What are the restrictions that must be considered when using the Disaster Recovery Center?

1. Can data loss occur?

Data loss is possible during the failover switch from MCS to DRS, since the system needs a few seconds (minimum 30s) to ascertain the break from MRS. Since the DRS is a warm-standby system, it also needs a few seconds to activate local periphery drivers. During this period, value alterations sent from the peripheral units might be lost.
To avoid unnecessary system switching, we need a latency period of 30 seconds.

2. Can parameter settings be lost?

Data loss can occur between two updating cycles, i.e. when alterations of parameters or project data are carried out on the MCS, and the MCS fails between two updating cycles, the DRS will retain the data status before the latest updating cycle without access to the latest alterations carried out on the MCS. This can be prevented by means of manual updating.

3. Can the HDB Archive also be used with the Disaster Recovery System?

The updating of historic data after a break in the connection of the Disaster Recovery System can be carried out only with an Oracle data bank.

4. Which user interfaces are used by the Disaster Recovery System?

WinCC OA Clients: In connection with the Disaster Recovery System, only the WinCC OA standard user interfaces are supported.

In the WinCC OA Documenation for the "Disaster Recovery System" you find additional information for restrictions which may apply.