diff --git a/buildlet/gce.go b/buildlet/gce.go
index 889ab0f..2668887 100644
--- a/buildlet/gce.go
+++ b/buildlet/gce.go
@@ -17,6 +17,16 @@
 	"google.golang.org/api/compute/v1"
 )
 
+// GCEGate optionally specifies a function to run before any GCE API call.
+// It's intended to be used to bound QPS rate to GCE.
+var GCEGate func()
+
+func apiGate() {
+	if GCEGate != nil {
+		GCEGate()
+	}
+}
+
 // VMOpts control how new VMs are started.
 type VMOpts struct {
 	// Zone is the GCE zone to create the VM in. Required.
@@ -77,6 +87,10 @@
 
 	prefix := "https://www.googleapis.com/compute/v1/projects/" + projectID
 	machType := prefix + "/zones/" + zone + "/machineTypes/" + conf.MachineType()
+	diskType := "https://www.googleapis.com/compute/v1/projects/" + projectID + "/zones/" + zone + "/diskTypes/pd-ssd"
+	if conf.RegularDisk {
+		diskType = "" // a spinning disk
+	}
 
 	instance := &compute.Instance{
 		Name:        instName,
@@ -90,7 +104,7 @@
 				InitializeParams: &compute.AttachedDiskInitializeParams{
 					DiskName:    instName,
 					SourceImage: "https://www.googleapis.com/compute/v1/projects/" + projectID + "/global/images/" + conf.VMImage,
-					DiskType:    "https://www.googleapis.com/compute/v1/projects/" + projectID + "/zones/" + zone + "/diskTypes/pd-ssd",
+					DiskType:    diskType,
 				},
 			},
 		},
@@ -146,6 +160,7 @@
 		addMeta(k, v)
 	}
 
+	apiGate()
 	op, err := computeService.Instances.Insert(projectID, zone, instance).Do()
 	if err != nil {
 		return nil, fmt.Errorf("Failed to create instance: %v", err)
@@ -157,6 +172,7 @@
 OpLoop:
 	for {
 		time.Sleep(2 * time.Second)
+		apiGate()
 		op, err := computeService.ZoneOperations.Get(projectID, zone, createOp).Do()
 		if err != nil {
 			return nil, fmt.Errorf("Failed to get op %s: %v", createOp, err)
@@ -178,6 +194,7 @@
 	}
 	condRun(opts.OnInstanceCreated)
 
+	apiGate()
 	inst, err := computeService.Instances.Get(projectID, zone, instName).Do()
 	if err != nil {
 		return nil, fmt.Errorf("Error getting instance %s details after creation: %v", instName, err)
@@ -244,6 +261,7 @@
 // returns once it's been requested, not when it's done.
 func DestroyVM(ts oauth2.TokenSource, proj, zone, instance string) error {
 	computeService, _ := compute.New(oauth2.NewClient(oauth2.NoContext, ts))
+	apiGate()
 	_, err := computeService.Instances.Delete(proj, zone, instance).Do()
 	return err
 }
@@ -264,6 +282,7 @@
 	computeService, _ := compute.New(oauth2.NewClient(oauth2.NoContext, ts))
 
 	// TODO(bradfitz): paging over results if more than 500
+	apiGate()
 	list, err := computeService.Instances.List(proj, zone).Do()
 	if err != nil {
 		return nil, err
diff --git a/cmd/coordinator/coordinator.go b/cmd/coordinator/coordinator.go
index c77e005..8949c2e 100644
--- a/cmd/coordinator/coordinator.go
+++ b/cmd/coordinator/coordinator.go
@@ -42,6 +42,7 @@
 	"golang.org/x/oauth2"
 	"golang.org/x/oauth2/google"
 	"google.golang.org/api/compute/v1"
+	"google.golang.org/api/googleapi"
 	"google.golang.org/cloud"
 	"google.golang.org/cloud/compute/metadata"
 	"google.golang.org/cloud/storage"
@@ -220,7 +221,7 @@
 		"builder": []string{st.name},
 		"key":     []string{builderKey(st.name)},
 		"hash":    []string{st.rev},
-		"url":     []string{fmt.Sprintf("http://%v/logs?name=%s&rev=%s&st=%p", externalIP, st.name, st.rev, st)},
+		"url":     []string{fmt.Sprintf("http://farmer.golang.org/logs?name=%s&rev=%s&st=%p", st.name, st.rev, st)},
 	}.Encode()
 	for {
 		st.mu.Lock()
@@ -411,7 +412,7 @@
 
 	io.WriteString(w, "<html><body><h1>Go build coordinator</h1>")
 
-	fmt.Fprintf(w, "<h2>running</h2><p>%d total builds active", numTotal)
+	fmt.Fprintf(w, "<h2>running</h2><p>%d total builds active; VM capacity: %d/%d", numTotal, len(vmCap), cap(vmCap))
 
 	io.WriteString(w, "<pre>")
 	for _, st := range active {
@@ -1009,11 +1010,6 @@
 	go func() {
 		err := buildInVM(conf, st)
 		if err != nil {
-			if st.hasEvent("instance_created") {
-				go deleteVM(projectZone, st.instName)
-			}
-		}
-		if err != nil {
 			fmt.Fprintf(st, "\n\nError: %v\n", err)
 		}
 		st.setDone(err == nil)
@@ -1022,24 +1018,53 @@
 	return st
 }
 
+// We artifically limit ourselves to 60 VMs right now, assuming that
+// each takes 2 CPU, and we have a current quota of 200 CPUs. That
+// gives us headroom, but also doesn't account for SSD or memory
+// quota.
+// TODO(bradfitz): better quota system.
+const maxVMs = 60
+
+var vmCap = make(chan bool, maxVMs)
+
+func awaitVMCountQuota() { vmCap <- true }
+func putVMCountQuota()   { <-vmCap }
+
 func buildInVM(conf dashboard.BuildConfig, st *buildStatus) (retErr error) {
+	st.logEventTime("awaiting_gce_quota")
+	awaitVMCountQuota()
+	defer putVMCountQuota()
+
+	needDelete := false
+	defer func() {
+		if !needDelete {
+			return
+		}
+		deleteVM(projectZone, st.instName)
+	}()
+
+	st.logEventTime("creating_instance")
+	log.Printf("Creating VM for %s, %s", conf.Name, st.rev)
 	bc, err := buildlet.StartNewVM(tokenSource, st.instName, conf.Name, buildlet.VMOpts{
 		ProjectID:   projectID,
 		Zone:        projectZone,
 		Description: fmt.Sprintf("Go Builder building %s %s", conf.Name, st.rev),
 		DeleteIn:    vmDeleteTimeout,
 		OnInstanceRequested: func() {
+			needDelete = true
 			st.logEventTime("instance_create_requested")
 			log.Printf("%v now booting VM %v for build", st.builderRev, st.instName)
 		},
 		OnInstanceCreated: func() {
 			st.logEventTime("instance_created")
+			needDelete = true // redundant with OnInstanceRequested one, but fine.
 		},
 		OnGotInstanceInfo: func() {
 			st.logEventTime("waiting_for_buildlet")
 		},
 	})
 	if err != nil {
+		log.Printf("Failed to create VM for %s, %s: %v", conf.Name, st.rev, err)
 		return err
 	}
 	st.logEventTime("buildlet_up")
@@ -1459,6 +1484,7 @@
 	// partially-different 500.
 	// TODO(bradfitz): revist this code if we ever start running
 	// thousands of VMs.
+	gceAPIGate()
 	list, err := computeService.Instances.List(projectID, zone).Do()
 	if err != nil {
 		return fmt.Errorf("listing instances: %v", err)
@@ -1495,13 +1521,25 @@
 	return nil
 }
 
-func deleteVM(zone, instName string) {
+// deleteVM starts a delete of an instance in a given zone.
+//
+// It either returns an operation name (if delete is pending) or the
+// empty string if the instance didn't exist.
+func deleteVM(zone, instName string) (operation string, err error) {
+	gceAPIGate()
 	op, err := computeService.Instances.Delete(projectID, zone, instName).Do()
+	apiErr, ok := err.(*googleapi.Error)
+	if ok {
+		if apiErr.Code == 404 {
+			return "", nil
+		}
+	}
 	if err != nil {
 		log.Printf("Failed to delete instance %q in zone %q: %v", instName, zone, err)
-		return
+		return "", err
 	}
-	log.Printf("Sent request to delete instance %q in zone %q. Operation ID == %v", instName, zone, op.Id)
+	log.Printf("Sent request to delete instance %q in zone %q. Operation ID, Name: %v, %v", instName, zone, op.Id, op.Name)
+	return op.Name, nil
 }
 
 func hasScope(want string) bool {
@@ -1627,3 +1665,16 @@
 		panic("previously assumed to never fail: " + err.Error())
 	}
 }
+
+// apiCallTicker ticks regularly, preventing us from accidentally making
+// GCE API calls too quickly. Our quota is 20 QPS, but we temporarily
+// limit ourselves to less than that.
+var apiCallTicker = time.NewTicker(time.Second / 5)
+
+func init() {
+	buildlet.GCEGate = gceAPIGate
+}
+
+func gceAPIGate() {
+	<-apiCallTicker.C
+}
diff --git a/dashboard/builders.go b/dashboard/builders.go
index 9e7806f..0ecda55 100644
--- a/dashboard/builders.go
+++ b/dashboard/builders.go
@@ -24,6 +24,8 @@
 	Go14URL     string // URL to built Go 1.4 tar.gz
 	buildletURL string // optional override buildlet URL
 
+	RegularDisk bool // if true, use spinning disk instead of SSD
+
 	env []string // extra environment ("key=value") pairs
 }
 
@@ -268,6 +270,7 @@
 		VMImage:     "windows-buildlet",
 		machineType: "n1-highcpu-2",
 		Go14URL:     "https://storage.googleapis.com/go-builder-data/go1.4-windows-amd64.tar.gz",
+		RegularDisk: true,
 		env:         []string{"GOARCH=amd64", "GOHOSTARCH=amd64"},
 	})
 	addBuilder(BuildConfig{
@@ -275,6 +278,7 @@
 		VMImage:     "windows-buildlet",
 		machineType: "n1-highcpu-4",
 		Go14URL:     "https://storage.googleapis.com/go-builder-data/go1.4-windows-amd64.tar.gz",
+		RegularDisk: true,
 		env:         []string{"GOARCH=amd64", "GOHOSTARCH=amd64"},
 	})
 	addBuilder(BuildConfig{
@@ -283,6 +287,7 @@
 		machineType: "n1-highcpu-2",
 		buildletURL: "http://storage.googleapis.com/go-builder-data/buildlet.windows-amd64",
 		Go14URL:     "https://storage.googleapis.com/go-builder-data/go1.4-windows-386.tar.gz",
+		RegularDisk: true,
 		env:         []string{"GOARCH=386", "GOHOSTARCH=386"},
 	})
 }