6 Working with Trails

A trail is a series of files on disk where Oracle GoldenGate stores the captured changes temporarily to support the continuous extraction and replication of database changes You can use trails to monitor path, tune networks, and data input and output.

This section describes the tasks to set up trails:

Topics:

• Quick Tour of the Receiver Server Home Page
  The Receiver Server is the central control service that handles all incoming trail files.
• Tuning Network Parameters
  The network settings in Receiver Server are for Receiver Server initiated paths and must mirror the ones in Distribution Server. Network parameters include TCP flush byte options, DSCP, ToS, buffer size settings and so on.
• Reviewing the Receiver Server Path Information
  
• Monitoring Paths
  You can monitor the path network statistics from the Receiver Server.

6.1 Quick Tour of the Receiver Server Home Page

The Receiver Server is the central control service that handles all incoming trail files.

The Receiver Server works with the Distribution Server to provide compatibility with the classic remote architecture. The Receiver Server home page shows the condition of the distribution path with one end depicting the Extract and the other end, the Replicat.

You can use the Receiver Server home page to view the path details. Simply click Action, Details to see the path details. To know more, see Monitoring Paths.

6.2 Tuning Network Parameters

The network settings in Receiver Server are for Receiver Server initiated paths and must mirror the ones in Distribution Server. Network parameters include TCP flush byte options, DSCP, ToS, buffer size settings and so on.

You can monitor and fine-tune these parameters depending on your requirements using the Performance Metrics and Distribution Server. However, this applies to Distribution Server if the path is initiated from the Distrbution Server and to Receiver Server when the path is initiated from the Receiver Server.

You can view the network parameters from the Performance Monitor Server Overview page for paths that are initiated from the Distribution Server. If you need to tweak them, go to the Distribution Server and do the following:

1. Click the path Action, Details.
   The Path Information page is displayed.
2. Expand the Advanced Options.

   You’ll see App Options, which contain the TCP Flush Bytes and TCP Flush Seconds values. By default, this value is set to OS Default.

   The TCP Options, include the following parameters:

   • DSCP

   • TOS

   • Nodelay

   • Quick ack

   • Cork

   • System Send Buffer Size

   • System Receiver Buffer Size

3. Click the Edit icon next to Advanced Options, to change any of the these values,.
4. Click Apply to save the changes to the network parameters.

Once you edit the network parameters, do monitor their status changes and messages from the server. You can do so using the Performance Monitor Server. See Monitoring Performance for details.

For paths initiated from the Receiver Server, the network statistics can be tweaked from the Receiver Server by performing the following steps:

1. Click the target-initiated path Action button and select Details.

2. From the Path Information tab, expand the Advanced Options, which has the setting for EoF Delay (centiseconds). You may typically need to edit this setting for non-Linux platfoms.

6.3 Reviewing the Receiver Server Path Information

You can constantly monitor the activity of the path on the Receiver Server Statistics page.

The Statistics tab shows you detailed information about the logical change records (LCRs) and DDLs that were read from trails, LCRs and DDLs sent and received, LCRs and DDLs filtered. It also provides information about the DML types, inserts, updates, upserts, and deletes.

The table information includes the values of LCRs read and sent. You can use the arrows to sort the tables and the search to quickly locate a specific table. The search is case insensitive and starts searching as you type to update the table.

6.4 Monitoring Paths

You can monitor the path network statistics from the Receiver Server.

In the Receiver Server, you’ll see the path depicted in a graphical representation and you can perform the following steps to monitor the selected path:

1. Log in to the Receiver Server home page.
2. Click Action, Details for a running path.
3. Click the Network tab.
   You can review the path statistics from this tab. This page displays the following details:

   • Network Statistics: The network statistics information includes details such as target trail file name, port number, total messages written out, and so on. You can use this information to go back to the Distribution Server and tune the network parameters, if required.

   • File IO Statistics: The file IO statistics include total bytes read, total idle time and so on.