How does drv: work, and why did realtime history stop resolving after enabling redundancy?

Ignition
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1

Environment: Ignition 8.1, redundant pair (mo-ign22-1 master, mo-ign22-2 backup), history provider IgnitionHistorian, tag provider default.

Before enabling redundancy, my sparklines could query realtime tag paths and history resolved fine, e.g.:
[default]Water/WL15/.../PV.

After enabling redundancy, realtime paths no longer return history for those same tags. I now have to pass explicit historian paths like:
histprov:IgnitionHistorian:/drv:mo-ign22-2:default:/tag:Water/WL15/.../PV.

Core questions:

  1. How is the drv:<GatewayName>:<TagProvider> segment intended to work in redundancy on 8.1?

  2. What configuration governs whether realtime paths resolve to history versus requiring explicit histprov:/drv:/tag:?

  3. In 8.1, is it recommended to rely on realtime paths for history (letting Ignition handle redundancy), or to always build explicit histprov:/drv: paths in Perspective?

  4. Are there known 8.1 issues where failover/promotion causes realtime history resolution to fail while explicit drv: paths still work?

Thanks!

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