Replication Monitor (Troubleshooting)
Replication Monitor provides access to the following information and tasks, which can be used during troubleshooting:
- Agent history and output
- Performance information
- Thresholds, warnings, and alerts
Agent History and Output
Agent history and output from current agent sessions can both provide valuable troubleshooting information. The following list includes each agent, the tabs in Replication Monitor on which it can be found, and a link to a topic that explains how to access these tabs:
- The following agents are associated with publications in Replication Monitor:
- Snapshot Agent
- Log Reader Agent
- Queue Reader Agent
Access information and tasks associated with these agents through the following publication tabs: Warnings and Agents (for Distributors running Microsoft SQL Server 2005) or the Agents tab (for Distributors running previous versions of SQL Server). For more information, see How to: View Information and Perform Tasks for the Agents Associated With a Publication (Replication Monitor).
- The following agents are associated with subscriptions in Replication Monitor:
- Distribution Agent
- Merge Agent
Access information and tasks associated with these agents through the following tabs: Subscription Watch List (available for each Publisher) or the All Subscriptions tab (available for each publication). For more information, see How to: View Information and Perform Tasks for the Agents Associated With a Subscription (Replication Monitor).
SQL Server Management Studio also provides basic monitoring of replication agents. For more information, see How to: Monitor Replication Agents from Management Studio (SQL Server Management Studio).
Replication Monitor allows you to monitor the performance of transactional replication and merge replication in the following ways:
- Setting warnings and thresholds
For more information, see the section "Thresholds, Warnings, and Alerts" in this topic.
- Viewing performance measurements
Replication Monitor displays performance quality values for transactional replication and merge replication in the Current Average Performance and Current Worst Performance columns for publications and the Performance column for subscriptions. For more information, see Monitoring Performance with Replication Monitor.
- Determining latency with tracer tokens (transactional replication)
Transactional replication allows you to measure the latency in a system by inserting a token (a small amount of data) in the transaction log of the publication database and recording how long it takes to arrive at the Distributor and Subscribers. The token also allows you to identify if data is not reaching the Distributor or Subscriber. For more information, see Measuring Latency and Validating Connections for Transactional Replication.
- Viewing detailed synchronization statistics (merge replication)
For merge replication, Replication Monitor displays detailed statistics for each article processed during synchronization, including the amount of time spent in each processing phase (uploading changes, downloading changes, and so on). It can help pinpoint specific tables that are causing slow downs and is the best place to troubleshoot performance issues with merge subscriptions. For more information about viewing detailed statistics, see How to: View Information and Perform Tasks for the Agents Associated With a Subscription (Replication Monitor).
- Estimating the time required for a subscription to catch up (transactional replication)
For transactional replication, Replication Monitor displays information about: the number of transactions in the distribution database that have not yet been distributed to a Subscriber; and the estimated time for distributing these transactions. For more information, see How to: View Information and Perform Tasks for the Agents Associated With a Subscription (Replication Monitor).
Thresholds, Warnings, and Alerts
By default, Replication Monitor displays warnings only for uninitialized subscriptions, but you can enable warnings for other conditions. We recommend that you enable warnings for your topology, so that you are informed about status and performance in a timely manner.
When you enable a warning, you specify a threshold. When that threshold is met or exceeded, a warning is displayed (unless an issue with a higher priority needs to be displayed). In addition to displaying a warning in Replication Monitor, reaching a threshold can also trigger an alert. Replication provides a set of alerts associated with performance thresholds and a second set of alerts that provide information about other agent conditions. For more information, see Setting Thresholds and Warnings in Replication Monitor and Using Alerts for Replication Agent Events.