# DASD Volume Performance

The DASD Volume Performance attributes provide status and performance information for logical volumes.

Average Command Response Delay: The average number of milliseconds that a successfully initiated start or resume function needs until the first command is indicated as accepted by the device over the RMF™ interval.

Average HyperPAV Alias Count: The average number of aliased devices assigned to a base volume in a HyperPAV environment over the RMF interval.

Busy Percent: The percentage of time a resource is busy processing I/O requests. For Parallel Access Volumes, this value is normalized by dividing by the number of PAV exposures.

Channels: The channel Path IDs (in hexadecimal) through which this device can be accessed.

CHPID SEL The CHPID selector is used as an index to limit the range of physical volumes for which data is requested.

Connect Time: The average time (in milliseconds) required for seek and transfer. This is the time it takes for data to be located on the track and transferred between the DASD device and central storage.

Control Unit Busy Delay Time: The average amount of I/O delay (in milliseconds) to this device caused by a control unit busy condition.

CU Model: The model indicator for this cache control unit.

Current PAV Exposures: The current number of UCBs through which the device can be accessed.

DCBs Open: The number of open data sets on this device.

Device Address: The MVS™ device number associated with this device.

Device Busy Delay Time: The average amount of I/O delay (in milliseconds) to this device caused by a device busy condition.

Device Hex Address: The device address in hexadecimal numbers.

Device Model: The MVS device model.

Device MPL: The device Multiprocessing Level, which is the I/O density for a device. This metric is the product of the MSR (millisecond response time) and I/O rate per second for the device. For a PAV volume, this value is normalized by dividing by the number of exposures.

Device Type: The MVS device type.

Director Busy Delay Time: The average amount of I/O delay (in milliseconds) to this device caused by a director port busy condition.

Disconnect Time: The average time in milliseconds that I/O waited because the device was not connected to the channel. This time includes moving the device to the requested cylinder, waiting for the record to rotate under the head (rotational delay), and waiting for the channel to become available.

I/O Count: The actual number of I/O requests issued to the device over the Resource Monitoring Facility (RMF) interval.

I/O Per Second: The average number of I/O operations per second.

IOSQ Delay: The average time (in milliseconds) that an I/O waits because the device is already busy. A device is determined to be busy if its UCBBUSY bit is on.

LCU Number Hex: The hexadecimal LCU number for this device.

LCU Number: The hexadecimal logical control unit number.

Managed System: The SMS name of this system.

Maximum PAV Exposures: The maximum number of UCBs through which the device can be accessed in this interval.

MSR Connect Time Percent: The percentage of the device response time during which the device was connected. This value is obtained be dividing the device pending time (in milliseconds) by the total millisecond response time.

MVS Status: The status of this device in the local MVS system. Values are Online, Offline, Pending Offline, Boxed, Not Ready, and Long Busy.

PAV Exposure Changed: Indicates whether the number of PAV exposures for the volume has changed over the interval.

Pend Time: The average time (in milliseconds) that I/O is delayed in the path to the device. Pending time can be attributable to the channel or control unit path being busy.

Physical Device: The type of physical device containing this logical device (supported for the following devices only: Shark 2105, Symmetrix, TDS). Values are 2105, Symmetrix, and TDS.

Raid Model: The raid type indicator. Values are Symmetrix, Iceberg, Ramac, or 2105.

Reserved Percent: The percentage of time during the interval when a shared device is reserved by this system.

Response Time: The total hardware service time and the front end software queuing time (in milliseconds) involved for the average I/O request to the device.

Solid State Device: Indicates whether the logical volume is backed by a solid state physical device.

SMFID: The SMF ID of the system from which this information was obtained.

SMS Conversion Status: The SMS conversion status of this volume. Values are Non-SMS, Initial, Converted, or Excluded.

SMS Status: The SMS volume status for a local system. Values are Not Connected, Enabled, Quiesced_All, Quiesced_New, Disabled_All, or Disabled_New.

Storage Group Name: The SMS storage group name to which this volume belongs.

Subsystem ID Index: The two-byte unique value used to identify a 3990 or equivalent storage control unit.

Time Stamp: The date and time associated with this row. Primarily for use in historical reporting.

User Group Index: The user-assigned name for a group of DASD volumes.

Volume: The volume serial number of a disk device currently in use by this application.

VTOC Index Status: The type of VTOC present on this device. Values are Enabled, Disabled, Error, OS VTOC, and Excluded.