HP Reliable Transaction Router - Manual (Page 31)

RTR Server Types
Note that one node can contain the primary servers for one key
range and standby servers for another key range to balance
the load across systems. This allows the nodes in a cluster
environment to act as standby for other nodes without having
idle hardware. When setting up a standby server, both servers
must have access to the same journal.
Figure 1–14 Standby Servers
VM-0833A-AI
TR
FE
Terminals Frontends Router Backends Database
BE
Server
application
BE
Standby
application
Client
application
FE
Client
application
FE
Client
application
Transactional
shadow server
The transactional shadow server places all transactions
recorded on the primary server on a second database. The
transactional shadow server can be at the same site or at a
different site, with networking capability available.
When one member of a shadow set fails, RTR remembers
the transactions executed at the surviving site in a journal,
and replays them when the failed site returns. Only after all
journaled transactions are recovered does the recovering site
fully process new online transactions. During recovery, new
transactions are processed at the surviving site and added to the
journal for the recovering site.
Introduction 1–19