From fe850496ee861ae58a5f5dd07185474a5833d93a Mon Sep 17 00:00:00 2001
From: Sean Klein <sean@oxidecomputer.com>
Date: Wed, 18 Mar 2026 14:40:48 -0700
Subject: [PATCH] Undo disabling synchronous writeback

---
 .../src/db/datastore/db_metadata.rs           | 24 -------------------
 test-utils/src/dev/db.rs                      | 15 ------------
 test-utils/src/dev/mod.rs                     |  2 --
 3 files changed, 41 deletions(-)

diff --git a/nexus/db-queries/src/db/datastore/db_metadata.rs b/nexus/db-queries/src/db/datastore/db_metadata.rs
index 487bc774fdf..e431be668d7 100644
--- a/nexus/db-queries/src/db/datastore/db_metadata.rs
+++ b/nexus/db-queries/src/db/datastore/db_metadata.rs
@@ -2698,10 +2698,6 @@ mod test {
                 .max_sql_memory_mib(32);
         let starter = builder.build().expect("Failed to build CRDB starter");
         let mut instance = starter.start().await.expect("Failed to start CRDB");
-        instance
-            .disable_synchronization()
-            .await
-            .expect("Failed to disable synchronization");
 
         let client =
             instance.connect().await.expect("Failed to connect to CRDB");
@@ -2881,10 +2877,6 @@ mod test {
                 .max_sql_memory_mib(32);
         let starter = builder.build().expect("Failed to build CRDB starter");
         let mut instance = starter.start().await.expect("Failed to start CRDB");
-        instance
-            .disable_synchronization()
-            .await
-            .expect("Failed to disable synchronization");
 
         let client =
             instance.connect().await.expect("Failed to connect to CRDB");
@@ -3025,10 +3017,6 @@ mod test {
                 .max_sql_memory_mib(32);
         let starter = builder.build().expect("Failed to build CRDB starter");
         let mut instance = starter.start().await.expect("Failed to start CRDB");
-        instance
-            .disable_synchronization()
-            .await
-            .expect("Failed to disable synchronization");
 
         let client =
             instance.connect().await.expect("Failed to connect to CRDB");
@@ -3165,10 +3153,6 @@ mod test {
                 .max_sql_memory_mib(32);
         let starter = builder.build().expect("Failed to build CRDB starter");
         let mut instance = starter.start().await.expect("Failed to start CRDB");
-        instance
-            .disable_synchronization()
-            .await
-            .expect("Failed to disable synchronization");
 
         let client =
             instance.connect().await.expect("Failed to connect to CRDB");
@@ -3322,10 +3306,6 @@ mod test {
                 .max_sql_memory_mib(32);
         let starter = builder.build().expect("Failed to build CRDB starter");
         let mut instance = starter.start().await.expect("Failed to start CRDB");
-        instance
-            .disable_synchronization()
-            .await
-            .expect("Failed to disable synchronization");
 
         let client =
             instance.connect().await.expect("Failed to connect to CRDB");
@@ -3467,10 +3447,6 @@ mod test {
                 .max_sql_memory_mib(32);
         let starter = builder.build().expect("Failed to build CRDB starter");
         let mut instance = starter.start().await.expect("Failed to start CRDB");
-        instance
-            .disable_synchronization()
-            .await
-            .expect("Failed to disable synchronization");
 
         let client =
             instance.connect().await.expect("Failed to connect to CRDB");
diff --git a/test-utils/src/dev/db.rs b/test-utils/src/dev/db.rs
index 1e71888637f..7145d1e664b 100644
--- a/test-utils/src/dev/db.rs
+++ b/test-utils/src/dev/db.rs
@@ -643,21 +643,6 @@ impl CockroachInstance {
         client.cleanup().await.context("cleaning up after wipe")
     }
 
-    /// Disables fsync synchronization for the underlying storage layer.
-    ///
-    /// This is not a recommended operation in production, but it can
-    /// drastically improve the performance of test databases.
-    pub async fn disable_synchronization(&self) -> Result<(), anyhow::Error> {
-        let client = self.connect().await.context("connect")?;
-        client.batch_execute(
-            "SET CLUSTER SETTING kv.raft_log.disable_synchronization_unsafe = true"
-        ).await.context("disabling database synchronization")?;
-        client
-            .cleanup()
-            .await
-            .context("cleaning up after changing cluster settings")
-    }
-
     /// Wrapper around [`populate()`] using a connection to this database.
     pub async fn populate(&self) -> Result<(), anyhow::Error> {
         let client = self.connect().await.context("connect")?;
diff --git a/test-utils/src/dev/mod.rs b/test-utils/src/dev/mod.rs
index 5a37ac2549e..6c56eee6af3 100644
--- a/test-utils/src/dev/mod.rs
+++ b/test-utils/src/dev/mod.rs
@@ -132,8 +132,6 @@ async fn setup_database(
     let db_url = database.pg_config();
     info!(&log, "cockroach listen URL: {}", db_url);
 
-    database.disable_synchronization().await.expect("Failed to disable fsync");
-
     // If we populate the storage directory by importing the '.sql'
     // file, we must do so after the DB has started.
     match &storage_source {