# Application Volume Performance

The Application Volume Performance attributes provide performance information for the logical volumes allocated to an application.

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 ratio, expressed as a percentage, of the total busy time this interval divided by the interval length.

Bypass Cache Percent: The percentage of I/O that goes directly to a DASD device regardless of whether the data might be or currently is cached.

Cache Status: Indicates whether caching is enabled for this device. Values are Timeout, Active, Inactive, Pending Active, Pending Inactive, and n/a.

Cache to DASD Total Tracks: The number of tracks written from cache to physical disk during the cache interval. This value is captured asynchronously with respect to the transfer of data from the channel to the cache.

Cache to DASD Tracks per Sec: The rate per second of tracks written from cache to physical disk during the cache interval. This value is captured asynchronously with respect to the transfer of data from the channel to the cache.

CFW Read Percent: The percentage of I/O requests read from cache that were in cache due to a cache fast write.

CFW Write Percent: The percentage of I/Os that were cache fast write requests. Cache Fast Write (CFW) is a function of 3990 controllers that writes data to cache at channel speed. The data is later written to DASD. Cache fast write differs from DASD fast write in that the data is not written to NVS (nonvolatile storage).

Connect Time: The part of I/O during which data is located on the track and transferred between the DASD device and central storage.

Current PAV Exposures: The number of exposures for the device when the data was gathered.

DASD to Cache Non Promotes Second: The rate per second of operations that did not promote (copy) a track to cache because free cache segments were not available. Non promotes are tracks that the system does not copy to cache because free cache segments were not available.

DASD to Cache Non Promotes: The number of operations that did not promote (copy) a track to cache because free cache segments were not available. Non promotes are tracks that the system does not copy to cache because free cache segments were not available.

DASD to Cache Total Tracks Non-sequential: The number of tracks read from physical disk to cache over the cache interval for non-sequential I/O operations.

DASD to Cache Total Tracks Sequential: The number of tracks read from physical disk to cache over the cache interval for sequential I/O operations.

DASD to Cache Total Tracks: The number of tracks read from physical disk to cache over the cache interval for I/O operations.

DASD to Cache Tracks per Sec Non-sequential: The rate per second of tracks read from physical disk to cache over the cache interval for non-sequential I/O operations.

DASD to Cache Tracks per Sec Sequential: The rate per second of tracks read from physical disk to cache over the cache interval for sequential I/O operations.

DASD to Cache Tracks per Sec: The rate per second of tracks read from physical disk to cache over the cache interval for I/O operations.

DCBs Open: The count of open DCBs for data sets.

Device Address: The MVS™ device number, assigned by HCD, associated with this device.

Device MPL: The device Multi-Processing Level, which is the I/O density for a device. This metric is the product of the MSR (millisecond response time) and I/O per second for a device.

DFW Hit Percent: The ratio of I/O requests where data is written to both cache and nonvolatile storage that was satisfied by the storage control cache without requiring access to the hard disk.

DFW Retry Percent: The percentage of DASD fast write operations that did not complete due to NVS (nonvolatile storage) constraint.

DFW Status: Indicates whether DASD Fast Write is enabled on this device.

Disconnect Time: Time that I/O spends, freed from the channel, searching for or requesting data. This time includes moving the device to the requested cylinder and track, waiting for the record to rotate under the head (rotational delay), and waiting for the channel to become available.

I/O Count: The total number if I/O operations performed on this device during this interval.

I/O Per Second: The average number of input/output operations, per second, directed at this volume during this interval.

Inhibit Cache Percent: The percentage of I/O that used the MVS I/O mechanism to prevent a request from being cached, even if it is eligible. If the data is already in cache, the request is satisfied by cache.

IOSQ Delay: The average time that an I/O waits because the device is already busy (signified by the UCBBUSY bit for the device being on).

Job Name: The MVS JOBNAME, TSO user ID, or started task name associated with this application.

Managed System: The SMS name of this system.

Maximum PAV Exposures: The maximum number of exposures for a device over the current RMF interval.

MSR Connect Time Percent: The ratio of average connect time divided by average total response time.

PAV Exposure Changed: An indicator that the number of PAV exposures for the volume has changed over the interval.

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

Physical Device: The physical device type.

Read Hit Percent: The ratio of read requests that were satisfied by the storage control unit cache without requiring access to DASD.

Read I/O Count: The number of read requests in the current collection interval.

Read I/O Percent: The percentage of I/O requests that were read requests.

Reserved Percent: The percentage of time during the interval when a shared device was 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.

Storage Group Name: Indicates whether the number of PAV exposures for this device has changed during this interval.

Subsystem ID: The subsystem ID.

Time Stamp: The date and time this data was reported.

Volume: Represents the six-character identifier associated with this logical volume.

Write Hit Percent: The ratio of write hit requests that were satisfied by the storage control unit cache without requiring access to DASD.

Write I/O Count: The number of write requests in the current collection interval.