Modes, Roles, and States
The mode of an EMS server is determined by its configuration, and dictates how it operates in its environment. If a fault tolerant mode is selected, two EMS servers are required and each operates in a defined role. How an EMS server is operating at any given moment can be determined by viewing its fault tolerant state.
For example, an EMS server operating in fault tolerant mode can play either a primary or secondary role. Once both EMS servers in the fault tolerant pair have been started, one of the two servers will be in the active state while its peer will be in the standby state. In the event of a failover, the server that was standby becomes active.
Modes
By default, the EMS server operates in standalone mode. However, it can also be configured to run in a fault tolerant mode:
- Standalone — the default EMS server mode.
- Classic Fault Tolerant — configured through the
ft_active
parameter if using file-based stores or grid stores and through the FTL configuration if using FTL stores.
Roles
Each server operating in a fault tolerant mode has a distinct role: primary or secondary.
These roles are implicit for EMS servers started using
tibemsd.conf files. They are explicit for EMS servers started using a JSON configuration file. For JSON-configured servers, the primary server is the EMS server started without the
-secondary
command line parameter, while the secondary server is started with it. In the
.conf
files, each server in the fault tolerant pair has a distinct
tibemsd.conf
file.
States
The state of the EMS server tells you about its current operations.
Use the
info
or
show state
command in the administration tool to determine the state of the EMS server.
State | Description |
---|---|
active
|
The server is fully operational and ready to service clients. |
standby
|
The server is in classic fault tolerant mode and is ready to take over should its peer fail. |