The best replacement for drbd is gluster.

The best alternatives to drbd are rated as following:
★★★★★  gluster
★★★★  ceph
★★★  mysql replication
★★★  glusterfs
★★  gnbd
★★  galera
★★  mysql cluster
★  ltsp
  nbd
  mmm

Your alternative for drbd is not listed? Suggest!
Speaking about drbd, one probably shouldn't forget about lvm.

Other search terms related to drbd and their ratings are:
★★★★★ lvm
★★★ xen
★★★ ocfs2
★★ gfs2
★ gfs
★ ha
★ openfiler
You have in mind a companion for drbd and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of drbd in all years. Click on graph for more.
drbd
gluster
ceph