Alternate example: DFSMShsm serialization configuration

Now assume that you must place other data on the volume with the journal. Because the volume has other data set activity, you choose to protect the journal with global enqueue serialization instead of volume reserves because global enqueue serialization serializes at the data set level. This allows us to concurrently access the journal as well as any other data sets on the volume. However, while this illustrates the conversion from volume reserves to global enqueue serialization, this implementation is neither recommended or likely to be justified because the journal data set is the single most active data set whenever DFSMShsm is running and the preferred implementation is to place the journal on its own volume. Indicate that you want the journal resource, ARCRJRN, converted from a volume reserve to a global enqueue by placing the journal resource in the RESERVE conversion RNL.

Figure 1 is identical to Figure 1 , except that you have moved the journal into the RESERVE conversion RNL.

The journal resource can be adequately protected by either a global enqueue or a reserve so ensure that the journal is placed in either the exclusion list or the conversion list. If the journal does not appear in either of the lists, DFSMShsm serializes the resource with both a hardware reserve and a global enqueue causing an unnecessary performance degradation.

The RESERVE conversion RNL entries, ARCBACV and ARCMIGV, are meaningful only if the SETSYS DFHSMDATASETSERIALIZATION command has been specified. If SETSYS DFHSMDATASETSERIALIZATION has not been specified, reserves using these resource names are not issued.

Figure 1. Access Priority Name List (Configuration 2)

Note: ARCBACV and ARCMIGV should be converted only if GRS or a GRS-like product propagates enqueues for the SYSDSN resource to all shared systems. Converting these reserves without this cross-system propagation of SYSDSN enqueues removes the necessary cross-system serialization and risks loss of data.

Figure 2 is an example of the GRS RNLDEF statements for Figure 1.

Figure 2. RNLDEF Statements That Define the Alternate Configuration

  RNLDEF RNL(EXCL) TYPE(GENERIC) QNAME(ARCAUDIT)                                   
  RNLDEF RNL(EXCL) TYPE(GENERIC) QNAME(ARCBACK)                                  
  RNLDEF RNL(EXCL) TYPE(SPECIFIC) QNAME(ARCGPA) RNAME('ARCMCDS ')                
  RNLDEF RNL(EXCL) TYPE(SPECIFIC) QNAME(ARCGPA) RNAME('ARCBCDS ')                
  RNLDEF RNL(EXCL) TYPE(SPECIFIC) QNAME(ARCGPA) RNAME('ARCOCDS ')                
  RNLDEF RNL(CON) TYPE(SPECIFIC) QNAME(ARCGPA) RNAME('ARCRJRN ')                 
  RNLDEF RNL(EXCL) TYPE(GENERIC) QNAME(ARCGPAL)                                  
  RNLDEF RNL(EXCL) TYPE(GENERIC) QNAME(ARCUPDT)                                  
  RNLDEF RNL(CON) TYPE(GENERIC) QNAME(ARCBACV)                                   
  RNLDEF RNL(CON) TYPE(GENERIC) QNAME(ARCMIGV)