Central gateway logs missing

A few days after upgrading our central gateway from 8.1.18 to 8.1.26, our gateway log seemed to get truncated, and there were no entries past 5/5. I tossed it up with the upgrade, although it was a few days after. Now I'm looking at the logs, and I have nothing before 11 May 2023 at 11:02:46 EST. Is there a limit at which point the log gets cut off that I possibly was unaware of before? It currently contains 31,530 items. Export of the log reveals the same data, cut off before 5/11 at 11:02.

Any thoughts on what this could be?

Logs as in the system.logs.idb file, the wrapper.log.n files, or the log interface in the web UI?

Just checked the wrapper logs as well, everything starts at 5/11, UI viewer, idb file, and wrapper.

Well, the typical upgrade process wouldn't disturb log files at rest. There are 'truncation' mechanisms for the different log files, but they're totally independent; the log idb file attempts to keep ~50,000 rows (or certain filesize limits), and the wrapper.log file is controlled by the parameters in ignition.conf. So for both to be cut off at the same date suggests it was something outside either mechanism. Did you perform the upgrade by doing an uninstall and then installing the new version? Do you remember any oddities during the installation process? Wherever Ignition is installed, try looking for 'companion' files marked with a timestamp, e.g. there will be an active data/ folder, and then a data_$timestamp/ folder; that would be generated during an uninstall operation. I don't think that an uninstall tries to preserve logs.

If you don't see any such evidence of an uninstall, then I'll blame cosmic rays something else in your environment.