Compaq Reliable Transaction Router manual 13 Transactional Shadowing Configuration

RTR Terminology

Figure 1–13 Transactional Shadowing Configuration

FE

TR

BE

Server

BE

Server

Primary

Server

Shadow

Server

LKG-11211-98WI

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.

1–14Introduction