Multiple hosting of Informix

I. Multi-resident

Multiple-homed (multipleresidency) is the running of multiple online instances on the same host, with each online instance owning and managing its own processes, shared memory, and disk space. Multiple hosting does not mean installing the online software to multiple different directories. OnLine5.0, online7.x, and IDs support multiple hosts, and these different versions of the data inventory servers can reside on the same host.

Because multiple databases can be built in a single online database server, users often do not have to use multiple hosts to meet a wide range of data management requirements. But sometimes in order to meet special requirements, it is found that the use of multiple resides can bring a lot of convenience. For example, the online file (archive) and logical log copies are for the entire database server (in the OnLine7.1 can also be only a dbspace file), rather than for the database, in order to separate some databases to manage use, you can consider the use of multiple-resident.

In summary, using multiple hosts can have the following advantages:

1, Production environment and development environment separate;

2, isolation of very important database;

3. Test the distributed data transactions on a single host.

Multiple hosts can run independently and do not interfere with each other because these different online instances use resources such as different shared memory areas and disk space. The online administrator must specify a different profile for each online instance (through a tbconfig or onconfig environment variable), and specify a distinct value for the following parameter in the configuration file:

1, Rvernum

The different shared memory key values are calculated by setting different servernum,online and are requested from the UNIX operating system to different shared memory segments. The online process and the customer application also attach or locate the shared memory that is required based on the value.

2, RootPath and Rootoffset

The above two parameters are combined to uniquely determine the Rootdbspace initial chunk, making different online use of different disk space. (If you use the same rootpath, note that the value of the Rootoffset for the second online is calculated based on the value of the previous rootsize)

3, Ervername and dbserverallases (OnLine7)

These two parameters enable multiple database servers to connect to each other by name. In OnLine5.0, only one dbservername parameter is provided, and if the Informix-star connection product is not installed, the parameter has no practical effect.

4, Msgpath

This parameter causes the running status of different online instances to be traced to the domicile.

5, Irrorpath and Mirroroffset

If you use a mirror image for Rootdbspaces, the above two parameter defined disk space must not be reused on two servers.