diff --git a/.gitignore b/.gitignore
index 172e57f11..40404d5d1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -26,3 +26,4 @@ _site
 /docs/.jekyll-metadata
 coverage.txt
 cspell.json
+*~
diff --git a/Makefile b/Makefile
index 14b6792db..3c9ba1d55 100644
--- a/Makefile
+++ b/Makefile
@@ -184,19 +184,19 @@ check-all: fmt vet golangci-lint govulncheck
 clean-checkers: remove-golangci-lint remove-govulncheck
 
 test:
-	go test ./lib/... ./app/...
+	DISABLE_FSYNC_FOR_TESTING=1 go test ./lib/... ./app/...
 
 test-race:
-	go test -race ./lib/... ./app/...
+	DISABLE_FSYNC_FOR_TESTING=1 go test -race ./lib/... ./app/...
 
 test-pure:
-	CGO_ENABLED=0 go test ./lib/... ./app/...
+	DISABLE_FSYNC_FOR_TESTING=1 CGO_ENABLED=0 go test ./lib/... ./app/...
 
 test-full:
-	go test -coverprofile=coverage.txt -covermode=atomic ./lib/... ./app/...
+	DISABLE_FSYNC_FOR_TESTING=1 go test -coverprofile=coverage.txt -covermode=atomic ./lib/... ./app/...
 
 test-full-386:
-	GOARCH=386 go test -coverprofile=coverage.txt -covermode=atomic ./lib/... ./app/...
+	DISABLE_FSYNC_FOR_TESTING=1 GOARCH=386 go test -coverprofile=coverage.txt -covermode=atomic ./lib/... ./app/...
 
 benchmark:
 	go test -bench=. ./lib/...
diff --git a/lib/envutil/envutil.go b/lib/envutil/envutil.go
new file mode 100644
index 000000000..ebba7618a
--- /dev/null
+++ b/lib/envutil/envutil.go
@@ -0,0 +1,19 @@
+package envutil
+
+import (
+	"os"
+	"strconv"
+)
+
+// GetenvBool retrieves the value of the environment variable named by the key,
+// attempts to convert the value to bool type and returns the result. In order
+// for conversion to succeed, the value must be any value supported by
+// strconv.ParseBool() function, otherwise the function will return false.
+func GetenvBool(key string) bool {
+	s := os.Getenv(key)
+	b, err := strconv.ParseBool(s)
+	if err != nil {
+		return false
+	}
+	return b
+}
diff --git a/lib/envutil/envutil_test.go b/lib/envutil/envutil_test.go
new file mode 100644
index 000000000..04eb3b106
--- /dev/null
+++ b/lib/envutil/envutil_test.go
@@ -0,0 +1,37 @@
+package envutil
+
+import (
+	"os"
+	"testing"
+)
+
+func TestGetenvBool(t *testing.T) {
+	f := func(value string, want bool) {
+		t.Helper()
+
+		key := "VM_LIB_ENVUTIL_TEST_GETENV_BOOL"
+		os.Setenv(key, value)
+		defer os.Unsetenv(key)
+
+		if got := GetenvBool(key); got != want {
+			t.Errorf("GetenvBool(%s=%s) unexpected return value: got %t, want %t", key, value, got, want)
+		}
+	}
+
+	f("TRUE", true)
+	f("True", true)
+	f("true", true)
+	f("T", true)
+	f("t", true)
+	f("1", true)
+	f("FALSE", false)
+	f("False", false)
+	f("false", false)
+	f("F", false)
+	f("f", false)
+	f("0", false)
+
+	f("", false)
+	f("unsupported", false)
+	f("tRuE", false)
+}
diff --git a/lib/filestream/filestream.go b/lib/filestream/filestream.go
index a04583256..38b27f4eb 100644
--- a/lib/filestream/filestream.go
+++ b/lib/filestream/filestream.go
@@ -9,6 +9,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/envutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/memory"
 	"github.com/VictoriaMetrics/metrics"
@@ -18,6 +19,8 @@ var disableFadvise = flag.Bool("filestream.disableFadvise", false, "Whether to d
 	"The fadvise() syscall prevents from eviction of recently accessed data from OS page cache during background merges and backups. "+
 	"In some rare cases it is better to disable the syscall if it uses too much CPU")
 
+var disableFSyncForTesting = envutil.GetenvBool("DISABLE_FSYNC_FOR_TESTING")
+
 const dontNeedBlockSize = 16 * 1024 * 1024
 
 // ReadCloser is a standard interface for filestream Reader.
@@ -241,8 +244,10 @@ func (w *Writer) MustClose() {
 	putBufioWriter(w.bw)
 	w.bw = nil
 
-	if err := w.f.Sync(); err != nil {
-		logger.Panicf("FATAL: cannot sync file %q: %d", w.f.Name(), err)
+	if !disableFSyncForTesting {
+		if err := w.f.Sync(); err != nil {
+			logger.Panicf("FATAL: cannot sync file %q: %d", w.f.Name(), err)
+		}
 	}
 	if err := w.st.close(); err != nil {
 		logger.Panicf("FATAL: cannot close streamTracker for file %q: %s", w.f.Name(), err)
diff --git a/lib/fs/fs.go b/lib/fs/fs.go
index 9a451fb24..0a5bb6715 100644
--- a/lib/fs/fs.go
+++ b/lib/fs/fs.go
@@ -11,11 +11,14 @@ import (
 	"sync/atomic"
 	"time"
 
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/envutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/filestream"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
 )
 
+var disableFSyncForTesting = envutil.GetenvBool("DISABLE_FSYNC_FOR_TESTING")
+
 var tmpFileNum atomic.Uint64
 
 // MustSyncPath syncs contents of the given path.
diff --git a/lib/fs/fs_solaris.go b/lib/fs/fs_solaris.go
index b3d880446..fd036198c 100644
--- a/lib/fs/fs_solaris.go
+++ b/lib/fs/fs_solaris.go
@@ -30,9 +30,11 @@ func mustSyncPath(path string) {
 	if err != nil {
 		logger.Panicf("FATAL: cannot open file for fsync: %s", err)
 	}
-	if err := d.Sync(); err != nil {
-		_ = d.Close()
-		logger.Panicf("FATAL: cannot flush %q to storage: %s", path, err)
+	if !disableFSyncForTesting {
+		if err := d.Sync(); err != nil {
+			_ = d.Close()
+			logger.Panicf("FATAL: cannot flush %q to storage: %s", path, err)
+		}
 	}
 	if err := d.Close(); err != nil {
 		logger.Panicf("FATAL: cannot close %q: %s", path, err)
diff --git a/lib/fs/fs_unix.go b/lib/fs/fs_unix.go
index c7308fa37..907082a34 100644
--- a/lib/fs/fs_unix.go
+++ b/lib/fs/fs_unix.go
@@ -23,9 +23,11 @@ func mustSyncPath(path string) {
 	if err != nil {
 		logger.Panicf("FATAL: cannot open file for fsync: %s", err)
 	}
-	if err := d.Sync(); err != nil {
-		_ = d.Close()
-		logger.Panicf("FATAL: cannot flush %q to storage: %s", path, err)
+	if !disableFSyncForTesting {
+		if err := d.Sync(); err != nil {
+			_ = d.Close()
+			logger.Panicf("FATAL: cannot flush %q to storage: %s", path, err)
+		}
 	}
 	if err := d.Close(); err != nil {
 		logger.Panicf("FATAL: cannot close %q: %s", path, err)