EXIGN: Restore the CSW from the error queue entry and dequeue the error queue entry. Return to I/o I nterrupt and continue evaluating the CSW.
EXWHY: Retry the user's channel program starting with the CCW in error. Dequeue the error queue entry. Return to I/o Interrupt and re-evaluate the CSW.
EXRTY: Same action as EXIGN if the retry flag is not set in the error queue entry.
If the retry flag is set, dequeue the error queue entry and return to I/o Interrupt to re-schedule the channel.
I/o INTERRUPT
Return to Transient
84 DOS Supervisor and Physical and Logical Transients
Chart 07. Physical Transients (Part 1 of 2)
ERROR RECOVERY PROCEDURE MONITOR Charts lA-LC The ERP monitor consists of three A-transient programs:
I. $$ANERRA .. Determine device type and fetch correct A-transient to perform ERP*. If device type cannot be determinedt fetch
$$ANERRC. If device type is disk, begin identification of unrecoverable errors and continue to $$ANERRB.
2. S$ANERRB .. Continue identification of disk unrecoverable errors and perform ERP for errors detected.
3. SSANERRC .. Insert the reguired message code, turn off the 'retry' and
I ignore I bits in the error queue flog byte, and fetch
$$ANERRM.
* The A-transients that ore fetched for devices other thon disk are:
Pape' Tape DatalCell Op,;,al Reade, Una RrO'd MICR
-+---,
$SANERRG-SIANERRK~
08 DATA CELL ERP Charts LM-LUSSANERRU-
~
SSANERRV
t
UNIT RECORD ERP Chorts MF-MJ
SSANERRT,
\$ANERRW Dato cell error recovery consists of five
A-transient programs:
I. SSANERRG (Phase 1) - Determine type of error and perform ERP for channel data check, equipment check, command reject, intervention required, overrun, end of cylinder, chaining check, and file protect. Fetch
$$ANERRH-$$ANERRJ for other error conditions as indicated.
2. SSANERRH (Phase 2) - Perform ERP for track condition check.
3. $$ANERRI (Phase 3) - Perform ERP for data check and missing address marker.
If 226 retries are exceeded, fetch S$ANERRK.
4. $$ANERRJ (Phase 4) - Perform ERP for no-record-found and seek check.
5. I$ANERRK (Pha,e 5) - Camplete ERP for data check and missing address marker.
SSANERRX
L.,
PAPER TAPE ERP Charts MN,MP Paper tape error recovery consists of one A-transient program that determines the type of error and exits for 1 retry on certain errors bef9re fetching tre me,ssoge writer.$$ANERRD-SIANERRF, $$ANERRL TAPE ERP
-Unit record error recovery consists of two A-transient programs:
1. $$ANERRU (Phase 1) - Check for unsupported devices and cannot-occur conditions, perform ERP for channel data check and 1052.
2. $$ANERRV (Phase 2) - Perform ERP for 1403, 1442, 1443, 2501, 2520, and 2540.
$SANERR9
_ OPTICAL READER ERP Cha,t, MX,MY Optical reader error recovery consists of one A-transient program that determines the type of error and exits for retry or ignore on certain errors for either the 1285 or the 1287.
Charts LD-LL Tape error recovery consists of four A-transient programs:
$$ANERRD (Phase 1) - Determine type of error and perform ERP for read data check, error on recovery, device not operational, and equipment check. Continue at $$ANERRE, $SANERRf, or $$ANERRL, depending on error identification.
$$ANERRE (Phase 2) - Perform ERP for data converter check, drive in backward status at load point, non-compotible condition, channel data check, chaining check, busout, or overrun. Take Ignore exit if operator intervention required after initial selection. fetch
$SANERRL for command reject or $$ANERRA for program or
protection check. $$ANERRA-t----,
$$ANERRF {Iflase 3} - Perform ERP for write and WTM data checks, and perform tape cleaning if command was read. Fetch $SANERRL for unit checks
8
on erase gop command. 1
$SANERRL (Phose 4) - Perform ERP for command reject, data checks that have exceeded 100 retries, and unit checks that occurred on ERG in Phase 3.
NOTE: In general, the error recovery procedures consist of analyzing the sense data bytes and the CSW thot have been stored in the error queue entry (ERQUE), identifying the error, and inserting the selected message code in the ERQUE.
If required, selected error bits are posted in bytes 2 and 3 of the CCB. For certain conditions, such as when a retry is to be mode or an error is to be ignored, bits are posted in the ERQUE flog byte.
See Figure 35 and the subsequent section I/O Error Recovery Procedures and Sense Data for detailed information about sense data for each device. See Figure 33 for an illustration of the error recovery block (ERBLOC), including the error queue entry (ERQUE). Figure 36 is a listing of the hexadecimal message codes with the error message for each code. See Figures 31 and 27 for the condition and error bits in the CSW and CCB, respectively.
Fetch Message Writer
NO 06 ERP Exits
YES
08
$$ANERRM
Charts 85
Chart 08. Physical Transients (Part 2 of 2)
$$ANERRM
~
$$ANERRPcp
MESSAGE WRITER (Pha,. I) Chart LV MESSAGE WRITER (Pha,. 4) Chart LZ
Analyzes message code in Error Queue entry for Prints error message containing inFormation gathered and saved device in error. Selects appropriate lO-byte from previous phosesj prints on 1052 or printer.
message and obtains CCB address - both are stored If an error occurs on SYSLOG while printing the message, up to in save area for use by subsequent phases. three retries are made. The next phase to be Fetched is determined
as a result of one or more conditions:
• Na .rror on SYSLOG, d.c;,;on m .. ,age.
!
+
• No error on SYSLOG, action message and SYSlOG fetch
$$ANERRN is printer. $$ANERRQ
• Error on SYSLOG, decision or information message, MESSAGE WRITER (Ph",. 2) Charts LWr LX and SYSLOG error does not persist after retry. .
·
Error on SYSLOG, decision or information message, fetch Continues preparation of message:~ M~'
- "., ... , .",..
r~w 1. Prepares ACTION field (action, information, or • No error on SYSLOG, information message.decision), TARG 1 field (ignore or cancel), and • ~o error on SYSlOG, action message and SYSlOG fetch TARG2 fi.ld (r.try). TARG I and/or TARG2
fields may be blank, depending on what options •
~rr:rl~~SYSLOG,
action message and error persists $$ANERRSare to be taken. after third retry. J
2. Identifies partition (BG,Fl, or F2) to which the device was assigned.
3. Unpacks the message number.
If SYSLOG is unassigned, phase R is called unless
.~
the message is information only in which case S is called, bypassing intervening phases.
y
S$$ANERRQ
SYSLOG NO
<€r
MESSAGE WRITER (Ph",. 5) Chart, MA-MBAssigned Message
Analyzes operator IS response to message and turns on appropriate flags for use of phase S. Receives
·YES YES operator IS response via the 1052 keyboard. However,
$$ANERRO if operator responds incorrectly, the message
"OPNND INVALID RESPONSE" is printed and MESSAGE WRITER (Pha,. 3) Chart LY phase R is called.
Prepares and saves message information about:
1. Symbolic name of device, e. g., SYSRDR or
~
SYSOOI;
2. CSW;
3. Sense Byte Datai
4. Channel and Unit Number of device; YES
5. Seek address at error time if DASD.
cb
NO
$$ANERRR
MESSAGE WRITER (Pha,e 6) Chart MC If a system-to-operator message could not be printed on SYSLOG for any of severol possible reasons, the console is used to communicate with the operator.
Information is stored for console displ~ as follows:
Byte 0 - message number Byte 1 - Action character (A or D)
wCf
Bytes 2 and 3 - Channel and unit number of error device.
The system is PJt in a wait state pending
$$ANERRT, $$ANERRW operator IS response. Option flags are set for use
MICR ERP Charts ME, MK-MH in Phase 7.
Magnetic Ink Character Recognition devices ERP conststs of two A-transient progroms~
1. $$ANERRT - Check for cannot-occur conditions, determine type of error, and perform ERP for 1412 and 1419 (single address adapter) devices.
2. $$ANERRW - Check for cannot-occur
$$ANERRS conditions, determine type of error, and
perform ERP for 1419 dual address adapter MESSAGE WRITER (Pha,. 7) Chart MD
device. The ERP distinguishes between primary Analyzes the External Option Flags set by the operator IS response and secondary control units and between and chooses the appropriate exit to Cancel, Retry, or Ignore.
stacker-select and pocket light command codes. Here is a sample format of the error messages:
BG OPIBI C COMM REJCT SYS003
=
191 CCSW=
XXXXXXXXXXXXXXXXXX SNS=
XXXXXXXXXXXX CCB
=
XXXXXX SK=
BBBBCCCCHHHH
Fetch Message NO Writer
YES 06
ERP EXITS I
86 DOS Supervisor and Physical and Logical Transients
Chart 09. Physical Attention Transients
02
$$ANERRZ
PHYSICAL ATTENTION Charts MS,MT
This physical transient is used to perform tests whose results determine which A or B-transient is required
for further processing of the attention interrupt.
1. If SYSLOG is not a 1052-exit.---\---, 2. Scan the PUB (Physical Unit Block) for devices
requiring operator intervention.