Compaq Reliable Transaction Router - Manual (Page 24)

RTR Terminology
Figure 1–13 Transactional Shadowing Configuration
LKG-11211-98WI
TR
BE
BE
Server
Server
Primary
Server
Shadow
Server
FE
With transactional shadowing, there is no requirement that
hardware, the data store, or the operating system at different
sites be the same. You could, for example, have one site
running OpenVMS and another running Windows NT; the RTR
transactional commit process would be the same at each site.
Note
Transactional shadowing shadows only transactions
controlled by RTR.
For full redundancy to assure maximum availability, a
configuration could employ both disk shadowing in clusters
at separate sites coupled with transactional shadowing across
sites with standby servers at each site. This configuration is
shown in Figure 1–14. For clarity, not all possible connections
are shown. In the figure, backends running standby servers are
shaded, connected to routers by dashed lines. Only one site (the
upper site) does full disk shadowing; the lower site is the shadow
for transactions, shadowing all transactions being done at the
upper site.
1–14 Introduction