understanding remote snapshots

[nappyrat]

i'm i nthe process of setting up remote snapshots for backup/dr purposes and need to make sure i'm understandng it right.  Currently we have in a remote office a VSA.  It has a volume 'data' already created on it, that currently has 132GB of data on it.  In our main office we have a cluster of physical lefthand units we want to backup the remote data volume to.  so i have 2 volumes

data (primary volume in remote management group)

data-backup (remote volume in main office management group)

so starting out, I should do a snapshot of data and call it like 'base snapshot', then setup a remote snapshot of that back to data-backup.  when i kick that off it should start copying all 132GB of data up to the main office?

Now I will setup a schedule that will snapshot the data volume nightly, and remote snapshot it as well back to the main office nightly.  

My understanding is that the remoet 'data-backup' voluem actually contains no data, and it would all be in the first remote snapshot, so does that mean i have to keep the 'base snapshot' and it's remote equivelant forever?