Miscellaneous data (MDR) record

MDR records are recorded on the logrec data set for buffered log devices when the following conditions occur:

Buffer overflow in a buffered log device
Demount of a device
Device failure
Operator-initiated end of day (EOD), record on demand (ROD), or VARY OFFLINE commands
Invocations of EREP that force the writing of statistical data

An MDR record is also recorded on the logrec data set for device failures on teleprocessing devices connected to an IBM® 3704, 3705, or 3725 Communication Controller.

The buffered log devices (devices attached to a control unit with a buffer for recording or logging device-dependent, status and sense information) are listed in offset 26 of the MDR record format (Table 1).

Table 1. Format of the MDR record
Offset		Size (bytes) alignment (bits)	Field name	Description
Dec	Hex	Size (bytes) alignment (bits)	Field name	Description
0	(0)	1	MCLASRC	Class/Source:
		1..1 ....		MDR record formatted by SVC 91; type=X'90'.
		1..1 ...1		MDR record; type=X'91'.
1	(1)	1	MSYSREL	System/Release level:
		100. ....		OS/VS2.
		bits 3-7
		0-1F		Release level 0 through 31.
2	(2)	4	MSWITCHS	Record switches:
		Byte 0
		1... ....		More records follow.
		0... ....		Last record.
		.1.. ....		Time-of-day (TOD) clock instruction issued. Used in conjunction with date and time values at displacements 8 and 12.
		..1. ....		Record truncated. (Not used for MDR record.)
		...1 ....		Record created by MVS/SP Version 2, 3, or 4.
		.... 1...		TIME macro used.
		.... .xxx		Reserved.
		Byte 1
		x... ....		Not used by MDR record.
		.1.. ....		Record incomplete.
		..xx xxxx		Not used by MDR record.
		Byte 2
		Byte 3
		1... ....		Variable length sub-ID field used by record.
		.xxx ....		Reserved.
		bits 4-7		Number of characters in sub-ID field of device identified at
				displacement 26.
6	(6)	1	MRCDCNT	Record count:
		bits 0-3		Sequence number of this physical record.
		bits 4-7		Total number of physical records in this logical record.
7	(7)	1	MCHPID	Channel path identifier.
8	(8)	4	MDATE	System date of incident.
12	(C)	4	MTIME	System time of incident.
16	(10)	1	MVERNO	Machine version code.
17	(11)	3	MCPUSER	Central processor serial number.
20	(14)	2	MCPUMOD	Central processor machine model number.
22	(16)	2	MCELLNG	Reserved.

				END OF STANDARD HEADER

24	(18)	2	BUFRECID	Device number of data identified in this record.
26	(1A)	variable	BUFSUBID	Identification field (2-15 bytes) to identify device at displacement 24. Length of this field (2-15 bytes) is defined at displacement 5. Note: Depending on device, field can denote serial number or CUA of unit.
		variable	BUFINFO	Device-dependent information supplied by ERP that detected error.
		2	MRCTWD	Flag bytes from the RCT used to create this record if the new OBR/MDR interface was used.