diff --git a/archive_test.go b/archive_test.go
index 28392f3..0e335d0 100644
--- a/archive_test.go
+++ b/archive_test.go
@@ -1,42 +1,29 @@
 package main
 
 import (
-	"bufio"
-	"os"
+	"log"
 	"testing"
 	"time"
 )
 
-func TestArchiveReadDir(t *testing.T) {
-
-	memoryStore = NewMemoryStore(map[string]MetricConfig{
-		"flops_dp": {Frequency: 5},
-		"flops_sp": {Frequency: 5},
+func TestFromCheckpoint(t *testing.T) {
+	m := NewMemoryStore(map[string]MetricConfig{
+		"cpi":       {Frequency: 5, Aggregation: AvgAggregation},
+		"flops_any": {Frequency: 5, Aggregation: SumAggregation},
+		"flops_dp":  {Frequency: 5, Aggregation: SumAggregation},
+		"flops_sp":  {Frequency: 5, Aggregation: SumAggregation},
 	})
-	data := `{"from":1692628930,"to":1692629003,"metrics":{},"children":{"hwthread0":{"from":1692628930,"to":1692629003,"metrics":{"cpi":{"frequency":5,"start":1692628930,"unit":"","data":[2.2,0.7,2.1,1.6,2.3,0.7,0.9,1.8,0.7,1.7,1.5,1.8,0.9,1.6]},"flops_any":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.3,0.0,0.0,0.0,0.0,28.2,5.1,4.7,0.1,0.3,0.0,0.2,0.0,0.0]},"flops_dp":{"frequency":5,"start":1692628931,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.0,0.0,0.5,0.1,0.0,0.0,0.0,0.0,0.0,0.0,0.0]},"flops_sp":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.3,0.0,0.0,0.0,0.0,27.2,4.8,4.7,0.0,0.3,0.0,0.2,0.0,0.0]}},"children":{}},"hwthread1":{"from":1692628930,"to":1692629003,"metrics":{"cpi":{"frequency":5,"start":1692628930,"unit":"","data":[0.9,4.2,4.2,3.8,3.1,0.7,1.3,0.7,1.8,1.6,5.0,3.0,4.9,5.2]},"flops_any":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.5,0.0,0.0,0.0,0.0,49.8,5.0,0.1,0.0,0.0,0.0,0.0,0.0,0.0]},"flops_dp":{"frequency":5,"start":1692628931,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.0,0.0,0.4,0.1,0.0,0.0,0.0,0.0,0.0,0.0,0.0]},"flops_sp":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.5,0.0,0.0,0.0,0.0,49.1,4.9,0.1,0.0,0.0,0.0,0.0,0.0,0.0]}},"children":{}},"hwthread2":{"from":1692628930,"to":1692629003,"metrics":{"cpi":{"frequency":5,"start":1692628930,"unit":"","data":[1.8,0.9,2.2,2.1,4.3,1.4,0.8,1.0,1.1,1.6,3.9,4.9,2.7,5.1]},"flops_any":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.0,0.0,16.2,4.4,0.0,0.1,0.0,0.0,0.0,0.0,0.0]},"flops_dp":{"frequency":5,"start":1692628931,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.0,0.0,0.1,0.2,0.0,0.0,0.0,0.0,0.0,0.0,0.0]},"flops_sp":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.0,0.0,16.1,3.9,0.0,0.1,0.0,0.0,0.0,0.0,0.0]}},"children":{}},"hwthread3":{"from":1692628930,"to":1692629003,"metrics":{"cpi":{"frequency":5,"start":1692628930,"unit":"","data":[2.0,0.6,6.0,3.5,2.3,0.9,1.2,1.2,1.1,1.0,2.0,0.7,1.1,3.6]},"flops_any":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.0,0.0,1.6,11.5,0.0,0.0,0.0,0.0,0.2,0.0,0.0]},"flops_dp":{"frequency":5,"start":1692628931,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.0,0.0,0.1,0.4,0.0,0.0,0.0,0.0,0.1,0.0,0.0]},"flops_sp":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.0,0.0,1.4,10.6,0.0,0.0,0.0,0.0,0.0,0.0,0.0]}},"children":{}},"hwthread4":{"from":1692628930,"to":1692629003,"metrics":{"cpi":{"frequency":5,"start":1692628930,"unit":"","data":[1.0,1.5,1.3,0.9,0.8,0.8,1.2,1.2,1.4,1.0,0.8,2.3,2.7,0.8]},"flops_any":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.8,0.0,0.0,0.0,0.0,3.4,1.1,2.2,0.4,0.0,0.0,0.0,0.0,0.0]},"flops_dp":{"frequency":5,"start":1692628931,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.0,0.0,0.7,0.3,0.2,0.0,0.0,0.0,0.0,0.0,0.0]},"flops_sp":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.8,0.0,0.0,0.0,0.0,2.0,0.5,1.8,0.4,0.0,0.0,0.0,0.0,0.0]}},"children":{}},"hwthread5":{"from":1692628930,"to":1692629003,"metrics":{"cpi":{"frequency":5,"start":1692628930,"unit":"","data":[0.9,2.3,1.1,0.7,0.8,1.5,1.0,0.9,0.9,1.0,0.8,1.1,1.0,2.0]},"flops_any":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.5,0.0,1.9,0.1,0.3,3.0,13.8,0.0,1.7,1.1,0.0,0.0,0.5,1.0]},"flops_dp":{"frequency":5,"start":1692628931,"unit":"MFLOP/s","data":[0.3,0.0,0.1,0.0,0.2,0.1,0.9,0.0,0.8,0.6,0.0,0.0,0.0,0.0]},"flops_sp":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.0,0.0,1.7,0.0,0.0,2.9,12.0,0.0,0.0,0.0,0.0,0.0,0.5,1.0]}},"children":{}},"hwthread6":{"from":1692628930,"to":1692629003,"metrics":{"cpi":{"frequency":5,"start":1692628930,"unit":"","data":[1.4,0.8,0.8,1.2,1.4,0.8,1.2,1.1,1.5,0.9,1.5,1.5,1.4,0.8]},"flops_any":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.0,0.1,0.0,3.9,10.6,3.0,1.4,7.0,0.0,1.0,0.2,0.0,0.0,0.0]},"flops_dp":{"frequency":5,"start":1692628931,"unit":"MFLOP/s","data":[0.0,0.1,0.0,0.0,0.0,0.1,0.1,0.2,0.0,0.4,0.0,0.0,0.0,0.0]},"flops_sp":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.0,0.0,0.0,3.9,10.6,2.9,1.2,6.6,0.0,0.1,0.2,0.0,0.0,0.0]}},"children":{}},"hwthread7":{"from":1692628930,"to":1692629003,"metrics":{"cpi":{"frequency":5,"start":1692628930,"unit":"","data":[1.2,1.2,1.3,0.8,1.2,1.5,1.0,0.7,1.7,1.8,3.5,0.7,1.5,4.6]},"flops_any":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.3,0.0,2.3,4.7,0.0,12.5,0.7,0.2,0.2,0.0,0.0]},"flops_dp":{"frequency":5,"start":1692628931,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.0,0.0,0.1,0.9,0.0,0.0,0.0,0.0,0.0,0.0,0.0]},"flops_sp":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.3,0.0,2.2,2.8,0.0,12.5,0.7,0.2,0.2,0.0,0.0]}},"children":{}}}}`
 
-	err := os.MkdirAll("./TestArchiveReadDir/testcluster/nuc", 0755)
+	startupTime := time.Now()
+	files, err := m.FromCheckpoint("./testdata/checkpoints", 1692628930)
+	loadedData := m.SizeInBytes() / 1024 / 1024 // In MB
 	if err != nil {
-		t.Error(err)
+		t.Fatal(err)
+	} else {
+		log.Printf("Checkpoints loaded (%d files, %d MB, that took %fs)\n", files, loadedData, time.Since(startupTime).Seconds())
 	}
-	f, err := os.Create("./TestArchiveReadDir/testcluster/nuc/1692628930.json")
-	if err != nil {
-		t.Error(err)
-	}
-	f.WriteString(data)
-	f.Close()
 
-	startupTime := time.Unix(1692628930, 0)
-	files, err := memoryStore.FromCheckpoint("./TestArchiveReadDir", startupTime.Unix())
-	if err != nil {
-		t.Error(err)
-		return
-	}
-	t.Log(files)
-	memoryStore.DebugDump(bufio.NewWriter(os.Stdout), []string{"testcluster", "nuc", "hwthread0"})
-	err = os.RemoveAll("./TestArchiveReadDir")
-	if err != nil {
-		t.Error(err)
-		return
+	if files != 2 {
+		t.Errorf("expected: %d, got: %d\n", 2, files)
 	}
 }
diff --git a/testdata/checkpoints/fritz/f0131/1692628930.json b/testdata/checkpoints/fritz/f0131/1692628930.json
new file mode 100644
index 0000000..72fda9b
--- /dev/null
+++ b/testdata/checkpoints/fritz/f0131/1692628930.json
@@ -0,0 +1 @@
+{"from":1692628930,"to":1692629003,"metrics":{},"children":{"hwthread0":{"from":1692628930,"to":1692629003,"metrics":{"cpi":{"frequency":5,"start":1692628930,"unit":"","data":[2.2,0.7,2.1,1.6,2.3,0.7,0.9,1.8,0.7,1.7,1.5,1.8,0.9,1.6]},"flops_any":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.3,0.0,0.0,0.0,0.0,28.2,5.1,4.7,0.1,0.3,0.0,0.2,0.0,0.0]},"flops_dp":{"frequency":5,"start":1692628931,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.0,0.0,0.5,0.1,0.0,0.0,0.0,0.0,0.0,0.0,0.0]},"flops_sp":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.3,0.0,0.0,0.0,0.0,27.2,4.8,4.7,0.0,0.3,0.0,0.2,0.0,0.0]}},"children":{}},"hwthread1":{"from":1692628930,"to":1692629003,"metrics":{"cpi":{"frequency":5,"start":1692628930,"unit":"","data":[0.9,4.2,4.2,3.8,3.1,0.7,1.3,0.7,1.8,1.6,5.0,3.0,4.9,5.2]},"flops_any":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.5,0.0,0.0,0.0,0.0,49.8,5.0,0.1,0.0,0.0,0.0,0.0,0.0,0.0]},"flops_dp":{"frequency":5,"start":1692628931,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.0,0.0,0.4,0.1,0.0,0.0,0.0,0.0,0.0,0.0,0.0]},"flops_sp":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.5,0.0,0.0,0.0,0.0,49.1,4.9,0.1,0.0,0.0,0.0,0.0,0.0,0.0]}},"children":{}},"hwthread2":{"from":1692628930,"to":1692629003,"metrics":{"cpi":{"frequency":5,"start":1692628930,"unit":"","data":[1.8,0.9,2.2,2.1,4.3,1.4,0.8,1.0,1.1,1.6,3.9,4.9,2.7,5.1]},"flops_any":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.0,0.0,16.2,4.4,0.0,0.1,0.0,0.0,0.0,0.0,0.0]},"flops_dp":{"frequency":5,"start":1692628931,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.0,0.0,0.1,0.2,0.0,0.0,0.0,0.0,0.0,0.0,0.0]},"flops_sp":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.0,0.0,16.1,3.9,0.0,0.1,0.0,0.0,0.0,0.0,0.0]}},"children":{}},"hwthread3":{"from":1692628930,"to":1692629003,"metrics":{"cpi":{"frequency":5,"start":1692628930,"unit":"","data":[2.0,0.6,6.0,3.5,2.3,0.9,1.2,1.2,1.1,1.0,2.0,0.7,1.1,3.6]},"flops_any":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.0,0.0,1.6,11.5,0.0,0.0,0.0,0.0,0.2,0.0,0.0]},"flops_dp":{"frequency":5,"start":1692628931,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.0,0.0,0.1,0.4,0.0,0.0,0.0,0.0,0.1,0.0,0.0]},"flops_sp":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.0,0.0,1.4,10.6,0.0,0.0,0.0,0.0,0.0,0.0,0.0]}},"children":{}},"hwthread4":{"from":1692628930,"to":1692629003,"metrics":{"cpi":{"frequency":5,"start":1692628930,"unit":"","data":[1.0,1.5,1.3,0.9,0.8,0.8,1.2,1.2,1.4,1.0,0.8,2.3,2.7,0.8]},"flops_any":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.8,0.0,0.0,0.0,0.0,3.4,1.1,2.2,0.4,0.0,0.0,0.0,0.0,0.0]},"flops_dp":{"frequency":5,"start":1692628931,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.0,0.0,0.7,0.3,0.2,0.0,0.0,0.0,0.0,0.0,0.0]},"flops_sp":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.8,0.0,0.0,0.0,0.0,2.0,0.5,1.8,0.4,0.0,0.0,0.0,0.0,0.0]}},"children":{}},"hwthread5":{"from":1692628930,"to":1692629003,"metrics":{"cpi":{"frequency":5,"start":1692628930,"unit":"","data":[0.9,2.3,1.1,0.7,0.8,1.5,1.0,0.9,0.9,1.0,0.8,1.1,1.0,2.0]},"flops_any":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.5,0.0,1.9,0.1,0.3,3.0,13.8,0.0,1.7,1.1,0.0,0.0,0.5,1.0]},"flops_dp":{"frequency":5,"start":1692628931,"unit":"MFLOP/s","data":[0.3,0.0,0.1,0.0,0.2,0.1,0.9,0.0,0.8,0.6,0.0,0.0,0.0,0.0]},"flops_sp":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.0,0.0,1.7,0.0,0.0,2.9,12.0,0.0,0.0,0.0,0.0,0.0,0.5,1.0]}},"children":{}},"hwthread6":{"from":1692628930,"to":1692629003,"metrics":{"cpi":{"frequency":5,"start":1692628930,"unit":"","data":[1.4,0.8,0.8,1.2,1.4,0.8,1.2,1.1,1.5,0.9,1.5,1.5,1.4,0.8]},"flops_any":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.0,0.1,0.0,3.9,10.6,3.0,1.4,7.0,0.0,1.0,0.2,0.0,0.0,0.0]},"flops_dp":{"frequency":5,"start":1692628931,"unit":"MFLOP/s","data":[0.0,0.1,0.0,0.0,0.0,0.1,0.1,0.2,0.0,0.4,0.0,0.0,0.0,0.0]},"flops_sp":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.0,0.0,0.0,3.9,10.6,2.9,1.2,6.6,0.0,0.1,0.2,0.0,0.0,0.0]}},"children":{}},"hwthread7":{"from":1692628930,"to":1692629003,"metrics":{"cpi":{"frequency":5,"start":1692628930,"unit":"","data":[1.2,1.2,1.3,0.8,1.2,1.5,1.0,0.7,1.7,1.8,3.5,0.7,1.5,4.6]},"flops_any":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.3,0.0,2.3,4.7,0.0,12.5,0.7,0.2,0.2,0.0,0.0]},"flops_dp":{"frequency":5,"start":1692628931,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.0,0.0,0.1,0.9,0.0,0.0,0.0,0.0,0.0,0.0,0.0]},"flops_sp":{"frequency":5,"start":1692628930,"unit":"MFLOP/s","data":[0.0,0.0,0.0,0.3,0.0,2.2,2.8,0.0,12.5,0.7,0.2,0.2,0.0,0.0]}},"children":{}}}}