[Imported] Writing on Hot Standby Server

[sbeadle]

>>Message imported from previous forum - Category:Scripts and Tips<<
User: mchartrand, originally posted: 2018-10-19 20:08:22 Id:165
This is a re-posting from the obsoleted (October 2018) "Schneider Electric Telemetry & SCADA" forum.

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**_FeWo:
Hello,
i have a setup with a Hot-Standby Pair of Servers. Is it possible to write value to the Standby Server?
I have a tool which gets system data of the PC and sends it to ClearSCADA server locally. This tool is installed on each server and shall work independend.
Otherwise i have to send the data of the tool via LAN between the servers (for exchange) to see both datasets updated in ViewX.
Thanks and best regards_**

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AWoodland:
You can read and write to any server that isn't configured as a DMZ server, where your user permissions allow and there are not server-side permission restrictions.

When you read data from a Standby server it comes from the server you're directly connected to, but when you write data (e.g. send a control, change config, insert a value) the server you are connected to proxies it to the Main automatically for you and the resulting change comes back via the normal synchronisation process.

DMZ servers are read-only.

This means that assuming the write was accepted you may need to wait up to 5 seconds before you then read the data back from the server and see a change.

Have you tried it? Any errors?

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**_FeWo:
Meanwhile i got it running. The soloution was to get the servers know each other with editing the hosts file.
So i got two different Datapoints in the server. One is written by Server1 and the other by Server2 no matter which one is Main and which is Standby.
Thanks and best regards._**