Biju Nair created HBASE-14215:
---------------------------------
Summary: Default cost used for PrimaryRegionCountSkewCostFunction
is not sufficient
Key: HBASE-14215
URL: https://issues.apache.org/jira/browse/HBASE-14215
Project: HBase
Issue Type: Bug
Components: Balancer
Reporter: Biju Nair
Priority: Minor
Current multiplier of 500 used in the stochastic balancer cost function
`PrimaryRegionCountSkewCostFunction` to calculate the cost of total primary
replication skew doesn't seem to be sufficient to prevent the skews (Refer
HBASE-14110). We would want the default cost to be a higher value so that skews
in primary region replica has higher cost. The following is the test result by
setting the multiplier value to 10000 (same as the region replica rack cost
multiplier) on a 3 Rack 9 RS node cluster which seems to get the balancer
distribute the primaries uniformly.
**Initial Primary replica distribution - using the current multiplier**
r1n10 102
r1n11 85
r1n9 88
r2n10 120
r2n11 120
r2n9 124
r3n10 135
r3n11 124
r3n9 129
**After long duration of read & writes - using current multiplier**
r1n10 102
r1n11 85
r1n9 88
r2n10 120
r2n11 120
r2n9 124
r3n10 135
r3n11 124
r3n9 129
**After manual balancing**
r1n10 102
r1n11 85
r1n9 88
r2n10 120
r2n11 120
r2n9 124
r3n10 135
r3n11 124
r3n9 129
**Increased multiplier for primaryRegionCountSkewCost to 10000**
r1n10 114
r1n11 113
r1n9 114
r2n10 114
r2n11 114
r2n9 113
r3n10 115
r3n11 115
r3n9 115
Setting the `PrimaryRegionCountSkewCostFunction` multiplier value to 10000
should help HBase general use.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
