Manage IDs

PI SDK-based applications may be unable to resolve tags or will find tags on the wrong server if two Data Archive servers have the same Server ID. PI SDK connections are identified by Server ID. If multiple Data Archive servers on a network have the same ID, PI SDK connection requests could potentially be made to any of the servers with duplicate IDs. This can result in errors or incorrect results.

Data Archive servers are identified by a unique Server ID or GUID. The ID is generated when the server is started up for the first time and is stored in \pi\dat\piserver.dat file as well as in the registry (HKEY_LOCAL_MACHINE\SOFTWARE\PISystem\PI\ServerID).

When a client PI-SDK application initially connects to a Data Archive server, the Server ID is added to the Known Servers Table (KST) in the client computer's system registry:

HKEY_LOCAL_MACHINE\SOFTWARE\PISystem\PI-SDK\1.0\ServerHandles

In subsequent connections, the client compares the Server ID returned from the Data Archive server to the Server ID stored locally in the KST. If the two are different (for example, if the original Data Archive is replaced by a new installation), then a Server ID Mismatch dialog appears and asks you to resolve the mismatch. Typically, you can use the dialog to correct the mismatch by accepting the new Server ID. In some situations you may want to clear entries in the known servers table. See Clear the known servers table.

Normally, there is only one ID for each Data Archive, and that ID is always unique. However, multiple Data Archive servers may get the same ID if you make a copy of a virtual machine image that has a server installed and both machines have the same node name. This results in duplicate IDs, which is not recommended.

If you have duplicate server IDs:

• For Data Archive 2008 and later versions, use piconfig to edit the server ID immediately after starting the new server for the first time. See Generate a new server ID for (for 3.4.375 and later).

• For earlier versions of Data Archive, do not copy over the pisysid.dat file. See Generate a new server ID for a PI Server (for 3.4.370 and earlier).