfR .
_
.sp 4p
Mnemonic@Description
.sp 4p
_
.sp 6p
INT@External interrupt
MOD@TLB modification exception
TLBL@TLB miss exception (load or instruction fetch)
TLBS@TLB miss exception (store)
AdEL@Address error exception (load or instruction fetch)
AdES@Address error exception (store)
IBE@Bus error exception (for an instruction fetch)
DBE@Bus error exception (for a data load or store)
Sys@Sys call exception
Bp@Breakpoint exception
CpU@Coprocessor unusable exception
Ovf@Arithmetic overflow exception
.sp 6p
_
.TE
.RE
.TP
.B KSP not valid
.ns
This indicates either a problem in the system or 
failing hardware.
.TP
.B init died
The system initialization process has exited.  The only solution is the
automatic reboot procedure described in
.MS reboot 8 . 
Until this is done, new users cannot log in.
.PP
When the system crashes, it attempts to write 
an image of memory into the back end of the primary swap
area.  After the system is rebooted, the program
.MS savecore 8
runs and preserves a copy of this core image and the current
system in a specified directory for later access.  See
.MS savecore 8
for details.
.PP
To analyze a dump, you should begin by running
.MS dbx 1
with the 
.PN \-k
flag on the core dump.
.NXR "crash dump" "analyzing"
.SH See Also
dbx(1), reboot(8), savecore(8)