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0 Ref. B5
0 NCP : STATISTICS AND LOGGING (Ref. B5)
+ ___ __________ ___ _______ ___ __
0 Version 2
+ _______ _
0 8 March 1982
+ _ _____ ____
0 P M Girard
+ _ _ ______
0 1. Introduction
+ ____________
0 This paper relates specifically to the VM version of NCP.
The MVT version uses SMF for statistics collection, and
handles the logging disc in a somewhat different way.
0 A CMS-compatible minidisk is used, formatted entirely in
4096-byte blocks. Blocks 1 to 15 are used for statistics
and the rest for logging. The total size of the minidisk
is currently 360 blocks.
- 2. Statistics
+ __________
0 Blocks 1 to 7 and 8 to 14 provide storage for 2 weeks of
statistics, each day having its own 4096-byte block.
0 Monday always uses block 1 or block 8, Tuesday uses block
2 or block 9, and so on.
0 Week numbers are calculated with reference to the clock
base: i.e: 1st January 1900 (which was a Monday). The
first week of January 1900 was week zero_.
+ ____
0 Even-numbered weeks use blocks 1 to 7; odd-numbered weeks
use blocks 8 to 14 (even if there are missing weeks due to
computer shutdown, etc).
0 Block 15 is used as a control record. Only the first 10
words of it are currently defined, the rest of the block
being liable to contain rubbish.
0 The minidisk may be completely re-initialised by running
the DEFILOG procedure. This fills all the blocks with
zeros and this is recognised as a valid situation by NCP,
by the statistics analysis program, and by the log
printing program.
0 When in use, the control block has the following defined
contents:
0 Word 0 : Latest week no. for which statistics are
held.
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- NCP : STATISTICS AND LOGGING PAGE 1
1
0 Ref. B5
0 Word 1 : Latest day no. for which statistics are
held.
0 Word 2 : Latest period no. for which statistics
are held.
0 Words 3-5 : Latest date (day/month/year) for
which statistics are held.
0 Words 6-9 : Zeros. Reserved for future use.
0 The 'day no.' is relative to 1st January 1900 counting
from zero. The 'period no.' is the period no. (currently
2-hour periods are used) relative to midnight, the period
from midnight to 2 a.m. being period zero.
0 At the beginning of a new week, all the blocks for the new
week are re-initialised by filling them with zeros except
the first word of each, which contains the new week
number. The first block is also provided with the current
date in day/month/year form, but it should be noted that
this is not necessarily the correct date for that day, for
instance if the machine was not in use on Monday but
started up on Tuesday.
0 The block used by each day is called a 'day-block' and has
the following structure:
0 Word 0 : Week number.
0 Word 1 : Day number
0 Word 2 : Most recent period number for which
statistics are present.
0 Words 3-5 : Date (day/month/year)
0 Words 6-9 : Spare
0 Word 10 onwards : Accumulations
0 As previously stated, a newly initialised day-block
contains zeros apart from the week number and (in the case
of Mondays only) the date on which the initialisation took
place.
0 The accumulations are arranged as follows. The day is
divided into periods (currently 12 periods), and various
+ _______
totals (currently 7 totals, such as CALLS, PACKETS, etc)
+ ______
are kept for a number of protocols (currently 11
+ _________
protocols) within each period. Each accumulation requires
one word.
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0 NCP : STATISTICS AND LOGGING PAGE 2
1
0 Ref. B5
0 Thus the accumulations part of the block can be considered
to form a FORTRAN array with a structure as follows:
0 INTEGER IACCUM (totals, protocols, periods)
0 The STATS process in NCP is written so that it is harmless
to make it dispatchable at any time. For instance it may
be posted during termination procedures to ensure that no
statistics are lost. Normally the process sets a timer
that should expire 5 seconds past each quarter-hour. The
5-second margin eliminates all risk of an early posting
due to rounding errors in calculating the interval.
0 On the first entry to STATS, the control record is read.
If the current time information implies that some
statistics have already been recorded for the current day,
the day-block is read into core and accumulations resume
from that base. Otherwise the day-block (or if
appropriate, day-blocks for the whole week) is
initialised. The control block is updated if necessary
0 On subsequent entries, totals accumulated by NCP are added
into the day-block, at the period set up during the
previous entry, and NCP's totals are cleared. Everything
is then set up ready for the same thing to take place
after the next posting.
0 If a disc error occurs, statistics cease to be taken, and
a message is sent to the operator's console every so
often. Resumption of taking statistics cannot occur
without a program re-load, but this is a situation which
should in practice never or only very rarely occur.
0 The statistics for the previous or current week can be
printed off by means of the NSTAT procedure (Ref. F1).
- 3. Logging
+ _______
0 The logging part of the minidisk is used cyclically, and
should have enough room for several days of normal
logging. The NLOG procedure (Ref. F1) can be used to
print off the most recent 1000 lines or so from the log,
or to print off any range of blocks quoted explicitly.
The LOGINDX procedure (Ref. F1) can be used to obtain an
index of the log. When diagnostic printing is switched
on, the log will of course fill up much more rapidly than
usual. Failure to print the log has no consequences apart
from loss of the information when NCP begins its next
cycle round the file.
0 Logging information is stored in 56-byte records, of which
up to 73 will fit into a 4096-byte block. The data is
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NCP : STATISTICS AND LOGGING PAGE 3
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0 Ref. B5
0 encoded in a special format which cannot be printed
directly. The NLOG procedure interprets the data and
converts it to printable form.
- 4. References
+ __________
0 F1: VMNCP : Operators' Documentation
(P M Girard)
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