Default settings of log rotation need tuning to avoid log records to be overwritten very quickly. Maybe R80.20 3.10 kernel Gaia is the version with increased limits, I am testing it in a lab and defaults seem to be more generous they used to be up to R80.10.
Until R80.10 the /var/log messages gets rotated as soon as the size of the file reaches 64kB and only 4 rotated files are kept.
You may want to increase size limits and number of the rotated files (in the example below the messages file would be about 1MB and 9 rotated files would be kept):
log_start limit 0 1048576 9
Syntax:
log_start limit <log-index> <max-size> <backlog-copies>
To see all the files managed by CP rotation and their settings:
log_start list