deploy: 32fc3b7ba4702a0068a82bdd0595e2f426967d4d

1 files changed, 12 insertions, 0 deletions

diff --git a/develop/upgrade.html b/develop/upgrade.html
index ae20420c90..aa277b2e63 100644
--- a/develop/upgrade.html
+++ b/develop/upgrade.html
@@ -233,6 +233,18 @@ dpkg -i matrix-synapse-py3_1.3.0+stretch1_amd64.deb
 </li>
 </ul>
 <h1 id="upgrading-to-v1670"><a class="header" href="#upgrading-to-v1670">Upgrading to v1.67.0</a></h1>
+<h2 id="direct-tcp-replication-is-no-longer-supported-migrate-to-redis"><a class="header" href="#direct-tcp-replication-is-no-longer-supported-migrate-to-redis">Direct TCP replication is no longer supported: migrate to Redis</a></h2>
+<p>Redis support was added in v1.13.0 with it becoming the recommended method in
+v1.18.0. It replaced the old direct TCP connections (which was deprecated as of
+v1.18.0) to the main process. With Redis, rather than all the workers connecting
+to the main process, all the workers and the main process connect to Redis,
+which relays replication commands between processes. This can give a significant
+CPU saving on the main process and is a prerequisite for upcoming
+performance improvements.</p>
+<p>To migrate to Redis add the <a href="./workers.html#shared-configuration"><code>redis</code> config</a>,
+and remove the TCP <code>replication</code> listener from config of the master and
+<code>worker_replication_port</code> from worker config. Note that a HTTP listener with a
+<code>replication</code> resource is still required.</p>
 <h2 id="minimum-version-of-poetry-is-now-v120"><a class="header" href="#minimum-version-of-poetry-is-now-v120">Minimum version of Poetry is now v1.2.0</a></h2>
 <p>The minimum supported version of poetry is now 1.2. This should only affect
 those installing from a source checkout.</p>