Hi, 06.11.2007 12:24,, Alan Brown wrote:: > On Tue, 6 Nov 2007, Arno Lehmann wrote: > >> For the single-spindle tapes, like DLT and LTO, retensioning should >> never be needed. Thus it's only reasonable for the drive firmware to >> not accept this command. > > I can think of a number of instances when retensioning is needed - > particularly if the cartridge has been dropped and the tape pancake has > likely slipped slightly.
Well, I was quite sure I saw a technical document once where it was stated that, for single reel cartridges, retensioning was not necessary because tape tension was actively controlled when moving the tape. Thus, once a tape is loaded and used, the tension would always be correct (implying that, once you read a tape to its (physical) end and rewound it, the tape on the cartridge reel would have the normal tension again). Unfortunately, I can't locate this document any more :-( But IBM, for example, in http://www-1.ibm.com/support/docview.wss?uid=ssg1S7001798&aid=1 states that the Retension bit in the SCSI commands where it could be used is not supported. HP and Quantum don't have corresponding information available. So, even while it might seem a good idea to have retensioning procedure for single reel systems, there are reasons to assume you don't need them. Furthermore, all the manufacturers agree how to handle cartridges you dropped: don't use them (personally, I wouldn't be that strict...) Arno -- Arno Lehmann IT-Service Lehmann www.its-lehmann.de ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
