| Where allowed to run: All environments (*ALL) Threadsafe: No |
Parameters Examples Error messages |
The Add Disk Watcher Definition (ADDDWDFN) command adds a new Disk Watcher definition to the system. A Disk Watcher definition identifies the performance data that is to be collected during a Disk Watcher collection. A session can be started using the Start Disk Watcher (STRDW) command. A definition is required when starting a new Disk Watcher collection.
Restrictions:
| Top |
| Keyword | Description | Choices | Notes |
|---|---|---|---|
| DFN | Definition | Name | Required, Positional 1 |
| TEXT | Text 'description' | Character value, *BLANK | Optional |
| COLITV | Collection interval | 1-3600, *DYN | Optional |
| ASP | ASP number | Single values: *ALL, *ASPDEV Other values (up to 10 repetitions): 1-255, *SYS |
Optional |
| ASPDEV | ASP device | Name | Optional |
| DSKUNIT | Disk unit identifier | Single values: *ALL Other values (up to 10 repetitions): 1-6047 |
Optional |
| POOLID | Storage pool identifier | 1-64, *ALL | Optional |
| TYPE | Type | *STATS, *ALL, *TRACE | Optional |
| IOTYPE | I/O type | *ALL, *READ, *WRITE | Optional |
| OBJINF | Object information | *NONE, *ALL, *RESIDENT | Optional |
| COLCOND | Collection condition | Single values: *NONE Other values: Element list |
Optional |
| Element 1: Data type | *RESPTIME, *QTIME, *SERVTIME | ||
| Element 2: Relational operator | *LT, *GT, *LE, *GE | ||
| Element 3: Value | Integer | ||
| COLRNG | Collection range | Single values: *NONE Other values: Element list |
Optional |
| Element 1: Data type | *RESPTIME, *QTIME, *SERVTIME | ||
| Element 2: Lower value | Integer | ||
| Element 3: Upper value | Integer | ||
| FRCRCD | Force record write | *ITVEND, *CALC | Optional |
| TOASPTHLD | To file ASP threshold | 1-99, *SYSTEM | Optional |
| SYSASPTHLD | System ASP threshold | 1-99, *SYSTEM | Optional |
| Top |
Specifies the name of the Disk Watcher definition being added. If the specified definition already exists an error condition will occur. This is a required parameter.
| Top |
The text description of the Disk Watcher definition to be added.
| Top |
Specifies the interval between retrieval of disk I/O data.
Note: Disk data is collected from a wrapping flight recorder. If the value specified for this parameter is too large, I/O operations may be missed. The record format for Disk Watcher database file QAPYDWINTI includes a field ('Data missed') which indicates whether I/O operations were missed during the interval.
| Top |
Specifies the auxiliary storage pools for which disk I/O information will be collected. Selected ASPs must be varied on in order for data collection to occur.
Single values
Note: A value must be specified for the ASPDEV parameter if this value is specified.
Other values (up to 10 repetitions)
| Top |
Specifies the independent auxiliary storage pool (ASP) device for which disk I/O information should be collected.
Note: A value must be specified for this parameter if *ASPDEV is specified for the ASP number (ASP) parameter.
| Top |
Specifies the disk units for which I/O information should be collected. Disk unit identifiers from 4001 through 6047 are reserved for independent auxiliary storage pools.
Single values
Other values (up to 10 repetitions)
| Top |
Specifies the main memory storage pool for which disk I/O information should be collected as data is read from disk into memory or written from memory back to disk. This parameter is a value ranging from 1 through 64, where pool 1 is the machine pool, and pool 2 is the base pool. This value also corresponds to the identifier shown on the Work with System Status (WRKSYSSTS) display.
Single values
Other values
| Top |
Specifies the type of disk I/O collection to be performed. This determines the detail level of the data which will be collected.
Note: Disk data is collected from a wrapping flight recorder. If the value specified for the Collection interval (COLITV) parameter is too large, I/O operations may be missed. The record format for Disk Watcher database file QAPYDWINTI includes a field ('Data missed') which indicates whether I/O operations were missed during the interval.
Data for a statistics collection is written to database files QAPYDWRUNI, QAPYDWINTI, and QAPYDWSTAT in the library specified for the Library (LIB) parameter.
Data for a trace collection is written to the database files QAPYDWRUNI, QAPYDWINTI, QAPYDWTRC, and QAPYDWTDER in the library specified for the Library (LIB) parameter. Additionally, data will be written to the database files QAPYDWPGMR and QAPYDWOBJR if *ALL or *RESIDENT is specified for the Object information (OBJINF) parameter.
| Top |
Specifies whether the I/O trace data collected should be limited to a particular type of I/O operation.
Note: This parameter will only limit the collection of I/O trace data. Statistics data will always include all I/O operations.
| Top |
Specifies whether Disk Watcher will gather object and program information, such as the object name and program name, and whether this data collection will be limited to objects and programs which are in resident storage.
During *TRACE collections, Disk Watcher collects information related to the object on which the I/O operation was performed. When this object is in resident storage, the time required to gather the data is relatively small. However, if the object is not in resident storage, there will be a more significant performance impact associated with gathering this information. The same is true when collecting information related to the program or procedure which initiated the I/O operation.
| Top |
Specifies whether the I/O trace data collected should be limited to I/O operations which meet a specified condition.
Note: This parameter will only limit the collection of I/O trace data. Statistics data will always include all I/O operations.
Note: Either a single limiting value may be specified for this parameter or a range may be specified for the COLRNG parameter. You cannot specify values for both parameters.
Single values
Element 1: Data type
Element 2: Relational operator
Element 3: Value
| Top |
Specifies whether the I/O trace data collected should be limited to I/O operations which are within a range of time values.
Note: This parameter will only limit the collection of I/O trace data. Statistics data will always include all I/O operations.
Note: Either a single limiting value may be specified for the Collection condition (COLCOND) parameter or a range may be specified for this parameter. You cannot specify values for both parameters.
Single values
Element 1: Data type
Element 2: Lower value
Element 3: Upper value
| Top |
Specifies when disk I/O data records will be written to the Disk Watcher database files.
| Top |
Specifies the percentage of the auxiliary storage pool (ASP) that contains the Disk Watcher database files which can be used before the collection is forced to end. Because the amount of data collected can be very large, this parameter allows you to limit how much of the ASP is consumed. If the database files exist in the system ASP and values are specified in both this parameter and the System ASP threshold (SYSASPTHLD), the SYSASPTHLD parameter will override the value specified here.
| Top |
Specifies the percentage of the system auxiliary storage pool (ASP) which can be used before the collection is forced to end. Because Disk Watcher allocates temporary storage and the amount of data collected can be very large, this parameter allows you to limit how much of the system ASP is consumed. If the database files exist in the system ASP and values are specified in both this parameter and the To file ASP threshold (TOASPTHLD) parameter, the value specified here will take precedence.
| Top |
Example 1: Add a Disk Watcher Definition Which Collects Data for Specific ASPs
ADDDWDFN DFN(ASPNBR) ASP(2 16) TYPE(*STATS) COLITV(5)
This command will create a Disk Watcher definition called ASPNBR. This definition will collect summarized statistics data for auxiliary storage pool (ASP) 2 and ASP 16. Data will be collected at an interval of 5 seconds and will include all I/O operations which occur in the specified ASPs. To collect Disk Watcher data using this definition use the Start Disk Watcher (STRDW) command with ASPNBR specified for the Definition (DFN) parameter.
Example 2: Add a Disk Watcher Definition Which Collects Data for a Specific Disk Unit
ADDDWDFN DFN(DSKNBR) ASP(*SYS) DSKUNIT(12) TYPE(*ALL)
This command will create a Disk Watcher definition called DSKNBR. This definition will collect data for disk unit 12 in the system auxiliary storage pool (ASP). Both detailed trace data and summarized statistics data will be collected. To collect Disk Watcher data using this definition use the Start Disk Watcher (STRDW) command with DSKNBR specified for the Definition (DFN) parameter.
Example 3: Add a Disk Watcher Definition Which Traces Only I/O Operations Which Meet a Collection Condition
ADDDWDFN DFN(RESPTIME) COLTYPE(*TRACE)
COLCOND(*RESPTIME *GT 100)
In this example, a Disk Watcher definition called RESPTIME will be created. This definition will collect data for all ASPs on the system and only trace data will be collected. The I/O operation data collected for the trace will include only those disk operations whose total response time was greater than 100 microseconds. To collect Disk Watcher data using this definition use the Start Disk Watcher (STRDW) command with RESPTIME specified for the Definition (DFN) parameter.
Example 4: Add a Disk Watcher Definition Which Traces Only I/O Write Operations
ADDDWDFN DFN(WRITEOPS) TYPE(*TRACE) IOTYPE(*WRITE)
In this example, a Disk Watcher definition called WRITEOPS will be created. This definition will collect data for all ASPs on the system. Only trace data for I/O operations which write disk data to storage will be collected. To collect Disk Watcher data using this definition use the Start Disk Watcher (STRDW) command with WRITEOPS specified for the Definition (DFN) parameter.
| Top |
*ESCAPE Messages
| Top |