Replication: ReplicationProcess Advanced Parameter


Creation Date: February 09, 2009
Revision Date: October 12, 2011
Product: DS-System

Summary

This article describes the usage of the ReplicationProcess parameter. It represents:

In specific scenarios, you may see more Replication activities than are actually configured in the ReplicationProcess Parameter for a DS-System (DS-Operator > Setup Menu > Advanced Configurations).

Details

When using Replication, there are at least two DS-Systems in the configured Replication Group. The most common configuration for a Replication Group consists of one production DS-System (e.g. a standalone DS-System) and one replication DS-System (e.g. an N+1 DS-System).

Only production DS-Systems receive data from DS-Clients. Normally, Replication DS-Systems only receive data from the production DS-System(s) in the Replication Group. A Replication DS-System will only send data to the other DS-Systems in the group in case of disasters (data loss) on those DS-Systems.

The ReplicationProcess parameter is configurable at DS-System level for each DS-System in the group. As a result, if a DS-System is configured to start n replication activities, that DS-System will only start n replication activities. However, replication activities (either send or receive) can be triggered from other DS-Systems in the replication group. For this reason, you may see more Replication activities running than the configured ReplicationProcess value for that DS-System.

Scenario: Production Standalone DS-System and Replication N+1 DS-System

Suppose a Production Standalone DS-System is configured to trigger a maximum of 27 replication activities (ReplicationProcess parameter is set to 27). Replication activities are triggered by the "replication check" process after each backup activity. The Replication DS-System (a 3 node N+1) is configured to accept 9 replication activities per node (ReplicationProcess parameter is set to 9 on each node).

Even with the above configuration, the replication activities may not always be balanced. For example, you may encounter scenarios where one N+1 node is running 5 processes, another one is running 13 processes, and another one is running 9 processes. In total you still have 27 replication activities, however some N+1 nodes did not reach their maximum number of replication activities (i.e. 9). As a result of the imbalance, the Replication DS-System may request the production DS-System to trigger additional replication activities, thereby pushing the production DS-System above its configured maximum limit of 27 activities.

If the number of processes is an issue, you can do the following:

This way, your limit of 27 replication activities will be enforced on the standalone DS-System.

WARNING: This is not a recommended configuration for permanent use. In case of a disaster to the standalone production DS-System, you would normally want the N+1 DS-System (which has the most up-to-date data) to trigger replication processes to bring the (replacement) production DS-System back up to the same level.

See Also



The information provided in this document is provided "AS IS", without warranty of any kind. ASIGRA Inc. (ASIGRA) disclaims all warranties, either express or implied. In no event shall ASIGRA or its business partners be liable for any damages whatsoever, including direct, indirect, incidental, consequential, loss of business profits or special damages, even if ASIGRA or its business partners have been advised of the possibility of such damages. © Asigra Inc. All Rights Reserved. Confidential.


PREVNEXT