Adjust default of ``ram-allocation-ratio`` configuration option

In modern hyper-converged architectures the upstream default of
1.5 does not really fit.

Set to 0.98 to give some headroom on the compute nodes and add
a note about the potential need to adjust this value further.

Change-Id: I64e3379686128dd7f222bdfae133a6c90e8f3ef0
Closes-Bug: #1818234
This commit is contained in:
Frode Nordahl 2019-03-01 22:53:26 +01:00
parent c6c0e46c68
commit fe0ba3b883
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GPG Key ID: 6A5D59A3BA48373F
2 changed files with 6 additions and 2 deletions

View File

@ -217,12 +217,16 @@ options:
at the expense of instance performance.
ram-allocation-ratio:
type: float
default: 1.5
default: 0.98
description: |
The physical ram -> virtual ram ratio to use in the Nova scheduler.
.
Increasing this value will increase instance density on compute nodes
at the potential expense of instance performance.
.
NOTE: When in a hyper-converged architecture, make sure to make enough
room for infrastructure services running on your compute hosts by
adjusting this value.
disk-allocation-ratio:
type: float
default: 1.0

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@ -834,7 +834,7 @@ class NovaCCBasicDeployment(OpenStackAmuletDeployment):
services['apache2'] = conf_file
# Expected default and alternate values
flags_default = 'cpu-allocation-ratio=16.0,ram-allocation-ratio=1.5'
flags_default = 'cpu-allocation-ratio=16.0,ram-allocation-ratio=0.98'
flags_alt = 'cpu-allocation-ratio=32.0,ram-allocation-ratio=3.0'
set_default = {'config-flags': flags_default}
set_alternate = {'config-flags': flags_alt}