This database file includes disk file entries and contains one record for each disk resource.
Typically, there is one disk resource per disk unit except for a multipath disk unit that has multiple disk resources associated with it.
| Field Name | Description | Attribute |
|---|---|---|
| INTNUM | Interval number: The nth sample database interval based on the start time specified in the Create Performance Data (CRTPFRDTA) command. | PD (5,0) |
| DTETIM | Interval date (yymmdd) and time (hhmmss): The date and time of the sample interval. | C (12) |
| INTSEC | Elapsed interval seconds: The number of seconds since the last sample interval. | PD (7,0) |
| IOPRN | IOP resource name | C (10) |
| DIOPID | Reserved | C (1) |
| DSARM | Disk arm number: Specifies the unique identifier of the unit. Each actuator arm on the disk drives available to the machine represents a unit of auxiliary storage. The value of the unit number is assigned by the system when the unit is allocated to an auxiliary storage pool. | C (4) |
| DSTYPE | Disk drive type such as 9332, 9335, or 6100. | C (4) |
| DSDRN | Device resource name. Typically, there is one disk (device) resource per disk unit except for a multipath disk unit that has multiple disk resources associated with it (see note 5). | C (10) |
| DSSCAN | Number of search string commands: This count is zero for drive types which do not support search string commands. | PD (5,0) |
| DSBLKR | Number of blocks read: Block is one sector on the disk drive. | PD (11,0) |
| DSBLKW | Number of blocks written: Block is one sector on the disk drive. | PD (11,0) |
| DSIDLC | Processor idle loop counter (see note 1): The number of times the disk controller passed through the idle loop. This field is zero for drive types which do not have a dedicated disk processor.
DSIDLC and DSIDLT are duplicated across all units attached to the same disk controller. | PD (11,0) |
| DSIDLT | Processor idle loop time (see note 3): The time (in hundredths of microseconds) to make one pass through the idle loop. This field is zero for drive types which do not have a dedicated disk processor. The value reported could be a multiple of the actual idle loop time. In that case, the value reported for the processor idle loop count field (DSIDLC) is reduced accordingly so that the calculated processor utilization is correct.
DSIDLC and DSIDLT are duplicated across all units attached to the same disk controller. | PD (11,0) |
| DSSK1 | Number of seeks > 2/3: The number of times the arm traveled more than 2/3 of the disk on a seek. | PD (11,0) |
| DSSK2 | Number of seeks > 1/3 and < 2/3 (see note 2): The number of times the arm traveled more than 1/3 but less than 2/3 of the disk on a seek. | PD (11,0) |
| DSSK3 | Number of seeks > 1/6 and < 1/3 (see note 2): The number of times the arm traveled more than 1/6 but less than 1/3 of the disk on a seek. | PD (11,0) |
| DSSK4 | Number of seeks > 1/12 and < 1/6 (see note 2): The number of times the arm traveled more than 1/12 but less than 1/6 of the disk on a seek. | PD (11,0) |
| DSSK5 | Number of seeks < 1/12 (see note 2): The number of times the arm traveled from its current position but less than 1/12 of the disk on a seek. | PD (11,0) |
| DSSK6 | Number of zero seeks (see note 2): The number of times the access arm did not physically move on a seek request. The operation may have resulted in a head switch. This field is 0 for disk drive type 6100. The number of zero seeks will be accumulated in DSSK5. | PD (11,0) |
| DSQUEL | Total queue elements: The number of I/O operations waiting service at sample time. This number includes the I/O operation that is in progress. Divide this by DSSMPL to get the average queue length. | PD (11,0) |
| DSNBSY | Number of times arm not busy: The number of times there were no outstanding I/O operations active at sample time. | PD (11,0) |
| DSSMPL | Number of samples taken: The number of samples taken for the DSQUEL and DSNBSY fields. | PD (11,0) |
| DSCAP | Drive capacity (in bytes): Total number of bytes of auxiliary storage provided on the unit for the storage of objects and internal machine functions when the auxiliary storage pool containing it is not under checksum protection. The unit reserved system space value is subtracted from the unit capacity to calculate this capacity. | PD (15,0) |
| DSAVL | Drive available space (in bytes): Total number of bytes of auxiliary storage space that is not currently assigned to objects or internal machine functions, and therefore is available on the unit. | PD (15,0) |
| DSASP | Auxiliary storage pool number: Specifies the auxiliary storage pool to which this unit is currently allocated. A value of 1 specifies the system auxiliary storage pool. A value from 2 through 32 specifies a basic auxiliary storage pool. A value from 33 to 255 specifies an independent auxiliary storage pool. A value of 0 indicates that this unit is currently not allocated. | PD (5,0) |
| DSCSS | Reserved | C (2) |
| DSPCAP | Reserved | PD (11,0) |
| DSPAVL | Reserved | PD (11,0) |
| DMFLAG | ' ' means this arm is not locally mirrored. 'A' means this is the designated first arm of a locally mirrored pair. 'B' means this is the designated second arm of a locally mirrored pair. | C (1) |
| DMSTS | Local mirroring status. 1 = active, 2 = resuming, 3 = suspended | PD (1,0) |
| DMIRN | Locally mirrored IOP resource name | C (10) |
| DMDRN | Locally mirrored device resource name | C (10) |
| DSRDS | Number of read data commands. | PD (11,0) |
| DSWRTS | Number of write data commands. | PD (11,0) |
| DSBUFO | Number of buffer overruns: The number of times that data was available to be read into the disk controller buffer from the disk, but the disk controller buffer still contained valid data that was not retrieved by the storage device controller. Consequently, the disk had to take an additional revolution until the buffer was available to accept data. | PD (11,0) |
| DSBUFU | Number of buffer underruns: The number of times that the disk controller was ready to transfer data to the disk on a write, but the disk controller buffer was empty. The data was not transferred in time by the disk IOP to the disk controller buffer. The disk was forced to take an extra revolution awaiting the data. | PD (11,0) |
| DSMDLN | Model Number: The model number of the disk drive. | C (4) |
| DSDCRH | Device cache read hits: The number of times that all of the data requested by the read operation was obtained from the device read or write cache. | PD (11,0) |
| DSDCPH | Device cache partial read hits: The number of times that a portion, but not all, of the data requested by the read operation was obtained by the device read or write cache. A physical operation to the device media was required to obtain the remaining data. | PD (11,0) |
| DSDCWH | Device cache write hits: The number of times that the data associated with a write operation replaces, or is combined with, existing data in the device write cache, thereby eliminating a write operation. | PD (11,0) |
| DSDCFW | Device cache fast writers: The number of times that space was available in the device write cache for the data associated with a write operation and a response was returned immediately. | PD (11,0) |
| DSDROP | Device read operations: The number of read operations issued to the device by the controller. This includes operations generated by controller for data protection (RAID) or data compression. This does not include operations generated for diagnostics and operations to access the controller reserved area that occur during this idle time. | PD (11,0) |
| DSDWOP | Device write operations: The number of write operations issued to the device by the controller. This includes operations generated by controller for data protection (RAID) or data compression. This does not include operations generated for diagnostics and operations to access the controller reserved area that occur during this idle time. | PD (11,0) |
| DSCCRH | Controller cache read hits: The number of times that all of the data requested by the read operation was obtained from the controller read or write cache. | PD (11,0) |
| DSPCPH | Controller cache partial read hits: The number of times that a portion of the data requested by the read operation was obtained from the controller read and write cache. An operation to the device was required to obtain the remaining data. | PD (11,0) |
| DSCCWH | Controller cache writes hits: The number of times that the data associated with the write operation replaces or is combined with existing data in the controller write cache. This eliminates a write operation. | PD (11,0) |
| DSCCFW | Controller cache fast writes: The number of times that space was available in the controller write cache for all of the data associated with a write operation and a response was returned immediately. | PD (11,0) |
| DSCOMP | Compressed Unit indicator. '0' if disk data is not compressed and '1' if disk data is compressed. | C (1) |
| DSPBU | Physical blocks used. For compressed units, this field contains the total number of physical blocks used (written) in the device user data area. For non-compressed units, this field contains 0. | PD (11,0) |
| DSPBA | Physical blocks allocated. For compressed units, this field contains the total number of physical blocks committed (reserved) in the device user data area for DASD extents. This value includes all of the Physical Blocks Used. For non-compressed units, this field contains 0. | PD (11,0) |
| DSLBW | Logical blocks written. For compressed units, this field contains the total number of logical blocks written in the device user data area. This value represents the total amount of data written to allocated extents. For non-compressed units, this field contains 0. | PD (11,0) |
| DSLBA | Logical blocks allocated. For compressed units, this field contains the total number of logical blocks contained in allocated compression groups. This value represents the total sum of all allocated compression groups in the device user data area. For non-compressed units, this field contains 0. | PD (11,0) |
| DSPBCO | Physical blocks for compression overhead. For compressed units, this field contains the total number of physical blocks that are used for compression directory structures and reserved areas that are unavailable for storing user data. For non-compressed units, this field contains 0. | PD (11,0) |
| DSFGDR | Foreground directory reads. For compressed units, this field is the number of device read operations that have been performed to read directory structures required to complete host system commands. For non-compressed units, this field contains 0. | PD (11,0) |
| DSFGDW | Foreground directory writes. For compressed units this is the number of device write operations that have been performed to write directory structures required to complete host system commands. For non-compressed units, this field contains 0. | PD (11,0) |
| DSBGDR | Background directory reads. For compressed units, this is the number of device read operations that have been performed in the management of compression directory structures, but were not immediately required to complete host system commands. For non-compressed units, this field contains 0. | PD (11,0) |
| DSBGDW | Background directory writes. For compressed units, this is the number of device write operations. For non-compressed units, this field contains 0. | PD (11,0) |
| DSFGRE | Foreground read exceptions. For compressed units, this is the number of times an additional device read operation was issued to read data that had been stored in the exception area on a compressed device (this count applies only to multi-page operations). This count reflects only those operations immediately required to complete host system commands. | PD (11,0) |
| DSFGWE | Foreground write exceptions. For compressed units, this field is the number of times an additional device write operation was issued to write data into the exception area on a compressed device (this count applies only to multi-page operations). This count reflects only those operations immediately required to complete host system commands. For non-compressed units, this field contains 0. | PD (11,0) |
| DSFGS | Foreground sweeps. For compressed units, a sweep is the process used to store a 1-MB compression group in the correct number of sectors so there are no unused areas in the data region and no used areas in the exception region of the compression group. The number of foreground sweeps is the number of times an entire 1-MB compression group was required to be swept to complete host system commands. The sweep is needed because the data for a host system write operation does not fit into the physical space reserved. The new data does not compress as well as the data that was previously in the space. For non-compressed units, this field contains 0. | PD (11,0) |
| DSBGS | Background sweeps. For compressed units, a sweep is the process used to store a 1-MB compression group in the correct number of sectors so there are no unused areas in the data region and no used areas in the exception region of the compression group. The number of background sweeps is the number of times an entire 1-MB compression group was swept to maintain the compressed data storage efficiency. This count reflects only those sweeps that were not immediately required to complete host system commands. Background sweeps are intended to increase performance or increase usable capacity of drive. For non-compressed units, this field contains 0. | PD (11,0) |
| DSCERC | Controller simulated read cache hits: The number of times that all of the data requested by the read operation could have been, but was not, obtained from a controller read cache (not the controller write cache). This field is updated only when Extended Adaptive Cache Simulator is enabled. | PD (11,0) |
| DSASPN | Auxiliary storage pool resource name. Specifies the resource name of the auxiliary storage pool to which this unit is currently allocated. A value of blanks specifies the system auxiliary storage pool or a basic auxiliary storage pool. | C (10) |
| DSPS | Parity set. The valid value for this field is '1' or '0'. The value of this field is '1' when the disk unit is in a parity set; otherwise, it is '0'. | C (1) |
| DSHAPS | High availability parity set. The valid value for this field is '1' or '0'. The value of this field is '1' when the disk unit is in a high availability parity set; otherwise, it is '0'. | C (1) |
| DSMU | Multipath unit. The valid value for this field is '1' or '0'. The value of this field is '1' when the disk resource represents a multipath disk unit (see note 5); otherwise, it is '0'. | C (1) |
| DSIP | Initial path of multipath unit. The valid value for this field is '1' or '0'. The value of this field is '1' when the disk resource represents the initial path of a multipath disk unit; otherwise it is '0'. The initial path is the first path observed by the system. It can change after restarting the system (IPL). The resource name of the initial path can be used for reporting a multipath disk unit under a single resource name. | C (1) |
| DSPC | Production copy of remotely mirrored independent auxiliary storage pool. The valid value for this field is '1' or '0'. The value of this field is '1' when the disk unit is in a production copy of a remotely mirrored independent auxiliary storage pool; otherwise, it is '0'. | C (1) |
| DSMC | Mirror copy of remotely mirrored independent auxiliary storage pool. The valid value for this field is '1' or '0'. The value of this field is '1' when the disk unit is in a mirror copy of a remotely mirrored independent auxiliary storage pool; otherwise, it is '0'. | C (1) |
| DSRDT | RAID type: type of RAID parity set for this disk unit. The valid value for this field is '1' or '0'. This field only has meaning for disk units in a parity set (DSPS field set to '1'). '0' = RAID 5 parity set, '1' = RAID 6 parity set. | C (1) |
| DSIOPF | Managed by IOP. The valid value for this field is '1' or '0'. The value of this field is '1' when this disk unit is attached to the disk storage adapter which is managed by IOP; otherwise, it is '0'. When data is collected by operating system versions earlier than V5R4, this field is always set to '1', because earlier versions cannot determine if the disk unit was IOP-based or not. | C (1) |
| DSCAT | Disk unit category. This field indicates if this disk unit has some special characteristics, which may require a special interpretation of its performance data. This can also be determined by examining device type and model for this disk unit. X’00’ = no special category applies, X’01’ = this disk unit is located in external storage media. | C (1) |
| DSSRVT | The following information applies if you have installed the latest PTFs.
Disk service time (see note 6). Combined service time of all disk operations completed since last sample (milliseconds). Divide by number of read and write commands to obtain average service time. Set to zero if data is not available. | B(9,0) |
| DSWT | The following information applies if you have installed the latest PTFs.
Disk wait time. Combined wait (queue) time of all disk operations completed since last sample (milliseconds). Divide by number of read and write commands to obtain average wait (queue) time. Add to disk service time to obtain disk response time. Set to zero if data is not available. | B(9,0) |
| DSBKCT1 | The following information applies if you have installed the latest PTFs.
Disk operations in disk response time bucket 1 (see note 7). Number of disk operations since last sample, the response time of which was less than the first disk response time boundary. The disk response time boundaries are reported in the QAPMCONF file. | B(9,0) |
| DSBKRT1 | The following information applies if you have installed the latest PTFs.
Disk response time in disk response time bucket 1. Combined response time of all disk operations since last sample, the response time of which was less than the first disk response time boundary (milliseconds). | B(9,0) |
| DSBKST1 | The following information applies if you have installed the latest PTFs.
Disk service time in disk response time bucket 1. Combined service time of all disk operations since last sample, the response time of which was less than the first disk response time boundary (milliseconds). | B(9,0) |
| DSBKCT2 | The following information applies if you have installed the latest PTFs.
Disk operations in disk response time bucket 2 (see note 7). Number of disk operations since last sample, the response time of which was greater than the first disk response time boundary but less than the second disk response time boundary. The disk response time boundaries are reported in the QAPMCONF file. | B(9,0) |
| DSBKRT2 | The following information applies if you have installed the latest PTFs.
Disk response time in disk response time bucket 2. Combined response time of all disk operations since last sample, the response time of which was greater than the first disk response time boundary but less than the second disk response time boundary (milliseconds). | B(9,0) |
| DSBKST2 | The following information applies if you have installed the latest PTFs.
Disk service time in disk response time bucket 2. Combined service time of all disk operations since last sample, the response time of which was greater than the first disk response time boundary but less than the second disk response time boundary (milliseconds). | B(9,0) |
| DSBKCT3 | The following information applies if you have installed the latest PTFs.
Disk operations in disk response time bucket 3 (see note 7). Number of disk operations since last sample, the response time of which was greater than the second disk response time boundary but less than the third disk response time boundary. The disk response time boundaries are reported in the QAPMCONF file. | B(9,0) |
| DSBKRT3 | The following information applies if you have installed the latest PTFs.
Disk response time in disk response time bucket 3. Combined response time of all disk operations since last sample, the response time of which was greater than the second disk response time boundary but less than the third disk response time boundary (milliseconds). | B(9,0) |
| DSBKST3 | The following information applies if you have installed the latest PTFs.
Disk service time in disk response time bucket 3. Combined service time of all disk operations since last sample, the response time of which was greater than the second disk response time boundary but less than the third disk response time boundary (milliseconds). | B(9,0) |
| DSBKCT4 | The following information applies if you have installed the latest PTFs.
Disk operations in disk response time bucket 4 (see note 7). Number of disk operations since last sample, the response time of which was greater than the third disk response time boundary but less than the fourth disk response time boundary. The disk response time boundaries are reported in the QAPMCONF file. | B(9,0) |
| DSBKRT4 | The following information applies if you have installed the latest PTFs.
Disk response time in disk response time bucket 4. Combined response time of all disk operations since last sample, the response time of which was greater than the third disk response time boundary but less than the fourth disk response time boundary (milliseconds). | B(9,0) |
| DSBKST4 | The following information applies if you have installed the latest PTFs.
Disk service time in disk response time bucket 4. Combined service time of all disk operations since last sample, the response time of which was greater than the third disk response time boundary but less than the fourth disk response time boundary (milliseconds). | B(9,0) |
| DSBKCT5 | The following information applies if you have installed the latest PTFs.
Disk operations in disk response time bucket 5 (see note 7). Number of disk operations since last sample, the response time of which was greater than the fourth disk response time boundary but less than the fifth disk response time boundary. The disk response time boundaries are reported in the QAPMCONF file. | B(9,0) |
| DSBKRT5 | The following information applies if you have installed the latest PTFs.
Disk response time in disk response time bucket 5. Combined response time of all disk operations since last sample, the response time of which was greater than the fourth disk response time boundary but less than the fifth disk response time boundary (milliseconds). | B(9,0) |
| DSBKST5 | The following information applies if you have installed the latest PTFs.
Disk service time in disk response time bucket 5. Combined service time of all disk operations since last sample, the response time of which was greater than the fourth disk response time boundary but less than the fifth disk response time boundary (milliseconds). | B(9,0) |
| DSBKCT6 | The following information applies if you have installed the latest PTFs.
Disk operations in disk response time bucket 6 (see note 7). Number of disk operations since last sample, the response time of which was greater than the fifth disk response time boundary. The disk response time boundaries are reported in the QAPMCONF file. | B(9,0) |
| DSBKRT6 | The following information applies if you have installed the latest PTFs.
Disk response time in disk response time bucket 6. Combined response time of all disk operations since last sample, the response time of which was greater than the fifth disk response time boundary (milliseconds). | B(9,0) |
| DSBKST6 | The following information applies if you have installed the latest PTFs.
Disk service time in disk response time bucket 6. Combined service time of all disk operations since last sample, the response time of which was greater than the fifth disk response time boundary (milliseconds). | B(9,0) |
9335: > 2/3 9332: >= 2/3
> 1/3 and <= 2/3 >= 1/3 and <2/3
> 1/6 and <= 1/3 >= 1/6 and <1/3
> 1/12 and <= 1/6 >= 1/12 and <1/6
<= 1/12 < 1/12
Convert the product of the idle loop count times the idle loop time from hundredths of microseconds to seconds. Subtract this from the interval time, and divide the result by the interval time. For example:
Disk processor utilization = (INTSEC - (DSIDLC * DSIDLT)/10**8)/ INTSEC
DSUTL = Arm Busy = (DSSMPL - DSNBSY)/DSSMPL
DSAS = (DSRDS + DSWRTS)/INTSEC
DSSRVCT = DSUTL/DSAS
Use the following formula to calculate the service time (DSSTM) for a multipath disk unit, where Xi is the calculated value of X for the i-th path and sum(Xi) is the sum of Xi over all paths:
DSSTM = sum(DSSRVCTi * (DSRDSi + DSWRTSi)) / sum(DSRDSi + DSWRTSi)
If the disk unit is managed by an IOP (DSIOPF = ‘1’) and if the operation rate is very low, the service time calculated with this formula should be ignored. This is a calculated value based on data obtained through sampling. When the number of operations is small compared to the number of samples, the statistical error makes the result unreliable.
The formulas shown above for disk utilization and disk service time are based on a simplified statistical model. The results produced by these formulas should only be used as an estimate.
Other field values that are duplicated include drive capacity (DSCAP), and drive available space (DSAVL), .
The arm number (DSARM) and mirror flag (DMFLAG) of a particular multipath disk unit can be used to identify the records associated with that unit.