I'd just learned of (and shared a link to) a related technology, "getters", which similarly hold tight vacuums in various applications for years if necessary:
Those are used in vacuum-sealed windows and glazings (the topic of the post I was commenting to).
There are also moisture scavengers put into cooling applications (refrigerators and A/C) to remove any incidental water from refrigerant, which I suspect operate more like your MSDBs.
Getters can hold tight vacuums for several decades, even! I have many vacuum fluorescent displays from the 70s still working perfectly. As long as the getter spot is shiny and not white, it is holding vacuum fine.
<https://news.ycombinator.com/item?id=43498489>
Those are used in vacuum-sealed windows and glazings (the topic of the post I was commenting to).
There are also moisture scavengers put into cooling applications (refrigerators and A/C) to remove any incidental water from refrigerant, which I suspect operate more like your MSDBs.