6100 BSC Programming Manual

APPENDIX A
FILE SYSTEM ERROR CODES
This appendix lists the file system errors that have special
meanings for CP6100 or the 6100 subsystem. For each error,
it gives the error number, a brief description of the error
and what caused it, and a corrective action you can take.
For descriptions of other file system errors, consult the
NonStop System Messages Manual.
Errors listed under the heading "These are serious. Don't retry"
indicate that something was wrong with the request or the device.
The discussion suggests briefly what to do for each kind of
error.
Errors listed under the heading "Retry these" indicate temporary
resource shortages or path switch conditions. In the first case,
if you repeat the request, it will probably work.
PATH SWITCHES
Recovery from a path switch can be somewhat more complex.
A path switch leaves the line state undefined in some protocols;
regardless of protocol, it's hard to know what data, if any, has
been lost. If you retry a write, you might be sending text for
the second time. If you retry a read, you might not get the data
you were expecting. For example, if the failure occurred after
the data arrived and was acknowledged, but before the data was
delivered to your application buffer, a repeat of the read will
not achieve the desired results; the remote station, having
already received an acknowledgement, sends you its next block or
message, rather than the one you lost. This situation demands
what is sometimes called "end-to-end recovery."
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