Epic Goal

LVMS with thin provisioning creates a thin pool which requires metadata for the block mapping. That is currently fixed constant size which could lead to problems.

The goal of this feature is to improve that. At a minimum, we need a documented way to increase the medata size. This will be a clumsy operation requiring direct node access, executing of lvms commands etc. So we should think about exposing a config options where users can set the metadata size for initial installation and then extend later if needed.

Why is this important?

Its dangerous if the metapool runs full, the system will fail with probably loss of data, and its really hard to recover from that situation.

Requirements

1. provide docs guidance on how set/change the metadata size.
2. Optionally: Provide a way to configure the metapool size on initial installation that is honoured when the thin pool is created.
3. Optionally: Support a way to extend the metapool as long as it is not already full. Shrinking metapool sizes is not supported, as its not supported by LVM.
4. Provide monitoring of the meta pool size and issue warnings/alerts if the pool size is approach critical limits (e.g. 80%, 90%). 

Dependencies (internal and external)

1. Guidance from LVM core team on how to find the right metadata size (current RHEL doc is pretty opaque on this)

Previous Work (Optional):

1. …

Open questions::

1. …

Done Checklist

• CI - CI is running, tests are automated and merged.
• Release Enablement <link to Feature Enablement Presentation>
• DEV - Upstream code and tests merged: <link to meaningful PR or GitHub Issue>
• DEV - Upstream documentation merged: <link to meaningful PR or GitHub Issue>
• DEV - Downstream build attached to advisory: <link to errata>
• QE - Test plans in Polarion: <link or reference to Polarion>
• QE - Automated tests merged: <link or reference to automated tests>
• DOC - Downstream documentation merged: <link to meaningful PR>

Size

Eng: ?

Docs: ? 

QE: ?