[OpenIndiana-discuss] What is the rpool/dump fs?

[hput]

Sorry for the lammer question.  Not finding the info that explains it
easily.  Some with just a pointer, url or the like.

What does it do?  How should I handle it when replicating an oi
backup server... no backups on it at the moment so thought I might
replicate rpool .. I am excepting rpool/swap and possibly rpool/dump
Depending how important to the other zfs fs it is.