I'm looking for ways/options to replicate data between two sites for
disaster recovery. Ideally, I'm looking for something realtime. Using a
SAN and Novell's BCC is too expensive, so I am looking for other ideas.
Some I had:

1) Use RSync, but it would not be real time.

2) Use iSCSI and mirror a local volume to an iSCSI target (Can that be done?
Can an NSS volume be an iSCSI target?).

3) Use DRBD ( www.drbd.org ). I just stumbled across this. Will it work
for this? Can it use NSS volumes?

I thought also about using an NSS snapshot some how, but I see that NSS
snapshots are not supported on Linux.

What other ideas are there? Are any of these really feasible if I have a
daily diff in the data of 100GB? The link between the sites is 6 Mbps.