We would like to have more extensive logging of lfsck actions, dumping to a file rather than being limited to a small buffer.

From LU-8071:

By default, the repairing behaviour will be recorded in Lustre debug log
via label "D_LFSCK". But because Lustre kernel log is in RAM only, and if
you did not dump them periodically, then it will be overwritten.

Rather than using the debuging interface, this should be exposed through the "lctl" tool. Either an option to "lfsck_start", or a new "lctl lfsck_log" control option. Writing to a specified file on the MDS would be sufficient, but the ability to write to syslog could potentially be useful as well.

Also, I would propose that the default behavior be that logging is *enabled*. It is easy enough to go back and delete log files after the fact if they are unneeded... but impossible to track down some of what lfsck has done once the kernel buffer has been exhausted.