The Infrastructure pane of the Dynatrace Server Settings dialog box allows you to configure storage location, total session storage, and reserve storage per System Profile, and also automatic deletion of the old sessions.
Old data deletion
AppMon 2018 April Update 7 and later You can set automatic deletion of the old stored sessions. After specified periods stored sessions in the Session Storage will be deleted. Data in Performance Warehouse remains unaffected. This feature deletes PurePaths and memory dumps, so you can use it to fulfill GDPR requirements, as it removes all sensitive data that could be captured.
To activate the feature, select the checkbox, and set the retention period in days. You can set more precise retention period in the server.config.xml file, as you can set the value in minutes instead of days there.
Storage quota for sessions
Total quota vs. reservations per System Profile
Use Total Disk Quota to limit the disk space the AppMon Server can use. When the quota limit is met, the oldest session that is not locked is deleted regardless of the System Profile to which it belongs. If space cannot be freed up, session recording is paused until there is space available.
Use Disk Quota Reservation per System Profile to reserve storage per System Profile and specify System Profile priority in terms of choosing a System Profile from which to delete a session. By making reservations for System Profiles, the oldest from the specific session data is deleted to meet the quota again. System Profiles without a reservation compete for the remaining resources. This means reservations for System Profiles are not simply a sub-quota of the Total Disk Quota.
Quota and reservation limits and dependencies
Total quota lower limit without reservations
The smallest number you can enter for total storage is 20 GB, but you must ensure that other processes don't consume system disk space, which could reduce the amount of total storage to less than the specified amount.
If you consider that the AppMon Server always keeps 5 GB free (or 1 GB in demo/trial settings) and sessions can be as large as 5 GB (depending on the AppMon sizing), it would not make much sense to allow a lower value.
Total quota lower limit with reservations
This can be no lower than 50 GB, for reasons previously stated.
Reservations per System Profile lower limits
This is limited to 20%, which amounts to a 10 GB minimum, considering the total quota is a 50 GB minimum to enable reservations per system profile. Less than 10 GB would result in the deletion of the session that was just written to make room for a new one.
Reservations per System Profile overall limits
It is necessary to preserve a reasonable amount of remaining disk space for the System Profiles that do not have reservations. It is not possible to predict exactly how much is required, and it does not make sense to enforce some limit because the requirements depend on the storage requirements of the individual System Profiles without reservation. The user interface can only issue a general warning when space may be low.
Total storage quota
Select this option to schedule a task that monitors disk space at an interval of 10 seconds and checks whether the following occurs:
- Disk quota is exceeded.
- Minimum free disk space is reached.
For stability reasons, the AppMon Server always keeps free disk space (1 GB for the demo settings and free trial; 5 GB otherwise) that is independent of the total storage quota settings.
Storage quota Per System Profile
The Storage Quota Assignment section of the dialog box allows to define disk space quota per System Profile (percentage of the total setting or part in GB) and shows the current use in GB and the date of the oldest continuous recording session.
The Server takes the following actions if no quota for System Profile are defined:
- If the size of the stored sessions exceeds the quota, the AppMon Server deletes the oldest unlocked sessions first, until conditions are met. As much disk space as required is freed to fall below the quota limit. Only whole sessions can be deleted. Deleting a 50GB session may result in falling significantly below the limit or just a bit below the limit. So never exceeding the limit is not guaranteed, but action is taken as soon as possible.
- If disk space cannot be freed up, for example if all sessions are locked, all ongoing recording sessions including session writers and dump creation stop, and an incident is raised.
- If you reduce quota, unlocked sessions are deleted without warning until quota limits are met.
The Server takes the following actions, if quota for System Profiles are defined:
- If the size of the stored sessions exceeds the disk quota, the AppMon Server deletes the oldest unlocked sessions in the following order:
- From System Profiles without quota.
- From System Profiles with quota until the limit is reached. Because only whole sessions can be deleted, this mat result in falling a little bit below the limit.
- If the disk quota is still exceeded, sessions from System Profile with quota below the limit are deleted.
The following are possible user actions for resolution:
- Increase the disk space quota.
- Unlock sessions to allow the task to delete them.
- If the previous actions are unsuccessful, manually unlock and delete sessions using the AppMon Client, which requires a special procedure.
To the right of the Storage Quota option, you can view the used storage quota, the amount of locked storage, and the currently available disk space. If the specified storage quota is higher than that available, AppMon does not use the entire quota and displays a warning message.
Stored sessions directory
Specify a valid path (Windows, Linux, UNC) for stored sessions.
Make sure the AppMon Server service (the accounts it runs under, for example Local Service) has the necessary rights to the directory. Check the Properties > Security settings tab for the sessions/stored directory in Windows Explorer.
When you map a path to a drive on a Windows computer and the sessions directory, the AppMon Server must be allowed to query the available drive's disk space. Consequently, the right permissions must be set for the entire drive at the root, and not only the sessions folder.