BRMS Volume Statistic Information

BRMS volume statistic information is collected during BRMS maintenance. Under the covers, it uses the command PRTERRLOG. Users compare this data with Product Activity Log data and have concerns about differences.

The proper use of BRMS volume statistic information is to identify when a volume is reaching end of useful life or a bad section on the tape has been encountered.  If a volume or cartridge exceeds the criteria, the contents of that cartridge or volume should be copied to a new volume and the old volume removed from the inventory.  BRMS volume session statistics are to be used to determine when a volume exceeds acceptable limits.

BRMS volume session statistics can be collected with the following command:

STRMNTBRM RTVVOLSTAT(*YES)

Under this command, BRMS invokes PRTERRLOG four times, for volume types: 3480, 6390, 2440 and 6380.  An example of one of these commands is as follows:

PRTERRLOG  TYPE(*VOLSTAT) OUTPUT(*OUTFILE) PERIOD((&TIME &DATE) (&CURTIME &CURDATE)) OUTFILE(QTEMP/QA1AEL) OUTMBR(*FIRST *ADD) VOLTYPE(6380) VOLSTAT(*KEEP) VOLSTATTYP(*SESSION)

BRMS uses this information to update WRKMEDBRM and PRTMEDBRM output

The volume session statistics are collected for each volume enrolled in BRMS that have been used on the system, since the last time STRMNTBRM RTVVOLSTAT(*YES) was run. The PRTERRLOG command searches the Product Activity Log (PAL), formerly known as the error log, for statistical and recoverable errors detected by the device or the system, and then updates the BRMS DB file with the new values found for that period.

NOTE: The PAL consists of limited space to record errors. Entries are lost when the PAL wraps. The oldest entries drop off as more current entries are added. Entries can also be lost if there is excessive usage of this space for a single job or multiple jobs running on the system.
      
The sequence of events for a newly added volume, used for a backup and then STRMNTBRM RTVVOLSTAT(*YES) being run, are as follows:

• The volume is added to BRMS media file.
•  A backup is run and statistical and recoverable errors are recorded in the PAL.
• STRMNTBRM RTVVOLSTAT(*YES) is run and fields within the file are updated to record the following:
  • Temp Read Error Total
  • Temp Write Error Total   
  • Bytes Read Total   
  • Bytes Written Total    
  • Current Bytes Written   
  • Maximum Bytes Written
  • Read Retry Total
  • Write Retry Total

If the same volume is written to again, after BRMS maintenance is run, those statistics are updated in BRMS DB file next time the command STRMNTBRM RTVVOLSTAT(*YES) is run.  The current value fields for the last use of the volume are updated for that session period and the total value fields are updated with the previous total plus the current value.

If a volume is expired and removed from the BRMS inventory, the volume's statistical information is removed from the BRMS DB file.  This does not remove the PAL entries or the Lifetime Statistics found on the system in System Service Tools (SST) for that volume.

If the PAL entries and Lifetime Statistics for a volume on the system in SST are deleted, the values in the BRMS DB file are not reset or removed.

NOTE: If Lifetime Statistics exist in SST for a volume and STRMNTBRM RTVVOLSTAT(*YES) was never ran, but the volume has since been expired and reused within BRMS, the number of Current Bytes Written for the volume will be wrong.  A recommendation to avoid this discrepancy would be to run STRMNTBRM RTVVOLSTAT(YES) before the BRMS backup.

Understanding this situation, the volume statistics reported in BRMS can be affected by and are dependent upon the following:

• BRMS PTF Level
• PTFs for PRTERRLOG command
• System PTFs for Tape Support code
• System PTFs for PAL logging
• Tape Device Firmware Level
• BRMS usage

Over the history of the BRMS product life, PTFs and functional changes for all of these areas have occurred.  Specific volume statistic information in BRMS is dependent upon fix level in these areas on your system and device, and BRMS usage.  Application of a PTF or fix in any of these areas does not change past statistical data in the BRMS DB or the PAL.  It is recommended that BRMS users routinely maintain the system and devices, by applying the latest fixes available and practice good BRMS usage.

NOTE: When using non-IBM tape drives or Virtual Tape Libraries (VTLs) , there is no guarantee any of the statistics collected are correct.