The Zerto Virtual Manager (ZVM) retains standard-level log files according to the value set in the logging configuration file. By default, a maximum of 150 standard logging level log files with a size of 10 MB each is retained. Once 150 standard-level log files have been created, the ZVM begins to remove the oldest log file as each new log file is created. The information contained in the logs can be lost if the logs are removed by the ZVM too quickly.


When working with Assurestor Support to troubleshoot an issue, it may be helpful to increase the number of ZVM log files that are retained. The time frame covered within the logs varies, depending on the rate the information is written to the log file by the ZVM. A busy environment with more than one paired site, and more than 100 VPGs, will retain a much shorter time frame of log information, compared to a quieter environment with one paired site and less than 25 VPGs.


Follow the directions below to change the ZVM standard log file retention. The log files are saved to the Logs directory contained in the Zerto Virtual Replication installation directory. Open the oldest log file within this directory to determine the time frame currently covered. The time stamp written to the first log line entry within this file will determine the oldest point in time covered by the logs. Since the rate of information generated by the Zerto Virtual Manager will fluctuate, observing the time frame covered at multiple points during a day or week will provide a more accurate estimate of the time frame covered by the logs.Caution: Before you increase the number of ZVM standard log level files retained, ensure that there is sufficient disk space available on the drive that holds the ZVR folder to accommodate the new log files. A single file consumes 10 MB, so increasing the number of log files retained by 100 will use an additional 1 GB.

Increase the number of log files that can be archived on a ZVM machine:

1. Open the ZVM directory (C:\Program Files\Zerto\Zerto Virtual Replication or in a different drive according to the user's selection during installation of ZVR).

2. Within this directory, locate the file named: NLog.config, and create a backup copy of this file.

3. Open and edit the NLog.config file with a text file editor (preferably notepad/notepad++).

4. Here is an example that shows how to double the log files retention: In line 22, change the value of "maxArchiveFiles" from 150 files to 300 files and save the file. (picture attached).

Caution: Zerto does not recommend decreasing the number of logs from the default settings, or changing any other values within the log configuration file. Changing other values within this file may cause issues with the ZVM logging function, and prevent the Zerto Diagnostic Application or Remote Log Collector from collecting logs when requested.

Verify the changes have been applied successfully

The changes will apply as soon as the configuration file is saved. If any unexpected problems occur, replace the NLog.config file with the backup copy.

Note: This procedure will not change the Zerto Virtual Replication Appliance (VRA) log retention settings. Please contact Zerto Support for assistance with VRA log changes.


1. There is no need to restart the ZVM service before or after the fact.

2. To collect the maximum amount of log files during a log collection, please choose an unlimited time frame in the log collection wizard.

3. Changes to the NLOG.config file will get overwritten during upgrades so the process needs to be redone post upgrades.

4. Another option you might want to consider is using the Log Archiver - see attached pdf. This allows you to offload the logs from the ZVM.