Just a quick post here to share a non-obvious tunable for Atempo’s Time Navigator 4.2 regarding archiving and media selection.
Before upgrading from 4.1 to 4.2 Time Navigator’s media selection for archive jobs with standalone drives behaved as expected: If existing partly filled and open cartridges in the associated media pool existed, Time Navigator would request those media be placed in the drives upon the start a new archive operation, effectively only asking for new, unlabeled media to be inserted once the existing media was full.
However, with the upgrade to 4.2 we found that Time Navigator was no longer requesting the existing, partly filled, open cartridges and was instead requesting new, unlabeled media to be inserted into the drives instead! The result of this new behavior was that Time Navigator would use new tapes for every new archive operation, no matter if existing, partly filled and open media was available in the media pool. Basically 4.2’s default behavior was preventing us from filling any archive media unless the particular archive job would happen to be larger than a single tape.
While I don’t know why the functionality changed, I do know what tunable to modify in order to make 4.2 behave like 4.1. The tunable is “check_external_cart_when_recycling“. Setting this tunable to “Yes” has restored the 4.1 behavior, allowing us to make full use of all archive media capacity by only requesting new media when all the existing media in the media pool has been filled.
I believe we only faced this problem because we use standalone archive tape drives that do not have an autoloader or robot nor an “inventory” of online tape. Each tape must be manually loaded. I suspect that if we had an autoloader for our tape drives, that 4.2 would have made the correct/expected selection of media.
I doubt that anyone else is going to face this problem but it took about 3 weeks with Atempo’s R&D department to figure out the problem so I figure if posting here can save anyone that amount of time, then I’ll have done my part!