The `cluster.routing.allocation.balance.primary` setting has caused
a lot of confusion in the past while it has very little benefit form a
shard allocatioon point of view. Users tend to modify this value to
evently distribute primaries across the nodes which is dangerous since
a prmiary flag on it's own can trigger relocations. The primary flag for a shard
is should not have any impact on cluster performance unless the high level feature
suffereing from primary hotspots is buggy. Yet, this setting was intended to be a
tie-breaker which is not necessary anymore since the algorithm is deterministic.
This commit removes this setting entriely.
In some situations the shard balanceing weight delta becomes negative. Yet,
a negative delta is always treated as `well balanced` which is wrong. I wasn't
able to reproduce the issue in any way other than useing the real world data
from issue #9023. This commit adds a fix for absolute deltas as well as a base
test class that allows to build tests or simulations from the cat API output.
Closes#9023
`allocation.disable_new_allocation`, `allocation.disable_allocation`, `allocation.disable_replica_allocation`,
in favour for the enable allocation decider which has a single option `allocation.enable` wich can be set to the following values:
`none`, `new_primaries`, `primaries` and `all` (default).
Closes#4488
Lee Hinman
gseng
Michael McCandless
Simon Willnauer
Clinton Gormley
mahdeto
Nik Everett
bleskes
Luca Cavanna
Martijn van Groningen