zfs/include
Olaf Faaland 927f40d089 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
2018-05-07 17:19:56 -07:00
..
linux Linux 4.16 compat: get_disk_and_module() 2018-03-14 16:10:38 -07:00
sys Record skipped MMP writes in multihost_history 2018-05-07 17:19:56 -07:00
Makefile.am Kernel header installation should respect --prefix 2014-10-28 09:37:06 -07:00
libnvpair.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
libuutil.h Correct cppcheck errors (#6662) 2017-09-20 12:59:21 -07:00
libuutil_common.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
libuutil_impl.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
libzfs.h Multi-modifier protection (MMP) 2017-07-13 13:54:00 -04:00
libzfs_core.h OpenZFS 7600 - zfs rollback should pass target snapshot to kernel 2017-07-04 15:29:52 -07:00
libzfs_impl.h Multi-modifier protection (MMP) 2017-07-13 13:54:00 -04:00
zfeature_common.h OpenZFS 2932 - support crash dumps to raidz, etc. pools 2017-04-10 10:24:17 -07:00
zfs_comutil.h Illumos #2882, #2883, #2900 2013-09-04 15:49:00 -07:00
zfs_deleg.h Add support for user/group dnode accounting & quota 2016-10-07 09:45:13 -07:00
zfs_fletcher.h DLPX-44812 integrate EP-220 large memory scalability 2016-11-29 14:34:27 -08:00
zfs_namecheck.h OpenZFS 7386 - zfs get does not work properly with bookmarks 2017-01-26 14:42:15 -08:00
zfs_prop.h Check the dataset type more rigorously when fetching properties. 2014-05-06 10:41:46 -07:00
zpios-ctl.h Fix spelling 2017-01-03 11:31:18 -06:00
zpios-internal.h Fix spelling 2017-01-03 11:31:18 -06:00