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Technical Bulletin #497: HTAR Update

Published on: 
January 23, 2015

On January 27–28, the Livermore Computing Data Storage Group will release a new version of HTAR (HPSS Tape Archiver) on all open and secure production machines. HTAR—a utility that combines a flexible file-bundling tool with fast parallel access to high performance storage—allows users to store and selectively retrieve even very large sets of files efficiently. This update to HTAR will provide improved handling of both archive creation and extraction.

Archive Creation

This update adds informative output messages as users create very large HTAR archives (multi-terabyte). During a command (–c) to create an archive, HTAR first scans all the source files and then sequentially reads each source file. For multi-terabyte archives, hours or sometimes days may separate these two events. If a source file is removed between these two operations, has an I/O error, or otherwise becomes inaccessible, HTAR will output the following message:

WARNING: Index entry <n>, Local file <path> was missing or inaccessible and could not be copied to the archive

At the end of the create operation, the output will say:

###WARNING       htar returned non-zero exit status.
                 72 = <htar command line>

The error number 72 means at least one file is missing or cannot be opened, but all other files are copied to storage.  (Other error numbers may occur.)

Archive Extraction

Although extremely rare, a command (–x) to extract on old archives may find a rare instance where a file is missing while HTAR is doing I/O error recovery. If it occurs, HTAR will output the following message:

WARNING: readCallbackCtl: At index entry<n>, archive filename '/dev/null' was found - index filename is <path>
HTAR: x /dev/null, <n> bytes, <n> media blocks 

At the end of the extract operation, the output will say:

WARNING: <n> files were extracted to /dev/null. Files were missing at creation time due to filesystem errors or user removal during the archive operation
###WARNING       htar returned non-zero exit status.
                 65 = <htar command line> 

The error number 65 means data format error, but all other files were extracted from storage successfully. (Other error numbers may occur.)

NOTE: If error 72 occurs during the create operation, later extraction of the archive will be completely normal. Error 65 during its extraction operation will not occur.

More Information

For more information on HTAR, please see Technical Bulletin 273, “HTAR: A New File-Archiving Tool” or Technical Bulletin 328, “HTAR Update” available online. A brief syntax summary is available in the HTAR man pages or by using the command htar–?. For details on all HTAR options, see the HTAR Reference Manual.

PDF of TB497 for download and distribution.