Detecting unused objects on the system

To detect an unused object, look at both the last-used date and the last-changed date. Change commands do not update the last-used date unless the commands cause the object to be deleted and created again, or the change operation causes the object to be read as a part of the change.

• Date and time of last change
  • When an object is created or changed, the system time stamps the object, indicating the date and time the change occurred.
• Date of last use
  • The date of last use is only updated once per day (the first time an object is used in a day). The system date is used.
  • An unsuccessful attempt to use an object does not update the last used date. For example, if a user tries to use an object for which the user is not authorized, the date of last use does not change.
  • The date of last use is blank for new objects.
  • When an object that already exists on the system is restored, the date of last use comes from the object on the system. If it does not already exist when restored, the date is blank.
  • Objects that are deleted and re-created during the restore operation lose the date of last use.
  • The last used date for a database file is not updated when the number of members in the file is zero. For example, if you use the Create Duplicate Object (CRTDUPOBJ) to copy objects and there are no members in the database file, the last used date is not updated.
  • The last used date for a database file is the last used date of the file member with the most current last used date.
  • For logical files, the last used date is the last time a logical member (or cursor) was used.
  • For physical files, the last used date is the last time the data in the data space was used through a physical or logical access.
  • Objects that are deleted and re-created during the rename operation lose the date of last use.
• Date of last activity
  • Date of last activity is the last date for which data transfer, session or conversation establishment, or use of the hardware associated with a device description occurred.
  • Because the date of last use is updated when a device, controller status, or both go beyond vary-on pending, the date of last use does not accurately reflect the use of the configuration description. For example, if you set virtual devices, controllers, or both to ONLINE(*YES), although no data transfer or communications are established on the device, the date of last use is updated when an initial program load (IPL) is processing and the device is varied on. However, date of last activity is not updated, which can reflect the accurate use of the configuration description.

The following is additional object usage information provided in the object description:

• Counter of number of days used
  • The count is increased when the date of last use is updated.
  • When an object that already exists on the system is restored, the number of days used comes from the object on the system. If it does not already exist when restored, the count is zero.
  • Objects that are deleted and re-created during the restore operation lose the days used count.
  • The days used count is zero for new objects.
    Note: The IBM® i operating system cannot determine the difference between old and new device files. If you restore a device file on to the system and a device file of that same name already exists, delete the existing file if you want the days used count to be reset to zero. If the file is not deleted, the system will interpret this as a restore operation of an old object and retain the days used count.
  • The days used count for a database file is the sum of the days used counts for all file members. If there is an overflow on the sum, the maximum value (of the days used counts field) is shown.
• Date days used count was reset
  • When the days used count is reset using the Change Object Description (CHGOBJD) command or the Change Object Description (QLICOBJD) API, the date is recorded. The user then knows how long the days used count has been active.
  • If the days used count is reset for a file, all of the members have their days used count reset.

Common situations that can delete the days used count and the last used date are as follows:

• Restoring damaged objects on the system.
• Restoring programs when the system is not in a restricted state.

The Display Object Description (DSPOBJD) command can be used to display a full description of an object. You can use the same command to write the description to an output file. To retrieve the descriptions, use the Retrieve Object Description (RTVOBJD) command.

The Retrieve Member Description (RTVMBRD) command and Display File Description (DSPFD) command provide similar information for members in a file.

Object usage information is not updated for the following object types:

• Alert table (*ALRTBL)
• Authorization list (*AUTL)
• Configuration list (*CFGL)
• Class-of-service description (*COSD)
• Data Dictionary (*DTADCT)
• Double-byte character set dictionary (*IGCDCT)
• Double-byte character set sort (*IGCSRT)
• Double-byte character set table (*IGCTBL)
• Edit description (*EDTD)
• Exit Registration (*EXITRG)
• Filter (*FTR)
• Forms control table (*FCT)
• Folder (*FLR)
• Internet Packet Exchange Description (*IPXD)
• Journal (*JRN)
• Journal receiver (*JRNRCV)
• Library (*LIB)
• Mode description (*MODD)
• Network Server Configuration (*NWSCFG)
• Network Server Description (*NWSD)
• NetBIOS Description (*NTBD)
• Product definition (*PRDDFN)
• Reference code translation table (*RCT)
• Session description (*SSND)
• S/36 machine description (*S36)
• User-defined SQL type (*SQLUDT)
• User queue (*USRQ)