dump(8) using snapshot + "recommended" cache

[Andrew Hamilton-Wright]

> I regularly use dump(8) with snapshots to back up my server.
>
> While this seems to have been working perfectly well so far,

Sorry to follow-up my own post; I just realized I hadn't mentioned
any version info.  The docs I am reading are the ones associated
with 7.1-RELEASE; I haven't checked whether this part of the dump
documentation got updated with 7.1 or not.

Thanks,
Andrew.