Knowledgebase: Using tape drives
Is there a verify after write on BACKUPS???
Posted by Andre Kuehnemund, Last modified by Andre Kuehnemund on 06 March 2017 18:06

Verify is somewhat superfluous, since the tape drive technology itself does an automatic verify after write, and PresSTORE's job aborts if the drive delivers an an error. Although unnecessary, we have added the verify function for the user's peace of mind. However, since it is quite time consuming and complex in the implementation, we have chosen to add it only to the archive and not to the backup, with the rationale that backup is a short term function that can easily be repeated and must be done periodically, as opposed to archive, which is a one time long term thing.

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Comments (3)
Abraham Treadwell
22 June 2014 14:07
Does the verify feature check the contents of the tape against the contents of the directories archived?

Knowing that, what was written to the tape is definitely identical to the contents of the original directories would give certainty that not only the write process was correct, but that the WHOLE process was correct.
Andre Kuehnemund
07 April 2015 12:36
A verify as part of an archive job compares the file on the source storage with the file that was archived to tape or disk - using the archive index to compile a list of all files to be checked.

Using the CLI, one can re-run the verification step. The default command only checks the list of files that were archived against a list of source files. In order to actually read each file and verify its integrity the '-verify 1' switch must be used. For details, please refer to the KB article titled "Repeating Post-Archive Tasks and Clip Generation".
Andre Kuehnemund
06 March 2017 16:44
The verify options in P5 Archive now also include using checksums. The verify method can be selected in the archive plan. The checksum type can be specified in the archive pool settings.
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