Record skipped MMP writes in multihost_history
Once per pass through the MMP thread's loop, the vdev tree is walked to
find a suitable leaf to write the next MMP block to. If no such leaf is
found, the thread sleeps for a while and resumes at the top of the loop.
Add an entry to multihost_history when no leaf can be found, and record
the reason in the error column. The error code for such entries is a
bitfield, displayed in hex:
0x1 At least one vdev (interior or leaf) was not writeable.
0x2 At least one writeable leaf vdev was found, but it had a pending
MMP write.
timestamp = the time in seconds since the epoch when no leaf could be
found originally.
duration = the time (in ns) during which no MMP block was written for
this reason. This does not include the preceeding inter-write period
nor the following inter-write period.
vdev_guid = the number of sequential cycles of the MMP thread looop when
this occurred.
Sample output, truncated to fit:
For records of skipped MMP writes the right-most column, vdev_path, is
reported as "-".
id txg timestamp error duration mmp_delay vdev_guid ...
936 11
1520036441 0 146264
891422313 1740883117838 ...
937 11
1520036441 0 163956
888356657 7320395061548 ...
938 11
1520036442 0 130690
885314969 7320395061548 ...
939 11
1520036442 0
2001068577 882296582 1740883117838 ...
940 11
1520036443 0 161806
882296582 7320395061548 ...
941 11
1520036443 0x2 0
998020546 1 ...
942 11
1520036444 0 136585
998020546 7320395061548 ...
943 11
1520036444 0x2 0
998020257 1 ...
944 11
1520036445 5
2002662964 994160219 1740883117838 ...
945 11
1520036445 0x2
998073118 994160219 3 ...
946 11
1520036447 0 247136
994160219 7320395061548 ...
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes #7212
projects / zfs / commit