System journal files collect a recovery journal containing historical information about OpenTP1 and a user journal containing historical information about UAPs.

An element file is said to be in open status when at least one of its constituent physical files is open, and in close status when none of its constituent physical files are open.

When at least the required number of physical files are open, the element file is said to be usable. When fewer than the required minimum number of physical files are open, the element file is said to be in unusable status. The number of physical files required to constitute an element file is determined by specifications in the system journal service definition:

• jnl_dual=N: 1
• jnl_dual=Y and jnl_singleoperation=Y: 1
• jnl_dual=Y and jnl_singleoperation=N: 2

The following table shows the relationship between element file status and physical file status.

Table 4-3 Relationship between element file status and physical file status

Element file status 1		Element file status 2	Physical file open/close status
Usable/Unusable status		Open/close status
One-system operation available	One-system operation unavailable		System A	System B
Y	Y	Open	Open	Open
Y	N	Open	Open	Close
Y	N	Open	Close	Open
N	N	Close	Close	Close

Legend:

Y: Usable

N: Not usable

When at least one of its constituent element files is open, the file group is said to be in opened status. When none of the element files are open, the file group is said to be in closed status.

When at least the minimum number of element files required for load distribution are open, the file group is said to be available. When fewer than the required minimum number of element files are open, the file group is said to be unavailable.

The number of element files required for load distribution is determined by specifications in the system journal service definition:

• With parallel access facility disabled: 1
• With parallel access facility enabled: Minimum number of dispersed files for parallel access

If the number of available element files falls below the value specified for the jnl_min_file_dispersion operand due to an error or some other reason, the file group will enter closed status. The following table shows the status of file groups, element files, and physical files when an error related to element files occurs.

Table 4-4 Relationship between file statuses when an element file error occurs

Status				File group status	Element file status	Physical file status
Parallel access disabled	Error with non-duplicated system, or errors with both systems A and B			Closed	Closed	Closed
	Error with either system A or B	One-system operation available		Opened	Opened
		One-system operation unavailable		Opened (Reserve)	Closed
Parallel access enabled	Error with non-duplicated system, or errors with both systems A and B			Closed	Closed
	Error with either system A or B	One-system operation available	Usable element files equal to or greater than minimum number of dispersions	Opened	Opened
			Usable element files less than minimum number of dispersions	Opened	Opened
		One-system operation unavailable	Usable element files equal to or greater than minimum number of dispersions	Opened	Closed
			Usable element files less than minimum number of dispersions	Opened (Reserve)	Closed

OpenTP1 manages a file group of system journal files in the online mode in three statuses:

• Current
  The file group is available and is currently subject to journal output; there is always only one file group in this status.
  
• Standby
  The file group is not currently subject to journal output, but it is available and can be switched onto current status.
  Standby status can also be further classified into swappable and nonswappable status:
  
  • Swappable status
    This standby file group is overwritable (contains no journal required for recovery) and has been unloaded (copied to a file by the jnlunlfg command). When swapping occurs, this file group can immediately become the current file group.
    
  • Nonswappable status
    This standby file group is not overwritable and is waiting to be unloaded. When swapping is required, this file group cannot immediately become the current file group.
    
• Reserve
  The file group is on unusable status.
  

At least two file groups are required in current and in standby status (but not necessarily in reserve status).

When OpenTP1 is started normally, the file groups specified in the system journal service definition for which ONL has been specified are opened. Among the opened file groups, the first file group specified is placed on current status, and the rest are placed on standby status. Any file group that cannot be opened or for which ONL was not specified is placed on reserve status. When OpenTP1 is restarted, the previous file group on current status is inherited.

The journal is output to the current file group. When the current file group becomes full, the next file group (on standby status) specified in the system journal service definition is swapped in. If dual journals are used, swapping occurs whenever one of them becomes full. When all file groups in the system journal file become full, journal output resumes in the first file group.

A file group containing a journal required for OpenTP1 recovery is determined to be not overwritable and is protected (a non-overwritable file group cannot be placed on current status).

Once a checkpoint dump is collected by OpenTP1, a non-overwritable file group returns to overwritable status, because the previous journal is no longer needed.