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<h1 class="topictitle1">Performance data files: QAPMDISK</h1>
<div><p>This database file includes disk file entries and contains one
record for each disk resource.</p>
<div class="section"><p>Typically, there is one disk resource per disk unit except for
a multipath disk unit that has multiple disk resources associated with it. </p>
<div class="tablenoborder"><!-- Link to dynamic table -->
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<!-- End of link to dynamic table --><table cellpadding="4" cellspacing="0" summary="" frame="border" border="1" rules="all"><thead align="left"><tr><th valign="top" id="d0e22">Field Name</th>
<th valign="top" id="d0e24">Description</th>
<th valign="top" id="d0e26">Attribute</th>
</tr>
</thead>
<tbody><tr><td valign="top" headers="d0e22 ">INTNUM</td>
<td valign="top" headers="d0e24 ">Interval number: The <em>n</em>th sample database interval based on the
start time specified in the Create Performance Data (CRTPFRDTA) command.</td>
<td valign="top" headers="d0e26 ">PD (5,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DTETIM</td>
<td valign="top" headers="d0e24 ">Interval date (<var class="varname">yymmdd</var>) and time (<var class="varname">hhmmss</var>):
The date and time of the sample interval.</td>
<td valign="top" headers="d0e26 ">C (12)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">INTSEC</td>
<td valign="top" headers="d0e24 ">Elapsed interval seconds: The number of seconds since the last sample
interval.</td>
<td valign="top" headers="d0e26 ">PD (7,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">IOPRN</td>
<td valign="top" headers="d0e24 ">IOP resource name</td>
<td valign="top" headers="d0e26 ">C (10)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DIOPID</td>
<td valign="top" headers="d0e24 ">Reserved</td>
<td valign="top" headers="d0e26 ">C (1)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSARM</td>
<td valign="top" headers="d0e24 ">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 ASP.</td>
<td valign="top" headers="d0e26 ">C (4)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSTYPE</td>
<td valign="top" headers="d0e24 ">Disk drive type such as 9332, 9335, or 6100.</td>
<td valign="top" headers="d0e26 ">C (4)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSDRN</td>
<td valign="top" headers="d0e24 ">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 <a href="#rzahxqapmdisk__qapmdisknote5">5</a>).</td>
<td valign="top" headers="d0e26 ">C (10)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSSCAN</td>
<td valign="top" headers="d0e24 ">Number of search string commands: This count is always zero, because
search string commands are not supported for the 9332, 9335, or 6100.</td>
<td valign="top" headers="d0e26 ">PD (5,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSBLKR </td>
<td valign="top" headers="d0e24 "><span><img src="./delta.gif" alt="Start of change" />Number of blocks read: Block is one sector
on the disk drive.<img src="./deltaend.gif" alt="End of change" /></span></td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSBLKW </td>
<td valign="top" headers="d0e24 "><span><img src="./delta.gif" alt="Start of change" />Number of blocks written: Block is one
sector on the disk drive.<img src="./deltaend.gif" alt="End of change" /></span> </td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSBLKR</td>
<td valign="top" headers="d0e24 ">Number of blocks read: The block length is 520 bytes, which includes
8 bytes of system control information.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSBLKW</td>
<td valign="top" headers="d0e24 ">Number of blocks written: The block length is 520 bytes, which includes
8 bytes of system control information.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSIDLC</td>
<td valign="top" headers="d0e24 ">Processor idle loop counter (see note <a href="#rzahxqapmdisk__qapmdisknote1">1</a>):
The number of times the disk controller passed through the idle loop. This
count is increased differently for the 9332 and the 9335. For the 9332, this
counter is increased only if the disk controller is totally idle (for example,
no I/O operations are active.) For the 9335, even though the disk controller
may be idle and the counter gets increased, an I/O operation can be active
(for example, seek is being performed.) This field is nonzero for drive types
that support a dedicated disk processor and zero for other drive types. <p>DSIDLC
and DSIDLT are duplicated across all arms for the same disk controller.</p>
</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSIDLT</td>
<td valign="top" headers="d0e24 ">Processor idle loop time (see note <a href="#rzahxqapmdisk__qapmdisknote3">3</a>):
The time (in hundredths of microseconds) to make one pass through the idle
loop. This field is nonzero for drive types that support a dedicated disk
processor and zero for other drive types. 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. <p>DSIDLC and DSIDLT are duplicated across
all arms for the same disk controller.</p>
</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSSK1</td>
<td valign="top" headers="d0e24 ">Number of seeks &gt; 2/3: The number of times the arm traveled more
than 2/3 of the disk on a seek.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSSK2</td>
<td valign="top" headers="d0e24 ">Number of seeks &gt; 1/3 and &lt; 2/3 (see note <a href="#rzahxqapmdisk__qampmdisknote2">2</a>):
The number of times the arm traveled more than 1/3 but less than 2/3 of the
disk on a seek.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSSK3</td>
<td valign="top" headers="d0e24 ">Number of seeks &gt; 1/6 and &lt; 1/3 (see note <a href="#rzahxqapmdisk__qampmdisknote2">2</a>):
The number of times the arm traveled more than 1/6 but less than 1/3 of the
disk on a seek.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSSK4</td>
<td valign="top" headers="d0e24 ">Number of seeks &gt; 1/12 and &lt; 1/6 (see note <a href="#rzahxqapmdisk__qampmdisknote2">2</a>):
The number of times the arm traveled more than 1/12 but less than 1/6 of the
disk on a seek.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSSK5</td>
<td valign="top" headers="d0e24 ">Number of seeks &lt; 1/12 (see note <a href="#rzahxqapmdisk__qampmdisknote2">2</a>):
The number of times the arm traveled from its current position but less than
1/12 of the disk on a seek.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSSK6</td>
<td valign="top" headers="d0e24 ">Number of zero seeks (see note <a href="#rzahxqapmdisk__qampmdisknote2">2</a>):
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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSQUEL</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSNBSY</td>
<td valign="top" headers="d0e24 ">Number of times arm not busy: The number of times there were no outstanding
I/O operations active at sample time.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSSMPL </td>
<td valign="top" headers="d0e24 "><span><img src="./delta.gif" alt="Start of change" />Number of samples taken: The number of
samples taken for the DSQUEL and DSNBSY fields.<img src="./deltaend.gif" alt="End of change" /></span> </td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSCAP</td>
<td valign="top" headers="d0e24 ">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 ASP containing it is not under checksum protection. The unit reserved
system space value is subtracted from the unit capacity to calculate this
capacity.</td>
<td valign="top" headers="d0e26 ">PD (15,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSAVL</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (15,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSASP</td>
<td valign="top" headers="d0e24 ">ASP number: Specifies the ASP to which this unit is currently allocated.
A value of 1 specifies the system ASP. A value from 2 through 32 specifies
a basic ASP. A value from 33 to 255 specifies an independent ASP. A value
of 0 indicates that this unit is currently not allocated.</td>
<td valign="top" headers="d0e26 ">PD (5,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSCSS</td>
<td valign="top" headers="d0e24 ">Reserved</td>
<td valign="top" headers="d0e26 ">C (2)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSPCAP</td>
<td valign="top" headers="d0e24 ">Reserved</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSPAVL</td>
<td valign="top" headers="d0e24 ">Reserved</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DMFLAG</td>
<td valign="top" headers="d0e24 ">' ' 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.</td>
<td valign="top" headers="d0e26 ">C (1)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DMSTS</td>
<td valign="top" headers="d0e24 ">Local mirroring status. 1 = active, 2 = resuming, 3 = suspended</td>
<td valign="top" headers="d0e26 ">PD (1,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DMIRN</td>
<td valign="top" headers="d0e24 ">Locally mirrored IOP resource name</td>
<td valign="top" headers="d0e26 ">C (10)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DMDRN</td>
<td valign="top" headers="d0e24 ">Locally mirrored device resource name</td>
<td valign="top" headers="d0e26 ">C (10)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSRDS</td>
<td valign="top" headers="d0e24 ">Number of read data commands.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSWRTS</td>
<td valign="top" headers="d0e24 ">Number of write data commands.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSBUFO</td>
<td valign="top" headers="d0e24 ">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. This field is 0 for disk drive type
6100.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSBUFU</td>
<td valign="top" headers="d0e24 ">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. This field is 0 for disk drive type 6100.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSMDLN</td>
<td valign="top" headers="d0e24 ">Model Number: The model number of the disk drive.</td>
<td valign="top" headers="d0e26 ">C (4)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSDCRH</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSDCPH</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSDCWH</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSDCFW</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSDROP</td>
<td valign="top" headers="d0e24 ">Device read operations: The number of read operations issued to the
device by the controller. This includes operations generated for redundant
system data areas. It does not include operations generated for diagnostics
or access to the controller reserved area that occur during this idle time.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSDWOP</td>
<td valign="top" headers="d0e24 ">Device write operations: The number of write operations issued to the
device by the controller. This includes operations generated for redundant
system data areas. It does not include operations generated for diagnostics
or access to the controller reserved area that occur during this idle time.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSCCRH</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSPCPH</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSCCWH</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSCCFW</td>
<td valign="top" headers="d0e24 ">Controller cache fast writes: The number of times that space was available
in the controller write cache for the data associated with a write operation
and a response was returned immediately.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSCOMP</td>
<td valign="top" headers="d0e24 ">Compressed Unit indicator. '0' if disk data is not compressed and '1'
if disk data is compressed.</td>
<td valign="top" headers="d0e26 ">C (1)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSPBU</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSPBA</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSLBW</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSLBA</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSPBCO</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSFGDR</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSFGDW</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSBGDR</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSBGDW</td>
<td valign="top" headers="d0e24 ">Background directory writes. For compressed units, this is the number
of device write operations. For non-compressed units, this field contains
0.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSFGRE</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSFGWE</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSFGS</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSBGS</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSCERC</td>
<td valign="top" headers="d0e24 ">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.</td>
<td valign="top" headers="d0e26 ">PD (11,0)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSASPN</td>
<td valign="top" headers="d0e24 ">ASP resource name. Specifies the resource name of the ASP to which
this unit is currently allocated. A value of blanks specifies the system ASP
or a basic ASP.</td>
<td valign="top" headers="d0e26 ">C (10)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSPS</td>
<td valign="top" headers="d0e24 ">Parity set. <span><img src="./delta.gif" alt="Start of change" />The valid value for this field is '1' or
'0'.<img src="./deltaend.gif" alt="End of change" /></span> The value of this field is '1' when the disk unit is in a parity
set; otherwise, it is '0'.</td>
<td valign="top" headers="d0e26 ">C (1)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSHAPS</td>
<td valign="top" headers="d0e24 ">High availability parity set. <span><img src="./delta.gif" alt="Start of change" />The valid value for this
field is '1' or '0'.<img src="./deltaend.gif" alt="End of change" /></span> The value of this field is '1' when the disk unit
is in a high availability parity set; otherwise, it is '0'.</td>
<td valign="top" headers="d0e26 ">C (1)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSMU</td>
<td valign="top" headers="d0e24 ">Multipath unit. <span><img src="./delta.gif" alt="Start of change" />The valid value for this field is '1'
or '0'.<img src="./deltaend.gif" alt="End of change" /></span> The value of this field is '1' when the disk resource represents
a multipath disk unit (see note <a href="#rzahxqapmdisk__qapmdisknote5">5</a>);
otherwise, it is '0'.</td>
<td valign="top" headers="d0e26 ">C (1)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSIP</td>
<td valign="top" headers="d0e24 ">Initial path of multipath unit. <span><img src="./delta.gif" alt="Start of change" />The valid value for
this field is '1' or '0'.<img src="./deltaend.gif" alt="End of change" /></span> 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.</td>
<td valign="top" headers="d0e26 ">C (1)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSPC</td>
<td valign="top" headers="d0e24 ">Production copy of remotely mirrored independent ASP. <span><img src="./delta.gif" alt="Start of change" />The
valid value for this field is '1' or '0'.<img src="./deltaend.gif" alt="End of change" /></span> The value of this field is
'1' when the disk unit is in a production copy of a remotely mirrored independent
ASP; otherwise, it is '0'.</td>
<td valign="top" headers="d0e26 ">C (1)</td>
</tr>
<tr><td valign="top" headers="d0e22 ">DSMC</td>
<td valign="top" headers="d0e24 ">Mirror copy of remotely mirrored independent ASP. <span><img src="./delta.gif" alt="Start of change" />The
valid value for this field is '1' or '0'.<img src="./deltaend.gif" alt="End of change" /></span> The value of this field is
'1' when the disk unit is in a mirror copy of a remotely mirrored independent
ASP; otherwise, it is '0'.</td>
<td valign="top" headers="d0e26 ">C (1)</td>
</tr>
<tr><td valign="top" headers="d0e22 "><span><img src="./delta.gif" alt="Start of change" />DSRDT<img src="./deltaend.gif" alt="End of change" /></span> </td>
<td valign="top" headers="d0e24 "><span><img src="./delta.gif" alt="Start of change" />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.<img src="./deltaend.gif" alt="End of change" /></span></td>
<td valign="top" headers="d0e26 "><span><img src="./delta.gif" alt="Start of change" />C (1) <img src="./deltaend.gif" alt="End of change" /></span></td>
</tr>
<tr><td valign="top" headers="d0e22 "><span><img src="./delta.gif" alt="Start of change" />DSIOPF<img src="./deltaend.gif" alt="End of change" /></span> </td>
<td valign="top" headers="d0e24 "><span><img src="./delta.gif" alt="Start of change" />Managed by IOP (See note <a href="#rzahxqapmdisk__qapmdisknote6">6</a>).
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'.<img src="./deltaend.gif" alt="End of change" /></span></td>
<td valign="top" headers="d0e26 "><span><img src="./delta.gif" alt="Start of change" />C (1) <img src="./deltaend.gif" alt="End of change" /></span></td>
</tr>
<tr><td valign="top" headers="d0e22 "><span><img src="./delta.gif" alt="Start of change" />DSCAT<img src="./deltaend.gif" alt="End of change" /></span> </td>
<td valign="top" headers="d0e24 "><span><img src="./delta.gif" alt="Start of change" />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.<img src="./deltaend.gif" alt="End of change" /></span> </td>
<td valign="top" headers="d0e26 "><span><img src="./delta.gif" alt="Start of change" />C (1) <img src="./deltaend.gif" alt="End of change" /></span></td>
</tr>
</tbody>
</table>
</div>
<div class="note"><span class="notetitle">Notes:</span> <ol><li id="rzahxqapmdisk__qapmdisknote1"><a name="rzahxqapmdisk__qapmdisknote1"><!-- --></a> 9332/9335 inconsistencies: <ul><li>9335 updates the idle count only when the processing unit (A) is not busy.
Disk operations such as seek could be in progress. 9332 updates the idle count
when there is no activity in any of its processors.</li>
<li>If there is no movement and no head switch, the 9332 does not count this
operation as a zero seek; the 9335 does.</li>
<li>If an operation causes a head switch (starts a read or write on one track
and ends up on another track), the 9332 counts this as a zero seek; the 9335
does not.</li>
</ul>
</li>
<li id="rzahxqapmdisk__qampmdisknote2"><a name="rzahxqapmdisk__qampmdisknote2"><!-- --></a> <pre>9335: &gt; 2/3 9332: &gt;= 2/3
&gt; 1/3 and &lt;= 2/3 &gt;= 1/3 and &lt;2/3
&gt; 1/6 and &lt;= 1/3 &gt;= 1/6 and &lt;1/3
&gt; 1/12 and &lt;= 1/6 &gt;= 1/12 and &lt;1/6
&lt;= 1/12 &lt; 1/12
</pre>
</li>
<li id="rzahxqapmdisk__qapmdisknote3"><a name="rzahxqapmdisk__qapmdisknote3"><!-- --></a>The idle loop count and time are used to calculate
the storage device controller utilization as follows: <p>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:</p>
<p>Disk processor utilization = (INTSEC
- (DSIDLC * DSIDLT)/10**8)/ INTSEC</p>
</li>
<li id="rzahxqapmdisk__qapmdisknote4"><a name="rzahxqapmdisk__qapmdisknote4"><!-- --></a>The following formulas describe how several of the
fields in the previous table can be used to calculate utilization and service
time for each arm. For a multipath disk unit, these formulas will give the
utilization and service time for each path (resource). <ul><li>Arm utilization (DSUTL): The part of the total interval that the arm was
being used for I/O operations. <pre>DSUTL = Arm Busy = (DSSMPL - DSNBSY)/DSSMPL</pre>
</li>
<li>Arm accesses per second (DSAS): The number of reads and writes per second
for this arm during the interval. <pre>DSAS = (DSRDS + DSWRTS)/INTSEC</pre>
</li>
<li>Service time (DSSRVCT): The average time for an arm I/O operation. This
includes disk controller time. <pre>DSSRVCT = DSUTL/DSAS</pre>
<p>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:</p>
<pre>DSSTM = sum(DSSRVCTi * (DSRDSi + DSWRTSi)) / sum(DSRDSi + DSWRTSi)</pre>
<p>At
low disk utilizations (less than 5%), the service time should be ignored,
if this disk unit is managed by IOP (value of DSIOPF field is 1). This is
a calculated value based on statistical sampling. When the number of samples
is very low, the calculated value may not be accurate.</p>
</li>
</ul>
</li>
<li id="rzahxqapmdisk__qapmdisknote5"><a name="rzahxqapmdisk__qapmdisknote5"><!-- --></a>Performance data is reported for each disk resource
that is associated with a multipath disk unit. For a multipath disk unit,
the following counters come from the device, which means that their values
are duplicated for each disk resource that is reported: <ul><li>DSIDLC - Processor idle loop count</li>
<li>DSIDLT - Processor idle loop time</li>
<li>DSSK1-6 - Number of seeks</li>
<li>DSBUFO - Number of buffer overruns</li>
<li>DSBUFU - Number of buffer underruns</li>
<li>DSDCRH - Device cache read hits</li>
<li>DSDCPH - Device cache partial read hits</li>
<li>DSDCWH - Device cache write hits</li>
<li>DSDCFW - Device cache fast writers</li>
<li>DSDROP - Device read operations</li>
<li>DSDWOP - Device write operations</li>
</ul>
<p>Other field values that are duplicated include drive capacity (DSCAP)
and drive available space (DSAVL).</p>
<p>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.</p>
</li>
<li id="rzahxqapmdisk__qapmdisknote6"><a name="rzahxqapmdisk__qapmdisknote6"><!-- --></a><img src="./delta.gif" alt="Start of change" />When data is collected on operating system
versions earlier than V5R4, this field is always set to 1, because previous
versions cannot determine if the disk unit was IOP-based or not.<img src="./deltaend.gif" alt="End of change" /></li>
</ol>
</div>
</div>
</div>
<div>
<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="rzahxapsparent.htm" title="Managing performance on iSeries systems requires the use of a variety of specialized applications. Each of these applications offers a specific insight into system performance. This topic explains several applications and the intended use of each application.">Applications for performance management</a></div>
</div>
</div>
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