Explain the significance of pgp num & how it differs from pg num.
Fixes: #10035
Reported-by: Loic Dachary <loic@dachary.org>
Signed-off-by: Abhishek Lekshmanan <abhishek.lekshmanan@ril.com>
undersized not valid: undersized not in inactive|unclean|stale
undersized not valid: undersized doesn't represent an int
Invalid command: unused arguments: ['undersized']
pg dump_stuck {inactive|unclean|stale [inactive|unclean|stale...]} {<int>} : show information about stuck pgs
Signed-off-by: xinxin shu <xinxin.shu@intel.com>
When a cluster has few OSDs (less than 50) propose a preselection of
values: as long as the number of placement groups is not too small nor
too large, it won't make much of a difference anyway.
Users of small clusters tend to blindly apply the (OSD*100)/(pool size)
formula and worry about chosing a wrong value because they do not
understand the tradeoffs. The preselection will hopefully save them from
this uncertainty.
Add an explanation of how placement groups relate to OSDs, CRUSH and
pools to help understand the tradeoffs. Explain the
tradeoffs (durability, distribution and resource usages) with examples.
Signed-off-by: Loic Dachary <loic-201408@dachary.org>
Reviewed-by: Gerben Meijer <infernix@gmail.com>
Reviewed-by: Laurent Guerby <laurent@guerby.net>
Previous commit (047287afbe) broke
formatting on the formula, and also made mixed formula and text oddly,
which on second thought didn't look too good.
Add the note about the power of two to the following paragraph
instead, in prose.
Signed-off-by: Florian Haas <florian@hastexo.com>
Following an IRC discussion, it emerged that it would be helpful
to explain the merit of choosing a number of PGs per pool that is
a power of two, to keep PGs at roughly equal sizes in case of
PG splits.
See http://irclogs.ceph.widodh.nl/index.php?date=2014-03-12 for the
original discussion.
Signed-off-by: Florian Haas <florian@hastexo.com>
