HCL Notes/Domino 8.5 Forum (includes Notes Traveler)

However, it can be kept under control:

The size of the 'log.nsf' is dependant on how much is logged to it (various logging levels) and for how long (number of days retained).
To keep the size under control, it is a balance between how much space is made available for the 'log.nsf', and how much information is required to be logged and for how long.

1) There are three levers to control the size of the log.nsf:
- the 'days' value of the 'log' parameter in the notes.ini

- a possible log filter; see Admin Help (Creating log filters)

- the following logging settings:
+ 'Passthru_LogLevel'

+ 'DIIOPLogLevel'

Log_AgentManager	Specifies whether or not the start of agent execution is recorded in the log file and shown on the server console.
Log_DirCat	Logs information about the Directory Catalog task to the Miscellaneous Events view of the log file (LOG.NSF).
Log_Replication	Specifies the level of logging of replication events performed by the current server.
Log_Sessions	Specifies whether individual sessions are recorded in the log file and displayed on the console.
Log_Tasks	Specifies whether the current status of server tasks is recorded in the log file and displayed on the console.
Log_Update	Specifies the level of detail of Indexer events displayed at the server console and in the log file.
Log_View_Events	Specifies whether messages generated when views are rebuilt are recorded in the log file.
Mail_Log_To_MiscEvents	Determines whether all mail event messages are displayed in the Miscellaneous Events view of the log file.

Mail routing	"Logging level" field on the Router/SMTP - Advanced - Controls tab of the Configuration Settings document.
Modem I/O	File - Preferences - User Preferences - Ports - COMx - Trace
Modem script I/0	File - Tools - Preferences - Notes Preferences - Ports - COMx - Trace - Options
Traced network connections	Set a com port option in the Port Setup dialog box.
Web Navigator	The "Retriever log level" field on the Server Tasks - Web Retriever tab of the Server document.

2) In addition, the following can be checked:
- that 'Don't maintain unread marks' is checked in the database properties, together with ensuring that other properties are under control (maintain 'LastAccessed', limit entries in '$UpdatesBy' & '$Revisions' fields etc.)

- perform a "compact -b" on 'log.nsf' daily after 4 AM (when the purging occurs) to compact white space for re-useability.

- after heavy logging for troubleshooting purposes, turn the relevant debugging off, use "compact (-c or -B)" to recover database space, or even create a new 'log.nsf' (shutdown Domino, rename 'log.nsf', start Domino) if really necessary, to resume normal operations Domino logging.

3) Since Notes/Domino 6, there is a way to log high levels for longer periods (volume+length) without seriously sacrificing performance and risks: in order to keep older log information out of the live log.nsf, Server Archiving can be used.
Because the log.nsf is a live 'system' database that is frequently updated, it is not the best candidate for monstrous sizes (performance impact, log integrity risk increased, etc.)

One way of keeping more worth of log is to use archiving (hence to an archive databse as opposed to a live database). Then because the log archive database is not as exposed as the log itself, you can keep a few weeks worth of data there , that you can full text index (FTI), and then set to automatically purge the documents after a few weeks.
The server archiving could be scheduled before the daily 'log.nsf' purging which occurs - by default at 4 AM - by defining the archiving settings (Database Properties) and scheduling "compact log.nsf -A" at 3 AM, for instance.