An example of a report produced by DFHLSCU, for estimating the size of a system log, is shown in Figure 7.
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THE LOGSTREAM CALCULATIONS UTILITY REPORT.
JOURNAL TYPE : system log.
INTERVAL : 000002 minutes.
AKPFREQ : 00299
LOGSNUM : 0010
TRANSDUR : 000003 seconds.
**************** REPORT SUMMARY INFORMATION ****************
SEGMENT 00000001 1
DURATION 00006000 seconds 2
TIME 17:12:52.9 3
DATE 2002.171 4
NUMBER OF BLOCKS : 00000002 5
WRITES PER SECOND : <1 6
AVERAGE RECORD SIZE : 00000065 7
AKP INTERVAL : 00179400 8
TYPE QUANTITY NUMBER OF BYTES 6.4 EQUIVALENT 9
FC 00000000 0000000000000000 0000000000000000
JC 00000000 0000000000000000 0000000000000000
TD 00000000 0000000000000000 0000000000000000
TS 00000000 0000000000000000 0000000000000000
KP 00000000 0000000000000000 0000000000000000
RM 00000001 0000000000000066 0000000000000131
SP 00000009 0000000000000350 0000000000000524
Other 00000000 0000000000000000 *** NONE ***
Total 00000010
From this, an AVGBUFSIZE of 00117 was calculated. 10
**************** REPORT SUMMARY INFORMATION ****************
SEGMENT 00000002 DURATION 00000075 seconds
TIME 18:52:52.6 DATE 2002.171
NUMBER OF BLOCKS : 00000095
WRITES PER SECOND : 00000001
AVERAGE RECORD SIZE : 00000206
AKP INTERVAL : 00000195
TYPE QUANTITY NUMBER OF BYTES 6.4 EQUIVALENT
FC 00000090 0000000000011700 0000000000020520
JC 00000000 0000000000000000 0000000000000000
TD 00000003 0000000000000498 0000000000001461
TS 00000003 0000000000000150 0000000000000588
KP 00000000 0000000000000000 0000000000000000
RM 00000001 0000000000000066 0000000000000131
SP 00000018 0000000000000702 0000000000001050
Other 00000030 0000000000003900 *** NONE ***
Total 00000115
From this, an AVGBUFSIZE of 00302 was calculated.
*******************************************************************************
The end of the JOURNAL data set has been reached.
*******************************************************************************
**************** REPORT SUMMARY CONCLUSIONS **************** 11
The following summary contains the highest workload, based
on the number of blocks written:-
SEGMENT 00000002 DURATION 00000075 seconds
TIME 18:52:52.6 DATE 2002.171
NUMBER OF BLOCKS : 00000095
WRITES PER SECOND : 00000001
AVERAGE RECORD SIZE : 00000206
AKP INTERVAL : 00000195
TYPE QUANTITY NUMBER OF BYTES 6.4 EQUIVALENT
FC 00000090 0000000000011700 0000000000020520
JC 00000000 0000000000000000 0000000000000000
TD 00000003 0000000000000498 0000000000001461
TS 00000003 0000000000000150 0000000000000588
KP 00000000 0000000000000000 0000000000000000
RM 00000001 0000000000000066 0000000000000131
SP 00000018 0000000000000702 0000000000001050
Other 00000030 0000000000003900 *** NONE ***
Total 00000115
From this, an AVGBUFSIZE of 00302 was calculated.
************************************************************
This section applies to CF logstreams:- 12
You are recommended to complete the following definition and use it to
create a suitable structure for this journal logstream:
DATA TYPE(LOGR) REPORT(NO) 13
DEFINE STRUCTURE NAME(LOG_DFHLOG_nnn) LOGSNUM(10)
MAXBUFSIZE(64000) AVGBUFSIZE(302)
In addition, the space required within the Coupling Facility by
such a journal can be specified using the following definition:
DATA TYPE(CFRM) REPORT(NO) 14
STRUCTURE NAME(LOG_DFHLOG_nnn)
INITSIZE(2048) SIZE(3328)
PREFLIST(cf_name) REBUILDPERCENT(1)
The following is a typical definition of a logstream using some
default values, and some calculated from this utility:
DATA TYPE(LOGR) REPORT(NO) 15
DEFINE LOGSTREAM NAME(userid.applid.DFHLOG)
STRUCTNAME(LOG_DFHLOG_nnn)
HIGHOFFLOAD(80)
LOWOFFLOAD(40)
If staging is to be used for this logstream, the following value
is that calculated for the staging data set size. This assumes the worst
case where only this logstream is actively connected to the structure. If
more log streams are to be connected in parallel, then this value should
be replaced by one obtained from dividing it by the number of streams.
STG_SIZE(4155) 16
A recommendation for a suitable initial value of LS_SIZE is given below.
LS_SIZE(13)
************************************************************
This section applies to DASD-only logstreams:- 17
You are recommended to complete the following definition and use it to
create a suitable logstream:
DATA TYPE(LOGR) REPORT(NO) 18
DEFINE LOGSTREAM NAME(userid.applid.DFHLOG)
DASDONLY(YES)
HIGHOFFLOAD(80)
LOWOFFLOAD(40)
STG_SIZE(1010)
MAXBUFSIZE(64000)
LS_SIZE(252)
************************************************************
General information section:-
1) The LS_SIZE parameter specifies (in 4K blocks) the size of the logstream
offload data sets (secondary storage) allocation. If the size parameter is
omitted, and the size is not specified in the SMS (System Managed Storage)
constructs, the size is taken from the ALLOCxx member of SYS1.PARMLIB. The
default value is 2 tracks. Using this default size can lead to an excessive
number of data set allocations. The value specified depends upon the logstream
and the amount of data which is offloaded. For a DFHLOG or DFHSHUNT logstream,
sized so that no data is normally offloaded during offload processing, the
value of LS_SIZE should be between 20% to 25% of the logstream primary storage
capacity.
For user journals and forward recovery logs, LS_SIZE should be large enough
to contain the volume of data written during the critical CICS processing
period of the day, in order to eliminate offload data set allocation delays.
Notes:
1 This indicates the segment of the journal data set on which the utility is operating. Each segment holds journal records made over the period specified in the INTERVAL SYSIN statement, unless it is the final segment (when it contains journal records made between the end of the previous segment and the end of the journal data set).
2 This indicates the time duration covered in the segment. It corresponds to the value on the INTERVAL parameter unless it is the final segment (when it is the time between the end of the previous segment and the end of the data set).
3 This is the time at which the data being analyzed in the segment commenced its generation.
4 This is the date on which the data being analyzed by DFHLSCU was generated. It is of the form yyyy.ddd where yyyy is the year, and ddd is the day within the year.
5 The number of journal blocks contained in the segment is shown here.
6 The average number of journal writes per second is shown here. Where the value is greater than 1, its value is shown as an integer value. Where the value is between 0 and 1, '< 1' is shown, and the estimates calculated by DFHLSCU (if based on this segment of the data set) will be inaccurate. Where it is 0, '0' is shown.
DFHLSCU’s estimates are most accurate when the value for writes per second is high. (The maximum value is 25.)
7 The average size of the records in the interval is shown here.
8 The average time interval between activity keypoints is estimated from the information in the segment. This will only appear in the output if the JNLTYPE is SYSTEM.
9 A section containing information about the specific records type found in the segment is provided. Record types included in this section are those generated by:
The 'QUANTITY' column shows the number of records of each type that was found. The total of the values in this column is given. The 'NUMBER OF BYTES' column shows the number of bytes that these records represent. The '6.4 EQUIVALENT' column shows the number of bytes, as calculated by DFHLSCU, that would be required at CICS Transaction Server for z/OS, Version 3 Release 1 for an equivalent record.
10 For each section, a value of AVGBUFSIZE is calculated.
11 Start of the report’s conclusion. The conclusion informs you which segment contained the most journaling activity and is based on the segment with the highest calculated value for AVGBUFSIZE.
12 Start of the report’s recommendations for log streams that use coupling facility structures.
13 For a CF log stream, the recommended log stream structure definition to be included in your DEFINE STRUCTURE jobs.
14 For a CF log stream, the recommended coupling facility space definition to be edited by you for inclusion in the CFRM policy.
15 For a CF log stream, the recommended log stream definition. Note that the definition assumes that duplexing of data is not required. If duplexing is required, add to the definition:
STG_DUPLEX(YES) DUPLEXMODE(COND)
16 For a CF log stream that uses duplexing, the recommended value for the STG_SIZE attribute on your DEFINE LOGSTREAM job. This is the size of the staging data set required by the log stream. It does not take into account any other log streams that might be connected, at the same time, to the log stream structure. If other log streams are to be connected, you should calculate a value for STG_SIZE based on the value recommended by DFHLSCU, divided by the number of estimated connections.
17 Start of the report’s recommendations for DASD-only log streams.
18 For a DASD-only log stream, the recommended log stream definition.
Additional Note
The AKPFREQ and TRANSDUR information will only appear in the report if the JNLTYPE is SYSTEM. The total value in each summary section is that of the records which are relevant to the calculations that the utility carries out. It does not include records that can never occur in a CICS Transaction Server for z/OS, Version 3 Release 1 journal.