Lustre 1.6 Operations Manual

■ OBD_RACE: Similar to OBD_FAIL_CHECK. Useful to have multiple processes
execute the same code concurrently to provoke locking races. The first process to
hit OBD_RACE sleeps until a second process hits OBD_RACE, then both
processes continue.
■ OBD_FAIL_ONCE: A flag set on a lustre.fail_loc breakpoint to cause the
OBD_FAIL_CHECK condition to be hit only one time. Otherwise, a fail_loc is
permanent until it is cleared with "sysctl -w lustre.fail_loc=0".
■ OBD_FAIL_RAND: Has OBD_FAIL_CHECK fail randomly; on average every (1 /
lustre.fail_val) times.
■ OBD_FAIL_SKIP: Has OBD_FAIL_CHECK succeed lustre.fail_val times, and then
fail permanently or once with OBD_FAIL_ONCE.
■
OBD_FAIL_SOME: Has OBD_FAIL_CHECK fail lustre.fail_val times, and then
succeed.
23.2.9 Debugging in UML
Lustre developers use gdb in User Mode Linux (UML) to debug Lustre. The lmc and
lconf tools can be used to configure a Lustre cluster, load the required modules,
start the services, and set up all the devices. lconf puts the debug symbols for the
newly-loaded module into /tmp/gdb-localhost.localdomain on the host
machine. These symbols can be loaded into gdb using the source command in gdb.
symbol-file
delete
symbol-file /usr/src/lum/linux
source /tmp/gdb-{hostname}
b panic
b stop
Chapter 23 Lustre Debugging 23-11