There is an entry per file in the catalog, a million files at 1k each will cause more catalog space than a thousand  1tb files

As of a few weeks ago we saw our NBU7 catalog explode from 80GB to a peak of 238GB. My initial belief was this was part of us standing up a 2^nd media server for the office which was linked to a Data Domain 630. But after reviewing the historical graphs, it is very clear this increase happened just a couple weeks ago. The obvious thing I started doing 2 weeks ago, is backing up our new Isilon cluster and also introduced these backups to a new Data Domain 670. More specifically, our Isilon which contains around 600 million image files that are less than 128k each.

How in the world could 10TB of image data suddenly cause the catalog to triple in size? Yet previously adding 18TB of data from a new media server (the dd630) didn’t even cause more than a 20GB increase in the catalog ?

I’m at quite a loss here to understand how this increase happened so quickly. The real issue here is that the catalog filesystem has filled up 3 times, causing nbpem to crash, and backups to grind to a halt. The last time this happened had nothing to do with the Isilon backups, but happened as a result of changing the media destination from some existing OS backups to go to a Data Domain 670, instead of their old DSSU locations. The isilon also points to this same DD670. Could that be the real issue here? Is there something different about how the catalog stores information when it resides on a Data Domain?