6.2.1. Adjusting the synchronization speed

PSM synchronizes the content of the hard disk of the primary (master) and secondary nodes in the following cases.

  • When you configure two PSM units to operate in High Availability mode (converting a single node to a high availability cluster),

  • when you replace a node from a cluster, or

  • when recovering from a split-brain situation.

  • Normal data replication (copying incoming data, for example, audit trails from the primary node to the secondary node is not synchronization.

Since this synchronization can take up significant system-resources, the maximal speed of the synchronization is limited, by default, to 10 Mbps. However, this means that synchronizing large amount of data can take very long time, so it is useful to increase the synchronization speed in certain situations —.

To change the limit of the DRBD synchronization rate, navigate to Basic Settings > High Availability > DRBD sync rate limit, and select the desired value. Note the following points before changing the DRBD sync rate limit option.

  • The Basic Settings > High Availability > DRBD sync rate limit option is visible only when synchronization is in progress, or when you have clicked Convert to Cluster but have not rebooted the cluster yet.

  • Changing this option does not change the limit of the data replication speed.

  • Set the sync rate carefully. A high value is not recommended if the load of PSM is very high, as increasing the resources used by the synchronization process may degrade the general performance of PSM. On the other hand, the HA link's speed must exceed the speed of the incoming data, else the web UI might become unresponsive and data loss can occur.

The Basic Settings > High Availability > DRBD status field indicates whether the latest data (including PSM configuration, audit trails, log files, and so on) is available on both PSM nodes. For a description of each possible status, see Section 23.7.1, Understanding PSM cluster statuses.