Before you begin

Skip this step if you are not using global resource serialization (GRS) to serialize access to resources. If you have multiple systems connected with global resource serialization, decide now how you want GRS to handle the reserve on the control data set.

Recommendations

These recommendations for setting up resource serialization depend on the volume where the control data set resides and if the volume contains critical data.

• If the volume does not contain other critical data and if real reserves do not cause any shared DASD contention problems, convert the associated SYSTEMS enqueue to a local SYSTEM enqueue, while leaving the hardware reserve in effect. This method gives slightly better DFSMSrmm performance.
  Example: Add the reserve names to the global resource serialization exclusion list as shown in Figure 1. This leaves the real hardware reserve in effect, and causes the associated SYSTEMS enqueue to be converted to a local SYSTEM one. You must specify both the major name (QNAME) and the minor name (RNAME) as shown in Figure 1 when converting the SYSTEMS enqueue to a local SYSTEM enqueue. If you only specify the major name, all enqueues used by DFSMSrmm are converted and you will be unable to run DFSMSrmm on multiple systems.

  Note: In Figure 1, replace cdsid with your selected CDSID, as specified in the EDGRMMxx parmlib member OPTION statement.

  Figure 1. Converting the SYSTEMS enqueue to a local SYSTEM enqueue

  RNLDEF RNL(EXCL) TYPE(SPECIFIC)
  QNAME(SYSZRMM)
  RNAME(MASTER.RESERVE)
  RNLDEF RNL(EXCL) TYPE(SPECIFIC)
  QNAME(SYSZRMM)
  RNAME(MASTER.RESERVE.cdsid)

  The length of RNAME must be exactly 23 characters. If the length of your CDSID is less than 8 characters, we recommend you use a generic entry as described below. Otherwise, you must specify RNAME as a hexadecimal constant: RNAME(X'D4C1E2E3C5D94BD9C5E2C5D9E5C54Bxx..xx4040') where X'D4C1E2E3C5D94BD9C5E2C5D9E5C54B' represents MASTER.RESERVE, and X'xx..xx4040', your CDSID appended with blanks to 8 characters in length.

  If your CDSID contains nondisplayable characters, you must specify RNAME as hexadecimal constant and use two hexadecimal digits to specify each character of the name.

  An alternative to creating multiple exclusion RNL entries is to change the existing definition from SPECIFIC to GENERIC. See Figure 2 for an example.

  Figure 2. Changing an existing definition from SPECIFIC to GENERIC

  RNLDEF RNL(EXCL) TYPE(GENERIC)
  QNAME(SYSZRMM)
  RNAME(MASTER.RESERVE)

• If the volume contains other critical data and real reserves could impact other systems or cause DASD contention problems, convert the RESERVE to a SYSTEMS enqueue. If you do not change your GRSRNLxx parmlib member, DFSMSrmm still functions correctly; but any performance gain from using the real hardware reserve feature is negated by the overhead created from sending the global SYSTEMS enqueue around the GRS ring.
  Example: Add the reserve name to the global resource serialization reserve conversion list as shown in Figure 3 to leave the global SYSTEMS enqueue in effect and remove the real hardware reserve. You must specify both the major name (QNAME) and the minor name (RNAME) as shown in Figure 3 when converting the RESERVE to a SYSTEMS enqueue.

  Note:

  1. Do not convert the reserve if the control data set volume is shared with any other system outside the sysplex.
  2. In Figure 3, replace cdsid with your selected CDSID, as specified in the EDGRMMxx parmlib member OPTION statement.

  Figure 3. Converting the RESERVE to a SYSTEMS enqueue

  RNLDEF RNL(CON) TYPE(SPECIFIC)
  QNAME(SYSZRMM)
  RNAME(MASTER.RESERVE)
  RNLDEF RNL(CON) TYPE(SPECIFIC)
  QNAME(SYSZRMM)
  RNAME(MASTER.RESERVE.cdsid)

  The length of RNAME must be exactly 23 characters. If the length of your CDSID is less than 8 characters, we recommend you use a generic entry as described below. Otherwise, you must specify RNAME as a hexadecimal constant: RNAME(X'D4C1E2E3C5D94BD9C5E2C5D9E5C54Bxx..xx4040') where X'D4C1E2E3C5D94BD9C5E2C5D9E5C54B' represents MASTER.RESERVE, and X'xx..xx4040', your CDSID appended with blanks to 8 characters in length.

  If your CDSID contains nondisplayable characters, you must specify RNAME as hexadecimal constant and use two hexadecimal digits to specify each character of the name.

  An alternative to creating multiple conversion RNL entries is to change the existing definition from SPECIFIC to GENERIC. See Figure 4 for an example.

  Figure 4. Changing an existing SPECIFIC definition to GENERIC

  RNLDEF RNL(CON) TYPE(GENERIC)
  QNAME(SYSZRMM)
  RNAME(MASTER.RESERVE)

  Table 1 is the list of DFSMSrmm resource symbolic names. Do not use GRS to change or alter any of these ENQs, except for the case shown in Figure 4. The resource symbolic names are provided for information only because DFSMSrmm processing manages serialization for you.

  Table 1. DFSMSrmm resource symbolic names

  Major Name	Minor Name	Resource	Scope
  SYSZRMM	HSKP.dsn.volser	Inventory management data set serialization	SYSTEMS
  SYSZRMM	MASTER.RESERVE	DFSMSrmm control data set serialization at startup and when the CDSID is not yet known	SYSTEMS
  SYSZRMM	MASTER.RESERVE.cdsid	DFSMSrmm control data set serialization	SYSTEMS
  SYSZRMM	MHKP.ACTIVE	Serialize inventory management functions on the same DFSMSrmm subsystem	SYSTEM
  SYSZRMM	MHKP.dsn.volser	Inventory management data set serialization	SYSTEMS
  SYSZRMM	RMM.ACTIVE	Ensure only one system run per z/OS image	SYSTEM
  SYSZRMM	BUFFER.CONTROL	Buffer management	STEP
  SYSZRMM	EDGINERS.volser	Serialize volume labeling	SYSTEMS
  SYSZRMM	SHUTDOWN	Serialize DFSMSrmm shutdown and refresh processing	SYSTEM
  SYSZRMM	INACTIVE	Serialize DFSMSrmm activation enabling only a single WTOR to be issued to the operator	SYSTEM
  SYSZRMM	EXIT_IS_ACTIVE	Exit recovery serialization	SYSTEM
  SYSZRMM	WTOR_ENQ	Exit recovery serialization	SYSTEM
  SYSZRMM	WTORIPC	TCP/IP error recovery serialization on CLIENT systems	SYSTEM
  SYSZRMM	EXIT_id_UNAVAIL	Exit recovery serialization where id can be 100, 200, or 300 representing the last three characters of the DFSMSrmm installation exits EDG_EXIT100, EDG_EXIT200, or EDG_EXIT300.	SYSTEM

See z/OS MVS Planning: Global Resource Serialization for additional information about global resource serialization.