RTR Server Types
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 1–15 Standby Servers
ZKO-GS013-99AI
BE
Server
BE
Standby
TR
FE
Client
FE
Client
FE
Client
DB
Terminals
Frontends (FE) Routers (TR)
Backends (BE)
Database (DB)
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, and must exist in a networked environment.
A transactional shadow server can also have standby servers for
greater reliability. 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 receive new online transactions. Transactional shadowing
is done by partition. A transactional shadow configuration can
have only two members of the shadow set.
Shadow servers are servers on separate backends which handle
the same transactions in parallel on identical copies of the
database.
Introduction 1–17
