CaughtUpMarker and gsm directory

[adrem1]

G'day everyone,

my apologies in advance if this has already been asked elsewhere, but I could not find any information.

Some fellow SPOs and I are wondering about the introduction of the empty file CaughtUpMarker within the gsm directory of the db directory belonging to cardano-node.

$NODE_HOME/db/gsm/CaughtUpMarker

This file can be deleted (together with gsm) and will represent itself on node start-up (most likely once tip is reached).

Can someone shed some light on this, please? Which node version introduced this? What is the functionality? Is there a reference to this in the release notes?

Thank you in advance for your responses. Have a great day,

Stef