This section describes errors of the following types:
Format errors
Parity errors
Positioning errors
Reading errors
Understanding Format Errors
A tape format problem will occur if:
You have saved files on a release prior to mvBase and are now trying to restore those files on a newer release.
You are trying to restore a tape on a tape device that is set for a different format. For example, the tape is QIC11 and the tape device set to read QIC 24. The tape device must be set for the same format as the tape.
In the above cases, the following message displays:
|
Incorrect tape format! (F)orward space to next file (R)ewind tape and try again (M)ount new tape or change device (Q)uit Enter Selection: |
Type F to continue the restore.
Understanding Parity Errors
Many tape problems are detected as parity errors, which can occur for a number of reasons. Perhaps the most common cause of parity errors is using the wrong block size when copying to and from tape. Dirty tape heads can also cause parity errors. The tape itself might be bad—for instance, dirty heads may have corrupted the data at the time they were written to tape.
The T-CHK command checks the file currently located on a tape for parity errors.
Understanding Positioning Errors
Another problem is that the following EOD message appears unexpectedly:
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[6000] END OF RECORDED DATA |
If you know that the tape is not positioned at the end, perhaps the wrong format has been specified. 1/4-inch tapes made using QIC 24 standard are not interchangeable with the QIC 11 standard. Use the T-STATUS command to check the current tape format setting, and use T-FORMAT to specify the correct tape format.
Understanding Reading Errors
A common problem is not using the proper command to read a tape. Make sure you know what command was used to make the tape, then use the appropriate command to restore it. Obviously, physically labelling tapes is a key part of ensuring that data from tape can be restored.
See Also