Previous Topic: Override VSAM Defaults for Private Buffer PoolsNext Topic: File Groups

CA-L-Serv › Define Managed Files › Performance Adjustments

Performance Adjustments

You can improve I/O performance for most CA-L-Serv managed files by changing any of the following OPTION parameter values on the ADDFILE command:

What You Can Do

OPTION Value

Considerations

Defer write operations for a record until the VSAM buffer is needed for another operation or the deferred write interval expires.

DEFER
  • Use DEFER only with LSR buffer pools.
  • Speeds updates, deletions, and insertions.
  • The deferred write interval is set through the MAXDORM parameter on the OPTIONS command.
  • The most recent version of a record can be lost if a system problem occurs before the data is physically written to a disk.

Pad short records with blanks until the records are nn bytes long.

MINLEN(nn)
  • MINLEN is a safeguard to the TRIM option because it ensures that clients receive records in the length they expect.
  • Only specify MINLEN when directed to do so by the client documentation.

Trim trailing blanks from the data portion of variable length records.

TRIM
  • Saves disk space by reducing the record length before the record is stored on disk.
  • Never affects the key portion of a record.
  • Do not use TRIM if the VSAM data set has been defined with fixed-length records.

For example, to set performance options for the file DPMFSIF, specify the following command in the CA-L-Serv parameter data set:

ADDFILE DPMFSIF OPTION(TRIM,DEFER) POOL(3)

Important! Misuse of these options can cause serious I/O or other system problems. CA Technologies strongly recommends that you use the default values provided by the client application that uses the file.