HAST has just been added to FreeBSD:
HAST allows to transparently store data on two physically separated machines connected over the TCP/IP network. Those two machines together will be called a cluster and each machine is one cluster node. HAST works in Primary-Secondary (Master-Backup, Master-Slave) configuration, which means that only one of the cluster nodes can be active at any given time. Active node will be called Primary node. This is the node that will be able to handle I/O requests to HAST-managed devices. Currently HAST is limited to two cluster nodes in total.
Imagine putting PostgreSQL on a FreeBSD system running ZFS within a cluster running HAST.
Now that’s a great combination of open source solutions.
I saw this as well, it certainly looks interesting, but I wonder how is this different than DRBD? Guess I need to read-up on the implementation, things like whether is is async or sync would make a lot of difference; still looks interesting.
Robert, in broad outline, HAST looks a lot like DRBD for FreeBSD. Like DRBD, it looks like it can return completion if the update has landed in memory, but not disk, on the remote node; written to disk on the remote node, or immediately upon being written on the local node with the remote node being updated asynchronously.