Bug 1653448 - [OSP13] [Docs] HCI guide contains confusing information on NovaReservedHostMemory parameter
Summary: [OSP13] [Docs] HCI guide contains confusing information on NovaReservedHostMe...
Alias: None
Product: Red Hat OpenStack
Classification: Red Hat
Component: documentation
Version: 13.0 (Queens)
Hardware: Unspecified
OS: Unspecified
Target Milestone: zstream
: 13.0 (Queens)
Assignee: Laura Marsh
QA Contact: RHOS Documentation Team
Whiteboard: docs-accepted
Depends On:
Blocks: 1744162 1744168
TreeView+ depends on / blocked
Reported: 2018-11-26 21:46 UTC by Alberto Rivera Laporte
Modified: 2019-08-21 13:42 UTC (History)
4 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
: 1744162 (view as bug list)
Last Closed: 2019-08-21 13:32:44 UTC
Target Upstream Version:

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Description Alberto Rivera Laporte 2018-11-26 21:46:47 UTC
Description of problem:

OSP13 HCI Documentation Guide Section 4.1.1[0] contains an explanation of the THT parameter definition for 'NovaReservedHostMemory' that appears confusing to a new user.

Current explanation:  

The NovaReservedHostMemory parameter sets how much RAM should be reserved for the Ceph OSD services and per-guest instance overhead on hyper-converged nodes.

Explanation according to the nova.conf[1]: 

# Amount of memory in MB to reserve for the host so that it is always available
# to host processes. The host resources usage is reported back to the scheduler
# continuously from nova-compute running on the compute node. To prevent the
# host
# memory from being considered as available, this option is used to reserve
# memory for the host.

The explanation in Red Hat OSP13 documentation appears to state that 'NovaReservedHostMemory' should also reserve memory used for guests/instances in hyperconverged nodes when the purpose of that parameter is to reserve memory for host processes so that memory it is not used for instances.

Let me know if request is unclear -- Thank you.



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