Load shared with remote I/O data source
- Last UpdatedAug 13, 2025
- 2 minute read
The analysis for the Load Shared configuration is very similar to the tests completed for the Dedicated Standby configuration. The following figure shows the one used in this validation:
The resources and configuration details are described in the following table:
|
Resources |
Description |
|
Hardware |
Dell Precision 360, 1.0 GB RAM, Pentium 4 CPU 2.8 GHz |
|
Operating System |
Windows XP Pro SP2 for Redundant AppEngine nodes |
|
Configuration |
5 AppEngines and 2 RDIObjects with load sharing between redundancy pair platforms. |
|
DIObject |
ABTCPPLC DIObject |
|
Instances |
1:8 ratio (instances: I/O points) |
|
I/O Change Rate |
3% of I/O points changing every scan |
|
History |
3% of I/O points historized every scan |
|
Alarms |
Total 10 alarms |
|
Scripts per Instance |
3 (1 OnScan, 2 execute every scan) |
|
AppEngine Scan Rate |
1000, 1100, 1200, 1300, and 1400 msec |
|
DIObject Scan Group |
1000, 1200, 1500, 1700, 2600, 3300, 4400, and 4600 msec |
|
Modified Attributes |
Checkpoint period: 10000 Force failover timeout: 240000 Maximum time to maintain good quality after failure: 120000 |
The results shown in the table below present the Failover time, CPU utilization and Memory Usage in different scenarios. This table also contains the CPU load on the node that hosts the I/O Servers.
|
I/O Counts |
Total Failover Time |
CPU Load Avg (%) |
Total Memory Usage |
||||
|
Network Failure |
ForceFail overCMD |
Active Node (post failover) |
Standby Node |
I/O Server Nodes 1, 2 |
Active Node |
Standby Node |
|
|
2500 |
20 sec |
16 sec |
7% |
4% |
7%,10% |
430 MB |
330 MB |
|
5000 |
22 sec |
18 sec |
13% |
4% |
7%,10% |
461 MB |
333 MB |
|
10000 |
29 sec |
23 sec |
19% |
5% |
7%,10% |
555 MB |
362 MB |
|
20000 |
47 sec |
31 sec |
40% |
2% |
11%,15% |
605 MB |
385 MB |
|
30000 |
67 sec |
44 sec |
49% |
6% |
21%,22% |
797 MB |
443 MB |
|
40000 |
88 sec |
75 sec |
55% |
7% |
25%,30% |
814 |
552 MB |
Note: During the transition of the engine from Standby to Active state, the CPU values spike at high levels.
After failover, it will be necessary to restore the system to the original (load-sharing) configuration. The following script example would be used on both nodes and configured as While True with a trigger period of 10 minutes:
if me.redundancy.status == "Active" and
me.redundancy.Partnerstatus == "standby - ready" THEN
me.redundancy.forceFailOverCmd = true;
Endif;