Investigate log growth and synchronization failures in AEM TarMK Cold Standby

Last update: October 28, 2026

This article explains how to address rapid growth of the tarmk-coldstandby.log file and synchronization failures in Adobe Experience Manager (AEM) TarMK Cold Standby environments, typically caused by excessive DEBUG logging and deep recursive processing.

Description description

Environment

Adobe Experience Manager 6.5 or AEM 6.5 LTS configured with TarMK Cold Standby; confirm the applicable version before using these steps.

Issue/Symptoms

The standby instance’s tarmk-coldstandby.log grows rapidly.
Disk space on the standby instance becomes low or is exhausted.
Cold Standby synchronization fails or stops updating.
The logs contain repeated StackOverflowError entries during synchronization.

Cause

In the documented failure pattern, DEBUG logging records a high volume of segment synchronization activity. The same incident included recurring StackOverflowError entries during recursive segment-reference processing. Confirm both the logger level and the error evidence before applying a fix; these symptoms alone do not establish that every synchronization failure has the same cause.

Resolution resolution

Follow the steps below to resolve the issue:

Increase the JVM thread stack size on the standby instance by adjusting the -Xss JVM option to a larger value, such as 2m. This helps prevent StackOverflowError during deep recursive processing.
Review the logging configuration for Cold Standby components and set the log level for org.apache.jackrabbit.oak.segment.standby.client and related classes to INFO during normal operations.
Enable DEBUG logging only when detailed troubleshooting is required, because excessive DEBUG logging is the primary cause of log file growth.
To modify log levels, use System Console > Sling Log Support and update the configuration for the affected loggers.
If synchronization issues persist, recreate the standby instance from a healthy primary instance to eliminate any accumulated inconsistencies.
Monitor disk usage and log file growth on standby nodes to identify abnormal growth patterns early.
Monitor Cold Standby synchronization by reviewing the available metrics in the AEM OSGi Web Console, including standby synchronization status and the last successful synchronization time.
Verify that log file growth is controlled, Cold Standby synchronization completes successfully, and no further StackOverflowError occurrences are reported.

recommendation-more-help

experience-cloud-kcs-help-kbarticles