Recommended Recovery Procedures - Xerox 7240 Reference Manual

Table 10. Recommended Recovery Procedures
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Recovery
!
Procedure
I
Number
Description
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l Abort - Operator lnterventi on.
All operations on the device must be aborted and operator notification glven that the device is either not
operational or unavailable or the controller is in the test mode. The
op~rator
must then perform action
to return the device to the operational state.
!
l
!
2
Order Retry - Program Recovery.
An HIO instruction should be issued (in the case of controller and/or device not ready) and the operation
retried. This sequence should be retried ten times before considering
th~
operation irrecoverable.
l
3
Order Retr}::'. After Restore - Program Recovery.
1
An HIO instruction must be issued (in the case of controller and/or deviqe busy) followed by a Restore
operation to reestablish head positional reference. A Seek operation shquld then be issued followed by
the operation previously in error (if not a Seek operation). This
sequenc~
should be retried ten times
before considering the failure irrecoverable.
t
4 Order Retry After Seek - Program Recovery.
An HIO instruction should be issued (in the case of controller and/or dejice not ready) followed by a
Seek operation to reestablish the surface address and head position. The
1
operation in error is then retried.
This sequence should be retried ten times before considering the failure ilrrecoverable.
5
Alternate Surface Selection - Program Recovery.
A Header Read operation is performed to determine the assigned alternate surface address. This recovery
is appropriate only when the header area is used for alternate assignment. Whenever a flaw mark is
detected, a Header Read operation must be performed to differentiate be I-ween flawed sectors (only flaw
mark set) and hardware problems (other fault indicators set).
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6 Program Notification - No Recovery Required.
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The program is notified of the following conditions for which recovery islnot necessarily required:
l.
A header flaw marker has been detected during a Header Read or Sejnse operation.
2.
An incorrect length indication appears following an operation for which partial information
transfer is acceptable.
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IRRECOVERABLE ERRORS application. For
exa~ple,
in the case of sense failures,
If a particular fault condition persists after performing the
recommended recovery procedure, the foul t is irrecover-
able. Specific action to be taken after an irrecoverable
fault will vary with the order and with the user's
the system may
tolerat~
such errors, whereas read failures
may require a range ofiaction such as job abortion to shut-
ting down the system.
I
On the other hand, irrecoverable
write operations may
r~quire
the choosing of another surface
area and the flawing ot the failing surface.
1/0
F~ults
and Recovery Procedures 29