Help

 

System Managed Storage Data

The SMS section of the Data Set Characteristics report enables you to identify ways to reclassify a data set through System Managed Storage (SMS) to improve its performance.

For VSAM, Strobe may not always provide SMS information. For example, if Strobe could not determine the data set's cluster name, it cannot provide SMS information. If only the component name is available and the component name has a last qualifier '.INDEX,' '.DATA', or '.D', Strobe assumes that the file's cluster name is the component name without the last qualifier and attempts to find information for the cluster name.

Strobe does not collect SMS information for alternate indexes. SMS will assign an alternate index the same management class and storage class as its associated base cluster.

  • Data class is the data class to which SMS assigns a data set. DATA CLASS contains a collection of allocation and space attributes for a group of data sets. The storage administrator defines the attributes.

  • Management class is the management class to which a data set is assigned. MANAGEMENT CLASS displays a collection of management attributes that control:

  • The release of allocated but unused space.

  • The retention, migration, and backup of data sets.

  • The retention and backup of aggregate groups.

  • The retention, backup, and class transition of objects.

The storage administrator defines these attributes.

  • Storage class shows the storage class to which a data set is assigned. STORAGE CLASS provides a named list of storage attributes that identify performance goals and availability requirements as defined by the storage administrator. It provides the criteria that SMS uses to determine an appropriate location for a data set or object.

  • MSR identifies the millisecond response (MSR) objective defined for this data set. MSR is defined for both direct and sequential processing modes and is reported as a three-digit value from 000 through 999.

Must Cache data sets are identified by MSR values that cannot be met without the use of cache. May Cache data sets are identified by a value of 000 (indicating that no MSR was specified) or a value that can be met without the use of cache. Never Cache data sets are identified by a value of 999.

Hint: Compare this value with the value identified in the RESP field (average response time) to see if the data set is caching as you would expect, given the specified MSR.

Bias identifies the BIAS value defined for the data set. BIAS is defined for both direct and sequential processing modes. The possible values for this field are READ, WRITE, or NONE.

More about the Data Set Characteristics report