Header/Self-defining Section

This section contains the common SMF record headers fields and the triplet fields (offset/length/number), if applicable, that locate the other sections on the record.

Offsets		Name	Length	Format	Description
0	0	SMF21LEN	2	binary	Record length. This field and the next field (total of four bytes) form the RDW (record descriptor word). See Standard SMF record header for a detailed description.
2	2	SMF21SEG	2	binary	Segment descriptor (see record length field).
4	4	SMF21FLG	1	binary	System indicator: Bit Meaning when set 0-2 Reserved 3-6 Version indicators* 7 Reserved. *See Standard SMF record header for a detailed description.
5	5	SMF21RTY	1	binary	Record type 21 (X'15').
6	6	SMF21TME	4	binary	Time since midnight, in hundredths of a second, when the record was moved into the SMF buffer.
10	A	SMF21DTE	4	packed	Date when the record was moved into the SMF buffer, in the form 0`cyydddF`. See Standard SMF record header for a detailed description.
14	E	SMF21SID	4	EBCDIC	System identification (from the SID parameter).
18	12	SMF21LGH	2	binary	Length of rest of record.
20	14	SMF21VOL	6	EBCDIC	Volume serial number.
26	1A	SMF21CA	2	binary	Device number or device address.
28	1C	SMF21UCB	4	binary	UCBTYP value.
31	1F	SMF21DEV	1	binary	Low order byte of UCB device type. Values less than X'80' represent reel tapes. Values of X'80' or greater represent cartridge tapes.
32	20	SMF21TR	1	binary	Number of temporary read errors (non-buffered log).
33	21	SMF21TW	1	binary	Number of temporary write errors (non-buffered log).
34	22	SMF21SIO	2	binary	Number of start sub-channel (SSCH) instructions.
36	24	SMF21PR	1	binary	Number of permanent read errors.
37	25	SMF21PW	1	binary	Number of permanent write errors.
38	26	SMF21NB	1	binary	Number of noise blocks (non-buffered log).
39	27	SMF21ERG	2	binary	Number of erase gaps.
41	29	SMF21CLN	2	binary	Number of cleaner actions.
44	2C	SMF21BLS	2	binary	Block size of the last data set closed on the tape if the tape was demounted during CLOSE processing, not at a different time. Some programs that use EXCP do not provide a block size. This field is valid only (but still might contain zero) when bit SMF21LB is off.
46	2E	SMF21OFL SMF21OUT SMF21RDB	1	binary	DCBOFLGS. Bit Meaning 1... .... Output tape .1.. .... Input tape (READ BACKWARD)
47	2F	SMF21TUS	3	packed	Tape unit serial.
50	32	SMF21TRF	2	binary	Temporary read forward errors.
52	34	SMF21TRB	2	binary	Temporary read backward errors.
54	36	SMF21TWF	2	binary	Temporary write errors.
56	38	SMF21BR	3	binary	Number of bytes read, in units of 4096. The length of each block is rounded up to a multiple of 4096 before being counted. This count includes volume mount and verify, in addition to task I/O. Provided only for cartridge tape devices. Maximum value is X'FFFFFF'.
59	3B	SMF21BW	3	binary	Number of bytes written, in units of 4096. The length of each block is rounded up to a multiple of 4096 before being counted. Provided only for cartridge tape devices. Maximum value is X'FFFFFF'.
62	3E	SMF21FL1	1	binary	General flag bytes. Bit Meaning 1... .... Field SMF21NCT, indicating that SMF21BRN and SMF21BWN at 64 and 68 contain valid values. Currently this bit is on only for 3590. .1.. .... Field SMF21LS, indicating that field SMF21LST has a valid value. ..1. .... Field SMF21LB, indicating that SMF21LBS has a valid value. ...1 .... Field SMF21DBV, indicating that SMF21DBR and SMF21DBW at 80 and 84 contain valid values. .... 1... Field SMF21MFV, indicating that SMF21MCR, SMF21MCW, SMF21MDR, and SMF21MDW contain valid values. .... .xxx Reserved.
63	3F	SMF21FL2	1	bit string	Reserved.
64	40	SMF21BRN	4	unsigned binary	Number of bytes read, in units of 4096. The length of each block is rounded up to a multiple of 4096 before being counted. Valid only if SMF21NCT is on. If the value is less than X'FFFFFF', it is also in SMF21BR.
68	44	SMF21BWN	4	unsigned binary	Number of bytes written, in units of 4096. The length of each block is rounded up to a multiple of 4096 before being counted. Valid only if SMF21NCT is on. If the value is less than X'FFFFFF', it is also in SMF21BW.
72	48	SMF21LST	4	unsigned binary	Number of I/Os initiated on current volume. Valid only if SMF21LS is on.
76	4C	SMF21LBS	4	unsigned binary	Block size. Valid only if SMF21LB is on.
80	50	SMF21DBR	4	unsigned binary	Number of bytes read by the device, in units of 4096. Valid only if SMF21DBV is on.
84	54	SMF21DBW	4	unsigned binary	Number of bytes written by the device, in units of 4096. Valid only if SMF21DBV is on.
88	58	SMF21MCR	4	unsigned binary	Number of bytes read by the channel, in units of 1M. Valid only if SMF21MFV is on.
92	5C	SMF21MCW	4	unsigned binary	Number of bytes written by the channel, in units of 1M. Valid only if SMF21MFV is on.
96	60	SMF21MDR	4	unsigned binary	Number of bytes written by the device, in units of 1M. Valid only if SMF21MFV is on.
100	64	SMF21MDW	4	unsigned binary	Number of bytes written by the device, in units of 1M. Valid only if SMF21MFV is on.