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Feature #13805

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A way to reliably determine if system is the primary or secondary in CARP

Added by Christopher Cope almost 2 years ago. Updated 10 months ago.

Status:
New
Priority:
Very Low
Category:
High Availability
Target version:
Start date:
Due date:
% Done:

0%

Estimated time:
Plus Target Version:
Release Notes:
Default

Description

There is no current way, as far as I can tell, to reliably determine if the current system is the primary or secondary.

A few of the current ways include:
  • "Synchronize Config to IP" isn't set it's likely secondary, but isn't certain.
  • Checking the advskew is a good way, but these are sometimes changed, so it isn't 100% either.

My thoughts are to add a setting to System > High Avail. Sync for Primary/Secondary.

This would allow behavior specific to that to be implemented. Such as:
  • Disabling the ability to toggle CARP maintenance mode on the Secondary, to avoid confusion.
  • Auto filling advskew when creating new VIPs
  • etc.

I could write the code and submit a merge request for this, but would appreciate any thoughts / comments on anything I may be missing before I do that.

Actions #1

Updated by Jim Pingle almost 2 years ago

  • Target version set to Future

At the moment I don't see this being worth spending time on.

Having a manual setting is about the only way to make that happen, but even then it's not very helpful.

The synchronize address could be set in cases where people use it (in an unsupported way) to daisy chain config changes from A->B->[...]->n.

If VIP skews are manually managed then any guessing would be inaccurate, and suggestions could be inaccurate as well. Best to leave it as a value the user should obviously manage manually if they choose not to synchronize.

If we ever add an active-active mode, it would be redundant/inaccurate even with a manual setting.

Furthermore, you might want a secondary node or other node in maintenance mode, it's not necessarily an error to do so, so disabling the choice is not a good idea.

Actions #2

Updated by Jim Pingle 10 months ago

  • Category changed from CARP to High Availability
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