diff --git a/packages/lodestar/src/chain/chain.ts b/packages/lodestar/src/chain/chain.ts
index e2661c4b4481..408e5ac3e8df 100644
--- a/packages/lodestar/src/chain/chain.ts
+++ b/packages/lodestar/src/chain/chain.ts
@@ -2,7 +2,6 @@
  * @module chain
  */
 
-import fs from "node:fs";
 import path from "node:path";
 import {
   BeaconStateAllForks,
@@ -22,6 +21,7 @@ import {IBeaconDb} from "../db/index.js";
 import {IMetrics} from "../metrics/index.js";
 import {IEth1ForBlockProduction} from "../eth1/index.js";
 import {IExecutionEngine} from "../executionEngine/index.js";
+import {ensureDir, writeIfNotExist} from "../util/file.js";
 import {CheckpointStateCache, StateContextCache} from "./stateCache/index.js";
 import {BlockProcessor, PartiallyVerifiedBlockFlags} from "./blocks/index.js";
 import {IBeaconClock, LocalClock} from "./clock/index.js";
@@ -305,17 +305,22 @@ export class BeaconChain implements IBeaconChain {
 
   persistInvalidSszValue<T>(type: Type<T>, sszObject: T, suffix?: string): void {
     if (this.opts.persistInvalidSszObjects) {
-      this.persistInvalidSszObject(type.typeName, type.serialize(sszObject), type.hashTreeRoot(sszObject), suffix);
+      void this.persistInvalidSszObject(type.typeName, type.serialize(sszObject), type.hashTreeRoot(sszObject), suffix);
     }
   }
 
   persistInvalidSszView(view: TreeView<CompositeTypeAny>, suffix?: string): void {
     if (this.opts.persistInvalidSszObjects) {
-      this.persistInvalidSszObject(view.type.typeName, view.serialize(), view.hashTreeRoot(), suffix);
+      void this.persistInvalidSszObject(view.type.typeName, view.serialize(), view.hashTreeRoot(), suffix);
     }
   }
 
-  private persistInvalidSszObject(typeName: string, bytes: Uint8Array, root: Uint8Array, suffix?: string): void {
+  private async persistInvalidSszObject(
+    typeName: string,
+    bytes: Uint8Array,
+    root: Uint8Array,
+    suffix?: string
+  ): Promise<void> {
     if (!this.opts.persistInvalidSszObjects) {
       return;
     }
@@ -328,15 +333,11 @@ export class BeaconChain implements IBeaconChain {
     const dirpath = path.join(this.opts.persistInvalidSszObjectsDir ?? "invalid_ssz_objects", dateStr);
     const filepath = path.join(dirpath, `${typeName}_${toHex(root)}.ssz`);
 
-    if (!fs.existsSync(dirpath)) {
-      fs.mkdirSync(dirpath, {recursive: true});
-    }
+    await ensureDir(dirpath);
 
     // as of Feb 17 2022 there are a lot of duplicate files stored with different date suffixes
     // remove date suffixes in file name, and check duplicate to avoid redundant persistence
-    if (!fs.existsSync(filepath)) {
-      fs.writeFileSync(filepath, bytes);
-    }
+    await writeIfNotExist(filepath, bytes);
 
     this.logger.debug("Persisted invalid ssz object", {id: suffix, filepath});
   }
diff --git a/packages/lodestar/src/util/file.ts b/packages/lodestar/src/util/file.ts
index 11280b42520b..d4ff3ca4f98b 100644
--- a/packages/lodestar/src/util/file.ts
+++ b/packages/lodestar/src/util/file.ts
@@ -4,19 +4,29 @@
 
 import fs from "node:fs";
 import path from "node:path";
+import {promisify} from "node:util";
 
-/**
- * Recursively ensures directory exists by creating any missing directories
- * @param {string} filePath
- */
-export function ensureDirectoryExistence(filePath: string): boolean {
-  const dirname = path.dirname(filePath);
-  if (fs.existsSync(dirname)) {
+/** Ensure a directory exists */
+export async function ensureDir(path: string): Promise<void> {
+  try {
+    await promisify(fs.stat)(path);
+  } catch (_) {
+    // not exists
+    await promisify(fs.mkdir)(path, {recursive: true});
+  }
+}
+
+/** Write data to a file if it does not exist */
+export async function writeIfNotExist(filepath: string, bytes: Uint8Array): Promise<boolean> {
+  try {
+    await promisify(fs.stat)(filepath);
+    return false;
+    // file exists, do nothing
+  } catch (_) {
+    // not exists
+    await promisify(fs.writeFile)(filepath, bytes);
     return true;
   }
-  ensureDirectoryExistence(dirname);
-  fs.mkdirSync(dirname);
-  return true;
 }
 
 export function rmDir(dir: string): void {
diff --git a/packages/lodestar/test/unit/util/file.test.ts b/packages/lodestar/test/unit/util/file.test.ts
index 5010aae3ddee..9c89c2edb9e8 100644
--- a/packages/lodestar/test/unit/util/file.test.ts
+++ b/packages/lodestar/test/unit/util/file.test.ts
@@ -1,14 +1,50 @@
-import {assert} from "chai";
-import {ensureDirectoryExistence} from "../../../src/util/file.js";
+import fs from "node:fs";
+import path from "node:path";
+import {expect} from "chai";
+import {ensureDir, writeIfNotExist} from "../../../src/util/file.js";
 
-describe("util/file", function () {
-  const testFilePath = "keys/toml/test_config.toml";
+describe("file util", function () {
+  this.timeout(3000);
+  const dirPath = path.join(".", "keys/toml/test_config.toml");
 
-  it("should create directory needed for file writes", () => {
-    assert.isTrue(ensureDirectoryExistence(testFilePath));
+  describe("ensureDir", function () {
+    it("create dir if not exists", async () => {
+      expect(fs.existsSync(dirPath), `${dirPath} should not exist`).to.be.false;
+      await ensureDir(dirPath);
+      expect(fs.existsSync(dirPath), `${dirPath} should exist`).to.be.true;
+      fs.rmdirSync(dirPath);
+    });
   });
 
-  it("should return true for existing directory", () => {
-    assert.isTrue(ensureDirectoryExistence("src"));
+  describe("writeIfNotExist", function () {
+    const filePath = path.join(dirPath, "test.txt");
+    const data = new Uint8Array([0, 1, 2]);
+    before(async () => {
+      await ensureDir(dirPath);
+    });
+
+    after(() => {
+      fs.rmdirSync(dirPath);
+    });
+
+    it("write to a non-existed file", async () => {
+      expect(fs.existsSync(filePath)).to.be.false;
+      expect(await writeIfNotExist(filePath, data)).to.be.true;
+      const bytes = fs.readFileSync(filePath);
+      expect(new Uint8Array(bytes)).to.be.deep.equals(data);
+
+      // clean up
+      fs.rmSync(filePath);
+    });
+
+    it("write to an existing file", async () => {
+      fs.writeFileSync(filePath, new Uint8Array([3, 4]));
+      expect(await writeIfNotExist(filePath, data)).to.be.false;
+      const bytes = fs.readFileSync(filePath);
+      expect(new Uint8Array(bytes)).not.to.be.deep.equals(data);
+
+      // clean up
+      fs.rmSync(filePath);
+    });
   });
 });
diff --git a/packages/lodestar/test/utils/mocks/chain/chain.ts b/packages/lodestar/test/utils/mocks/chain/chain.ts
index e901a0ed4e58..821199ac70a8 100644
--- a/packages/lodestar/test/utils/mocks/chain/chain.ts
+++ b/packages/lodestar/test/utils/mocks/chain/chain.ts
@@ -132,7 +132,7 @@ export class MockBeaconChain implements IBeaconChain {
     this.reprocessController = new ReprocessController(null);
   }
 
-  persistInvalidSszView(view: TreeView<CompositeTypeAny>, suffix?: string): void {}
+  persistInvalidSszView(_: TreeView<CompositeTypeAny>): void {}
 
   getHeadState(): CachedBeaconStateAllForks {
     return createCachedBeaconStateTest(this.state, this.config);