| Where allowed to run: All environments (*ALL) Threadsafe: No |
Parameters Examples Error messages |
The Start Disk Watcher (STRDW) command starts the collection of disk performance data. It allows the user to obtain data including counts and durations of input/output (I/O) operations to disk units. In addition, it provides useful run-time data regarding which objects are being read from disk or written to disk, and which jobs, threads, or LIC tasks are causing the operations. The collected data is written to a set of database files. The file names all begin with the letters 'QAPYDW'.
Restrictions:
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| Keyword | Description | Choices | Notes |
|---|---|---|---|
| DFN | Definition | Name, *SELECT | Optional |
| COL | Collection | Name, *GEN | Optional |
| LIB | Library | Name, QPFRDATA | Optional |
| TEXT | Text 'description' | Character value, *DFN, *BLANK | Optional |
| RPLDTA | Replace data | *NO, *YES | Optional |
| COLITV | Collection interval | 1-3600, *DFN, *DYN | Optional |
| ENDCOL | End collection | Values (up to 3 repetitions): Element list | Optional |
| Element 1: Option | *NBRSEC, *DASDMB, *NBRITV | ||
| Element 2: Value | Integer, 60 | ||
| HDWF | Hardware file | *YES, *NO | Optional |
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Specifies the Disk Watcher definition to use when starting a new Disk Watcher collection. The definition identifies the disk I/O data to be collected. A new Disk Watcher definition can be created using the Add Disk Watcher Definition (ADDDWDFN) command.
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Specifies the name of the collection. The name of the collection is the name of the database file member to which the output data is to be written. If a member by this name does not exist in each Disk Watcher database file, one will be created with the specified name. If a member by this name already exists, you must specify *YES on the Replace data (RPLDTA) parameter in order to write over the data in the existing member.
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Specifies the library where the database files for the Disk Watcher data are to exist. Each file that is not found in the specified library is automatically created in that library.
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Specifies the text to be used for each member across the set of Disk Watcher database files associated with the collection.
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Specifies whether an existing set of Disk Watcher database file members should be replaced with a new set of members with the same name.
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Specifies the interval between retrieval of disk I/O data.
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Specifies the criteria which will end the collection. This parameter allows you to specify multiple conditions which will end the collection of data. If more than one ending criteria is specified, disk I/O data collection will end the first time any one of specified criteria has been met.
You can specify 3 values for this parameter.
Element 1: Option
Element 2: Value
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Specifies whether data will be written to the QAPYDWHDWR file for this collection. This file contains storage device resource information provided by the Display Hardware Resources (DSPHDWRSC) command.
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Example 1: Start a Disk Watcher Collection
STRDW DFN(MYDFN) COL(TEST) LIB(MYLIB)
This command will start Disk Watcher using definition MYDFN to determine which data should be collected. Assuming the shipped default of ENDCOL(*NBRSEC 60) is used, data collection will end after 60 seconds. Collected data will be written to the Disk Watcher database files in library MYLIB in member TEST. The Disk Watcher database file names all begin with 'QAPYDW'.
Example 2: Start Disk Watcher Using a Collection Interval
STRDW DFN(MYDFN) COLITV(5) ENDCOL((*NBRITV 200))
This command will start Disk Watcher to collect data using the definition called MYDFN. Data will be collected at an interval of 5 seconds, overriding the interval specified in the definition. Data collection will end after 200 intervals have been collected. Data will be written to the Disk Watcher database files in library QPFRDATA in a member name which will be generated by Disk Watcher based on the date and time the collection started.
Example 3: Start Disk Watcher, Prompting to Select a Definition
STRDW DFN(*SELECT) COL(TEST) LIB(MYLIB)
ENDCOL((*DASDMB 100))
This command will open a prompt panel listing all Disk Watcher definitions which currently exist on the system. The definition selected on this panel will be used to determine what data will be collected. Data collection will end after 100 megabytes of data have been written to the Disk Watcher database files in library MYLIB in member TEST.
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*ESCAPE Messages
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