fix: heal multiple buckets in bulk (#11029)

makes server startup, orders of magnitude
faster with large number of buckets

cmd/erasure-sets.go

@@ -531,6 +531,31 @@ func (s *erasureSets) Shutdown(ctx context.Context) error {
 	return nil
 }
 
+// MakeMultipleBuckets - make many buckets at once.
+func (s *erasureSets) MakeMultipleBuckets(ctx context.Context, buckets ...string) error {
+	g := errgroup.WithNErrs(len(s.sets))
+
+	// Create buckets in parallel across all sets.
+	for index := range s.sets {
+		index := index
+		g.Go(func() error {
+			return s.sets[index].MakeMultipleBuckets(ctx, buckets...)
+		}, index)
+	}
+
+	errs := g.Wait()
+
+	// Return the first encountered error
+	for _, err := range errs {
+		if err != nil {
+			return err
+		}
+	}
+
+	// Success.
+	return nil
+}
+
 // MakeBucketLocation - creates a new bucket across all sets simultaneously,
 // then return the first encountered error
 func (s *erasureSets) MakeBucketWithLocation(ctx context.Context, bucket string, opts BucketOptions) error {