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Source: ASTAVO file at the DAYS timespan
HARDVA file at the DAYS timespan
Function: This facility allows the Storage Administrator to
monitor key storage indicators related to the
operation of DASD cache control units. While DASD
cache has become an important part of the total
storage hierarchy, the lack of convenient and
powerful reporting tools has made it difficult to
manage this resource. The introduction of ASTEX
data into CA MICS should help correct this
problem, because it gives Storage Administrators
the ability to quickly and easily monitor this
important resource.
Cache-related problems are normally caused by too
many users needing cache resources at the same
time. Detection and correction of these problems
requires the ability to analyze the data are
varying levels of granularity. This facility
allows selection and summarization by specific
dates, hours, and CA MICS zones. Selection can
also be limited to the data for a specific volume,
SMS storage group, ASTEX contention group, or MVS
logical control unit. This type of multi-
dimensional analysis can detect problems that
might otherwise remain hidden.
Features: As stated above, a wide variety of options are
available in terms of data selection and
summarization. These options make it easy to run
several reports at varying levels of detail to
quickly identify and isolate a problem.
Output reports from this facility include tabular
reports, printer plots, and color graphic plots.
When plots are requested, up to nine different
elements can be plotted on the same chart.
SMS
Issues: The ability to select and summarize by an SMS
storage group allows you to monitor and tune your
cache resources and your SMS groups so they
deliver optimum performance. The ability to
summarize the report using a Volume Group Table
allows you to simulate the operation of alternate
storage group definitions. Thus, you can easily
move volumes between storage groups, monitor the
results, and then finally make the change in your
group definitions when the results are acceptable.
COLUMN DESCRIPTIONS
SYSID
This value appears at the top of each page and
identifies the System Identifier (system) to which
this data applies.
Volume
Storage Group
Logical Ctl Unit
Contention Group
The top line of each page also indicates the
summary group to which the values on this report
apply. Depending on the report option chosen,
this summarization will be done by volume, SMS
storage group, MVS logical control unit, or ASTEX
contention group.
Date
Indicates the date for which the reported data
applies. Depending on the summarization option
chosen, the date will appear either as part of the
heading or as the first column of data.
Hour
When summarization by hour is requested, this
indicates the hour to which the reported data
applies.
Zone
When summarization by zone is requested, this
indicates the CA MICS zone to which the reported
data applies.
Other Data Columns
Other printed columns that appear on the report
correspond to the elements you have selected to
monitor. All of the elements you select from the
report options screen with the same letter will
appear on the same report. A brief description of
the possible columns that may appear here, and
what those columns represent, is given below:
Total I/O Requests
The total number of I/O requests received for
this group during this measurement interval.
Candidate I/O Requests
The number of I/O requests received that were
considered to be eligible for caching.
Read I/O Requests
The total number of read I/O requests that
were considered to be eligible for caching.
Read Seq I/O Requests
The total number of read sequential I/O
requests that were considered to be eligible
for caching.
DASD FW I/O Requests
The number of I/O requests received that were
considered candidates for DASD Fast Write
caching.
Cache FW I/O Requests
The Number of I/O requests received that were
considered candidates for Cache Fast Write
caching.
Non-Cand I/O Requests
The total number of I/O requests received
that were not considered to be cache
candidates.
Write I/O Requests
The total number of I/O requests received
that were not considered to be cache
candidates because they were write requests.
Cache Byp I/O Requests
The total number of I/O requests received
that were not considered to be cache
candidates because they requested no caching.
IOS Inhib I/O Requests
The total number of I/O requests received
that were not considered to be cache
candidates because IOS had inhibited them due
to cache activity.
ASTEX Inhib I/O Requests
The total number of I/O requests received
that were not considered to be cache
candidates because ASTEX had inhibited them
due to cache activity.
Other I/O Requests
The total number of I/O requests received
that were not considered to be cache
candidates for reasons other than those
listed above.
Cache Hits Total
The total number of I/O requests that were
successfully processed by cache (cache hits).
Cache Hits Read
The total number of read I/O requests that
were successfully processed by cache (cache
hits).
Cache Hits Rd Seq
The total number of read sequential I/O
requests that were successfully processed by
cache (cache hits).
Cache Hits DFW
The total number of I/O requests that were
successfully processed by DASD Fast Write
cache.
Cache Hits CFW
The total number of I/O requests that were
successfully processed by Cache Fast Write
cache.
Total Tracks Loaded
The total number of tracks loaded into cache
during this measurement interval.
DFW Tracks Loaded
The total number of tracks loaded into DASD
Fast Write cache during this measurement
interval.
NVS Overflow Percentage
The percentage of times that requests for
non-volatile storage exceeded NVS capacity
and caused an overflow condition.
Average Demotion Time
The average amount of time a storage page
stayed in cache memory, before being replaced
by a more active page.
% Hits All I/O
The average percentage of all I/O requests
received that were handled by cache storage.
% Hits Cand I/O
The average percentage of all cache candidate
I/O requests received that were handled by
cache storage.
% Hits Read I/O
The average percentage of all read I/O
requests received that were handled by cache
storage.
% Hits Rd Seq I/O
The average percentage of all read sequential
I/O requests received that were handled by
cache storage.
% Hits DFW I/O
The average percentage of all DASD Fast Write
requests received that were handled by DASD
Fast Write.
% Hits CFW I/O
The average percentage of all Cache Fast
Write requests received that were handled by
Cache Fast Write.
% Demote Time < 30 sec
The percentage of time during this interval
that the average demotion time was less than
30 seconds. Demotion time indicates the
amount of time a page can remain unreferenced
before being removed from cache.
% Demote Time < 1 min
The percentage of time during this interval
that the average demotion time was less than
one minute. Demotion time indicates the
amount of time a page can remain unreferenced
before being removed from cache.
% Demote Time < 2 min
The percentage of time during this interval
that the average demotion time was less than
two minutes. Demotion time indicates the
amount of time a page can remain unreferenced
before being removed from cache.
% Demote Time > 2 min
The percentage of time during this interval
that the average demotion time was greater
than two minutes. Demotion time indicates
the amount of time a page can remain
unreferenced before being removed from cache.
DAILY ASTEX CACHE STATISTICS (STGEPE) CA MICS StorageMate ABC CORPORATION ------------------------------------------- SYSID=SYSA Storage Group=TSOLRG Date=05APR91 ------------------------------------------- Hour Non-Cand Write Cache IOS ASTEX Other I/O I/O Byp I/O Inhib I/O Inhib I/O I/O Requests Requests Requests Requests Requests Requests 0 4709 935 0 3042 257 475 1 53338 16948 0 32549 1450 2391 2 24238 10268 0 10446 1324 2200 3 18880 14069 0 102 3851 858 4 3568 704 0 18 2528 318 5 1000 607 0 38 61 294 6 1902 722 0 10 816 354 7 2077 686 0 36 1026 329 8 7931 4727 0 233 649 2322 9 3465 961 0 761 1303 440 17 2444 902 0 699 358 485 18 1573 754 0 188 271 360 19 2239 1367 0 22 526 324 20 1886 1473 0 6 96 311 21 1047 619 0 20 95 313 22 1041 610 0 0 131 300 23 1048 620 0 0 128 300 ----- ---------- ---------- ---------- ---------- ---------- ---------- DATE 132386 56972 0 48170 14870 12374
Figure 4-21. Daily ASTEX Cache Statistics / Summary
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