The statistics gathered by SMF in ESV records can be very useful for assessing the quality of a tape library. IFHSTATR prints ESV records in date/time sequence. You may find it useful to sort ESV records into volume serial number sequence, device address sequence, or into error occurrence sequence to help analyze the condition of the library.

The IFHSTATR report helps to identify deteriorating media (tapes); occasionally, poor performance from a particular tape drive can also be identified. The TAPE UNIT SERIAL may be used to identify the tape drive that wrote the tape.

An ESV record is written to the SMF data set:

1. When a volume is demounted
2. When a volume is demounted via DDR
3. When a tape drive is off-line
4. When a HALT EOD command is issued
5. When EREP is run

Because an ESV record may be written at other than demount time, more than one record may be written during the time a volume is mounted. Therefore, the number of records for a volume should not be used to determine the number of mounts or uses of a volume.