Which directory holds the SmartLog index files by default?

For R8.10

Create a symbolic link between the default directory /var/log/opt/CPrt-R80/log_indexes and the new directory.

[Expert@HostName:0]# ln -s /absolute_path_to/new_log_index_dir /var/log/opt/CPrt-R80/log_indexes

Explanation: By default, the SmartEvent Log Index files should be stored in the /var/log/opt/CPrt-R80/log_indexes/ directory. The underlying operating system will physically save the SmartEvent Log Index files based on the above symbolic link.

https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solutionid=sk66003

R76

SmartLog creates and uses index files for fast access to log file contents. The index files are located by default at $SMARTLOGDIR/data

https://sc1.checkpoint.com/documents/R76/CP_R76_SmartLog_AdminGuide/html_frameset.htm