# UDG Cache Devices

The UDG Cache Devices attributes provide information about the cache and the associated metrics for UDG devices.

Avg Logical KB Read: The average number of kilobytes read from the logical volume per second over the cache interval.

Avg Logical KB Written: The average number of kilobytes written to the logical volume per second over the cache interval.

Avg Logical Read Time: The average time spent reading from the logical volume per I/O over the cache interval.

Avg Logical Write Time: The average time spent writing to the logical volume per I/O over the cache interval.

Avg Phys Read Response Time: The average time to read from the physical disk per operation in milliseconds over the cache interval.

Avg Phys Write Response Time: The average time to write to the physical disk per operation over the cache interval.

Bypass Cache Percent: The percentage of I/O's that bypassed cache this interval. These I/O requests are sent directly to DASD. Tracks are neither read from cache nor promoted to cache and their entries in the LRU list are not updated.

Cache Status: The caching status for this subsystem. Active means caching is enabled for this subsystem. Inactive means caching is disabled for this subsystem.

Cache to DASD Tracks per Sec: The rate per second of tracks written from cache to physical disk over the cache interval asynchronous of the channel to cache transfer of data.

Cache to DASD Total Tracks: The number of tracks written from cache to physical disk over the cache interval asynchronous of the channel to cache transfer of data.

CFW Read Percent: The percentage of READ requests that were satisfied from cache due to a previous cache fast write.

CFW Write Percent: The percentage of I/O operations which were Cache Fast Write requests. Cache Fast Write allows data to be written to cache only. The data is later written to DASD. CFW differs from DASD Fast Write in that the data is not written to Non-Volatile Storage (NVS).

Channel Index: The channel path identifier defining the path on which this device resides.

Control Unit Model: The model number of the control unit to which this device is attached.

DASD to Cache Non Promotes: The number of operations that did not promote a track to cache because free cache segments were not available.

DASD to Cache Non Promotes per Second: The rate per second of operations that did not promote a track to cache because free cache segments were not available.

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.

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

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.

Device Address: Four hexadecimal digits that define the physical address of this device. Also known as unit or unit address.

Device Hex Address: The device address (in hexadecimal).

DFW Hit Percent: The percentage of DASD Fast Writes that were satisfied from cache without requiring access to DASD. DASD Fast Writes are written to both cache and Non-Volatile Storage (NVS).

DFW Retry Percent: The percentage of DASD Fast Write operations which could not complete due to Non-Volatile Storage (NVS) constraints.

DFW Status: Reports whether DASD Fast Write is enabled for this volume (the value can be Active, Inactive, Unknown, or Timeout).

Extent Pool ID: The extent pool identifier.

I/O Count: The number of I/O requests for this device in the current collection interval.

Inhibit Cache Percent: The percentage of I/O requests which set the "Inhibit Cache Load" mode in the channel program to prevent the data being cached. If the data is already in cache, the request is satisfied from cache.

Logical Control Unit Index: The system assigned subchannel address of the control unit to which this device is attached. An LCU is the logical representation of either a single control unit (with or without attached devices) or a group of control units that share devices.

Logical KB Read Total: The total number of kilobytes read from the logical volume over the cache interval.

Logical KB Written Total: The total number of kilobytes written to the logical volume over the cache interval.

Logical Read Time: The amount of time spent reading from the logical volume over the cache interval.

Logical Write Time: The amount of time spent writing to the logical volume over the cache interval.

Managed System: An internal node name used to identify the system from which this row of data was obtained.

Physical Device: Defines the type of cache controller on which this volume resides, such as 2105, TDS or Symmetrix.

Physical KB Read Rate: The kilobytes read from the physical disk per second over the cache interval.

Physical KB Read Total: The total kilobytes read from the physical disk over the cache interval.

Physical KB Write Rate: The kilobytes written to the physical disk per second over the cache interval.

Physical KB Write Total: The total kilobytes written to the physical disk over the cache interval.

Physical Read Rate: The rate of I\O read operations from the physical disk per second over the cache interval.

Physical Read Total: The total number of I\O read operations from the physical disk over the cache interval.

Physical Write Rate: The rate of I\O write operations to the physical disk per second over the cache interval.

Physical Write Total: The total number of I\O write operations to the physical disk over the cache interval.

Read Hit Percent: The percentage of READ requests which were satisfied from cache.

Read I/O Count: The number of READ requests for data on this device.

Read I/O Percent: The percentage of all I/O requests which were READ requests.

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

Storage Facility ID: The name of the storage group to which this volume belongs. The storage group is an SMS construct used to group DASD devices in order to separate the physical requirements of storing data from the logical requirements.

Storage Group Index: The storage facility identifier for the device (type-model-serial number).

SSID Index: The full word representation of the SSID used for indexing in the product.

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

Subsystem ID Hex: The subsystem ID associated with this device.

Time Stamp: The date and time this data was reported. Primarily for use in historical reporting.

Total Phys Read Response Time: The total time to read from the physical disk in milliseconds over the cache interval.

Total Phys Write Response Time: The total time to write to the physical disk in milliseconds over the cache interval.

User DASD Grp Name: The name of the user DASD group to which this volume belongs.

User Group Index: A user DASD group is an OMEGAMON construct that enables you to define groups of DASD volumes by VOLSER or device address. You may also specify generic visors and devices (patterns) by using a wildcard character.

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

Write Hit Percent: The percent of I/O WRITE operations which were satisfied without having to access the physical drive. This occurs as the result of DASD Fast Write or Cache Fast Write features. DASD Fast Write is a default in controllers that support it. Cache Fast Write may be requested in the Define Extent command of the channel program.

Write I/O Count: The number of WRITE requests for this device.