Comment 2 for bug 1185689

Jervin, since at the moment GCache is size-based, there can be no straightforward way to tell for how long it will last - clearly it depends on the replication rate. And that not only varies from site to site but also from time to time. So yes, it is not easy, but it probably cannot be.

I'd suggest that the right approach here should be not "how many hours will it hold", but "at what size using SST would be preferable to IST".