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Source: ASTADS file at the DETAIL timespan
Function: This facility allows the storage administrator to
quickly identify the primary users of resources
critical to the operation of the storage I/O
subsystem. Most performance analysts are familiar
with the 80/20 rule, which states that 20% of your
users are responsible for 80% of the resource
usage on your system. Based on the increasing
demands being made upon storage administrators, it
is most effective to concentrate upon the usage of
the system by its primary users. This facility
allows the storage administrator to select one or
more critical resource measures for which
reporting will be done. The reports produced will
quickly identify primary resource consumers,
giving the storage administrator information about
where tuning activities will produce the best
results.
When potential problems have been detected by the
summary reports or charts in this facility, a
detail report option can be used to provide more
information about the area in question. This will
narrow specific problems down to the individual
hour and data set level, if necessary.
Features: As stated above, a wide variety of data selection
and summarization options are available. Data can
be summarized using one or more nodes of the data
set names, one or more of the CA MICS accounting
fields, or using a user-defined table that relates
data set prefixes with descriptions. Selection
and reporting may also be done by date, hour, and
zone. All of these options provide various views
and levels of detail, making it easy to quickly
identify and isolate problems.
The user is allowed to select the resource
elements that can be used for reporting, because
many different elements are available that measure
storage system activity. Several of these may be
selected in one report run, providing a large
amount of information from a single report
execution.
Output reports from this facility include tabular
reports, printer charts, and color graphic charts.
SMS
Issues: Users creating or modifying their SMS storage
classes and groups must carefully monitor the I/O
load on their existing applications, making sure
that load is distributed so as to provide the
desired performance for critical groups. These
reports will help the user design storage classes
and groups, and will allow the monitoring of
resources after SMS implementation to make sure
the SMS groups are still working correctly. This
continued monitoring is essential, as even
well-tuned groups may change as I/O workloads
fluctuate.
COLUMN DESCRIPTIONS
SYSID
This value appears at the top of each page and
identifies the System Identifier (system) to which
this data applies.
Date
The date during which the measurements shown on
this report were taken. The interval at which
measurements are taken, and the number of data
cycles included in the report will affect the
number of dates that appear in the output.
Hour
If summarization by hour was selected, the hour
during which the measurements on the report were
taken will be displayed.
Zone
If summarization by zone was selected, the CA MICS
zone during which the measurements on the report
were taken will be displayed.
Owner
Represents the group to which the displayed totals
apply. This may be assigned using one or more of
the data set name nodes, one of more of the
CA MICS accounting fields, or using a
user-specified table that associates data set
prefixes with descriptive labels.
Data Columns
A separate data column will appear to the right of
the Owner column. It will contain the measurement
element(s) you have selected from the report
options screen. If multiple elements are
selected, each element will appear on a separate
page A maximum of 50 different owners will appear
on each page, representing the 50 largest users of
the selected element. The report will be sorted
so that the largest users of the resource will
appear first. The label associated with each
possible data column, and a short description of
what each value represents, appears below:
Total I/O Duration
The total duration of all I/O requests issued by
this summary group during this measurement
interval. This represents the sum of IOS queue
time, pending time, disconnect time, and connect
time for all requests in this group.
Total IOS Queue Time
The total amount of time spent by I/O requests in
this summary group waiting on the IOS request
queue to be scheduled.
Total Pending Time
The total amount of time spent by I/O requests in
this summary group in pending status. This
represents the time an I/O request must wait for a
clear path to the intended device.
Total Disconnect Time
The total amount of time spent by I/O requests in
this summary group in disconnect status. This
represents the interval between the time the I/O
request has been passed to the device and the time
the device is ready to transfer data.
Total Connect Time
The total amount of time spent by I/O requests in
this summary group in connect status. This
represents the time that data is actually being
transferred between the device and the processor.
Total I/O Requests
The total number of I/O requests issued by all
users in this summary group during this
measurement interval.
Total RPS Time
The total amount of time spent by I/O requests in
this summary group in RPS status. This represents
the time the request is waiting while the DASD
device is being positioned to the correct sector.
Total Seek I/O Requests
The total number of seek I/O requests issued by
users in this summary group during this
measurement interval. A seek request causes the
read/write head of the DASD device to position
itself at a specified cylinder address.
Average Seek Size in CYLS
The average seek distance, expressed in cylinders,
for each I/O request in this summary group for
this measurement interval. This represents the
average distance the DASD read/write heads had to
move to satisfy the I/O requests for this group.
Average Response Time in Milliseconds
The average time, expressed in millionths of a
second, it took for each I/O request to complete
for the I/Os in this summary group during this
measurement interval.
Total Cache Effective (Hit) Count
The total number of I/O requests for this summary
group during this measurement interval that were
processed by cache, and did not have to access the
DASD device directly.
Total Cache Candidate I/O Requests
The total number of I/O requests for this summary
group during this measurement interval that were
considered to be cache candidates.
Total Non-Candidate I/O Requests
The total number of I/O requests for this summary
group during this measurement interval that were
not considered to be candidates for caching.
Total Tracks Loaded
The total number of tracks loaded into the cache
on behalf of I/O requests in this summary group
during this measurement interval.
Total DFW Tracks Loaded
The total number of tracks loaded into the DASD
Fast Write cache on behalf of I/O requests in this
summary group during this measurement interval.
Total NVS Overflow Count
The total number of times that I/O requests by
this summary group caused the non-volatile storage
(NVS) cache area to become full and overflow
during this measurement interval.
Total Dispatching Exceptions
The total number of dispatching exceptions that
were caused by I/O requests in this summary group
during this measurement interval. A display
exception is caused when excessive delay occurs
getting an I/O dispatched.
Total Dsname Exceptions
The total number of data set name exceptions that
were caused by I/O requests in this summary group
during this measurement interval. A dsname
exception is caused when excessive delay occurs at
the data set level.
Total Path Exceptions
The total number of path exceptions that were
caused by I/O requests in this summary group
during this measurement interval. A path
exception is caused when excessive delay occurs at
the I/O path level.
Total Seek Exceptions
The total number of seek exceptions that were
caused by I/O requests in this summary group
during this measurement interval.
Total Volume Exceptions
The total number of volume exceptions that were
caused by I/O requests in this summary group
during this measurement interval. A volume
exception is caused when excessive delay occurs at
the volume level.
Total Cross-Volume Exceptions
The total number of cross-volume exceptions that
were caused by I/O requests in this summary group
during this measurement interval. A cross-volume
exception is caused when excessive delay occurs at
the volume level, caused by activity from another
system.
Total I/O When Volume Reserved
The total number of I/O requests issued by this
summary group during this measurement interval
when the intended device was reserved by another
user.
ASTEX / TOP RESOURCE CONSUMERS (STGEPF) CA MICS StorageMate ABC CORPORATION -------------------------------------------------- SYSID=SYSA Date=05APR91 Hour=9 -------------------------------------------------- Owner Total I/O Requests SUPPORT 204548 SALES 181906 PAYROLL 151365 FINANCE 75403 DATA-BASE-PROD 40616 SYS-PROGS 10119 CORPORATE 7598 MARKETING 125 DATA-BASE-TEST 7 ---------------------------------------- ------------ HOUR 671687
Figure 4-16. ASTEX / Top Resource Consumers / Summary
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