SENSE INFORMATION
lC
INTRODUCTION
The storage director provides 24 bytes of sense information ar-ranged in nine error formats. These nine formats are used to classify errors depending upon where they originate and are re-ported. The errors may originate in the channel. storage di-rector. controller. or device.
The nine formats are:' FORMAT
o
1 2 3 4 -5 6 7 8
CONDITION Program or system checks Device equipment checks
Storage director equipment checks Storage director control checks Uncorrectable data checks
Correctable data checks
Usage/overrun error statistics Controller Check-l
Controller equipment checks Check-2. device Check-i)
(controller Of these nine. only Formats O. 1. 4. S. 6. 7. and 8 apply to the controller/device. Figures 1C-i through iC-S provide a summary of the bytes/bits in these formats. Immediately fol-lowing the summaries. each sense byte/bit is further defined by a statement. The remaining formats apply to errors detected and reported by the storage director; refer to the appl icable storage control troubleshooting manual.
FORMAT 0 -- PROGRAM OR SYSTEM CHECKS
Format 0 is composed of all program or system check errors.
These checks occur in the channel or channel side of the chan-nel interface. but are detected by a storage director. Exam-ples are an incorrectly programmed channel routine. a channel problem causing an invalid tag sequence. or a parity error.
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FORMAT 1 -- DEVICE EQUIPMENT CHECKS
Format 1 consists of all device Check-2 errors, which are usu-ally hardware or data checks and can be retried. It is gener-ated when the storage director detects one of the following:
• An end operation response code of 20.
• A Seek Incomplete or Cyl inder Address Miscompare er ror.
When the seek check counter overflows or when in forced logging mode, this error is reported only as Byte 0 Bit 3 (permanent bit is not turned on).
• A failure as defined by the message code in Byte 7.
• An intervention required condition when the addressed de-vice is not attached to the string (End operation re-sponse 09 results in Byte 0, Bit 1 being set by the stor-age director).
FORMAT 4 -- UNCORRECTABLE DATA CHECKS Format 4 lists data checks
(uncorrectable data checks). without displacement information This format is generated when:
• Retry is exhausted for an uncorrectable permanent error.
Byte 0, Bit 4 (Data Check) and Byte I, Bit 0 (Permanent Error) are also set.
• Retry is successful for
a
temporary error with Byte 15 (Offset Level) active. Byte 0, Bit 4 (Data Check) and Byte 2, Bit 3 (Environmental Data Present) are also set.• Retry is successful for a temporary error. A data check temporary error rate counter overflow occurs (nominal data check rate exceeded). Byte 0, Bit 4 (Data Check), Byte I, Bit 3 (Message to Operator), Byte 2, Bit 2 (First Logging Mode Error), and Byte 2, Bit 3 (Environmental Data Present) are also set.
• Retry is successful for a temporary error. Forced Log-ging Mode is set, Byte 0, Bit 4 (Data Check)· and Byte 2, Bit 3 (Environmental Data Present) are also set.
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FORMAT 5 -- CORRECTABLE DATA CHECKS
Format 5 lists data checks with displacement information (cor-rectable data checks). This format is generated when:
• Data checks that are correctable by error correction code (ECC) occurring in a data area. These data checks are not logged even though this format is used to report the checks to the operating system error recovery program
(ERP) .
• Data checks that occur in a Home Address (RA), count. or key area are corrected within the storage director and contain data that is not needed by the system ERP. Cor-rected RA, count, or key area sense data is only trans-mitted to the operating system ERP when logging mode is set to have the data checks logged.
When in logging mode, two Format 5 sense values are presented to the system when there are conditions that require correc-tion. The first value (Byte 2, Bit 3 equals 0) is used by the ERP and is not logged. The second value (Byte 2, Bit 3 equals 1) is not used by the ERP and is logged.
FORMAT 6 -- USAGE/OVERRUN ERROR STATISTICS
Format 6 does not result directly from a fault or check condi-tion. Format 6 sense information is generated after "the chan-nel issues a Read and Reset Buffered Log Command. The channel requests Fo~mat 6 information to prepare a report on device and channel usage or to flag an unusually high number of overru"ns or intermittent failures. A storage director can request the channel to read the log because a counter has overflowed.
FORMAT 7 -- CONTROLLER CHECK-1 Format 7 lists
equipment checks. controller and director-to-device
It is generated when: interface
• A Check-1 error is detected within the controller logic.
• The storage director to controller interface fails in-bound.
• A timer in the storage director overflows while wai ting for a response from the controller.
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• A control interface tag in sequence or a bus parity fail-ure is detected by the storage director.
Check-l logic failures block normal controller communications wi th the storage director. Controller logic errors are col-lected in the connection check shift register and signaled to the storage director by a storage director to controller inter-face connection check alert (CCA). The storage director gath-ers the failure data with a request connection checks (RCC) sequence.
The storage director monitors the storage director-to-device (DDC) interface during the transfer of control signals and re-ports Bus In and Tag In errors. These errors are classed as controller errors and are reported in Format 7 sense data.
Comparable errors in outbound storage director to controller interface control or data signals are classed as storage direc-tor errors.
The storage director microcode times event durations. If the controller exceeds the allotted amount of response time. a mes-sage is generated in Byte 7. The collected sequencer address in the sense data can point to the cause of the time out. . The controller saves the sequencer address whenever a Check-l or Check-2 occurs or when an RCC sequence is initiated. An RCC sequence collects this address and passes it to the storage director along with active controller checks.
FORMAT 8 -- CONTROLLER EQUIPMENT CHECKS
Format 8 is generated when a storage director detects control-ler Check-2 or device Check-l equipment failures. Controller Check-2 conditions do not prevent selection. normal communica-tions on the director-to-device controller interface, or opera-tions of the controller sequencer. Controller Check-2 and device Check-l equipment conditions are reported to the storage director by normal director-to-device controller end operation codes.
SENSE BYTES 0 THROUGH 7
Sense Bytes 0 through 7 are common to all formats (0 through 8). See Figures lC-l through Ie-8.
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BITS REJECT REQUIRED PARITY CHECK CHECK
PERMANENT INVALID END OF MESSAGE TO NO RECORD FILE ZERO ZERO ERROR TRACK CYLINDER OPERATOR FOUND PROTECTED
FORMAT
ZERO CORRECTABLE FIRST LOGGING ENVIRONMENTAL INTENT IMPRECISE ZERO ZERO DATA CHK MODE ERROR DATA PRESENT VIOLATION ENDING
RESTART COMMAND/CONTROLLER PHYSICAL IDENTIFIER**/RESIDUAL RECORD COUNT DPS ZERO PERMANENT RESERVED DEVICE ADDRESS
FUNCTION PATH ERROR 8 I 4 I 2 I 1
LOW-ORDER PHYSICAL CYLINDER ADDRESS
128 64 32 I 16 8 I 4 I 2 I 1
HIGH-ORDER PHYSICAL HEAD ADDRESS ZERO ZERO CYLINDER ADDRESS
DEVICE EQUIPMENT CHECKS SO EQUIPMENT CHECKS ***
SO CONTROL CHECKS ***
MICROCODE DETECTED HARDWARE DETECTED
UNCORRECTABLE DATA CHECKS CORRECTABLE DATA CHECKS USAGE AND ERROR STATISTICS CONTROLLER CHECK-l
CONTROLLER EQUIPMENT CHECKS NOT USED FOR FORMAT 6
NOT USED FOR FORMATS 4 AND 5
SEE FIGURE lC-2
REFER TO APPLICABLE STORAGE CONTROL TROUBLESHOOTING MANUAL
Figure IC-I. Sense Bytes 0 thru 7 Summary
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