diff --git a/services/mounttable/btmtd/README.md b/services/mounttable/btmtd/README.md
index d08ce9a..8de7315 100644
--- a/services/mounttable/btmtd/README.md
+++ b/services/mounttable/btmtd/README.md
@@ -21,7 +21,8 @@
    * Metadata `m`: used to store information about the row:
       * Version `v`: The version changes every time the row is mutated. It is
         used to detect conflicts related to concurrent access.
-      * Timestamp `t`: The cell's timestamp is the node creation time.
+      * Creator `c`: The cell's value is the name of its creator and its
+        timestamp is the node creation time.
       * Sticky `s`: When this column is present, the node is not automatically
         garbage collected.
       * Permissions `p`: The [access.Permissions] of the node.
@@ -33,11 +34,11 @@
 
 Example:
 
-| Key              | Version | Timestamp | Sticky | Permissions  | Mounted Server...           | Child...  |
-| ---              | ---     | ---       | ---    | ---          | ---                         | ---       |
-| 540f1a56/        | 54321   | (ts)      | 1      | {"Admin":... |                             | foo (ts1) |
-| 1234abcd/foo     | 123     | (ts1)     |        | {"Admin":... |                             | bar (ts2) |
-| 46d523e3/foo/bar | 5436    | (ts2)     |        | {"Admin":... | /example.com:123 (deadline) |           |
+| Key              | Version | Creator    | Sticky | Permissions  | Mounted Server...           | Child...  |
+| ---              | ---     | ---        | ---    | ---          | ---                         | ---       |
+| 540f1a56/        | 54321   | user (ts)  | 1      | {"Admin":... |                             | foo (ts1) |
+| 1234abcd/foo     | 123     | user (ts1) |        | {"Admin":... |                             | bar (ts2) |
+| 46d523e3/foo/bar | 5436    | user (ts2) |        | {"Admin":... | /example.com:123 (deadline) |           |
 
 ## Mutations
 
diff --git a/services/mounttable/btmtd/internal/bt.go b/services/mounttable/btmtd/internal/bt.go
index 140a7a1..de89f98 100644
--- a/services/mounttable/btmtd/internal/bt.go
+++ b/services/mounttable/btmtd/internal/bt.go
@@ -5,6 +5,8 @@
 package internal
 
 import (
+	"bytes"
+	"encoding/binary"
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
@@ -23,6 +25,7 @@
 	"google.golang.org/grpc/codes"
 
 	"v.io/v23/context"
+	"v.io/v23/conventions"
 	"v.io/v23/security"
 	"v.io/v23/security/access"
 	v23mt "v.io/v23/services/mounttable"
@@ -35,10 +38,10 @@
 	serversFamily  = "s"
 	childrenFamily = "c"
 
-	versionColumn     = "v"
+	creatorColumn     = "c"
 	permissionsColumn = "p"
 	stickyColumn      = "s"
-	timestampColumn   = "t"
+	versionColumn     = "v"
 )
 
 // NewBigTable returns a BigTable object that abstracts some aspects of the
@@ -54,15 +57,17 @@
 		return nil, err
 	}
 
-	return &BigTable{
+	bt := &BigTable{
 		tableName: tableName,
 		cache:     &rowCache{},
-		tbl:       client.Open(tableName),
 		createAdminClient: func() (*bigtable.AdminClient, error) {
 			return bigtable.NewAdminClient(ctx, project, zone, cluster, cloud.WithTokenSource(tk))
 
 		},
-	}, nil
+	}
+	bt.nodeTbl = client.Open(bt.nodeTableName())
+	bt.counterTbl = client.Open(bt.counterTableName())
+	return bt, nil
 }
 
 // NewTestBigTable returns a BigTable object that is connected to an in-memory
@@ -82,11 +87,10 @@
 		return nil, nil, err
 	}
 
-	return &BigTable{
+	bt := &BigTable{
 		tableName: tableName,
 		testMode:  true,
 		cache:     &rowCache{},
-		tbl:       client.Open(tableName),
 		createAdminClient: func() (*bigtable.AdminClient, error) {
 			conn, err := grpc.Dial(srv.Addr, grpc.WithInsecure())
 			if err != nil {
@@ -94,17 +98,29 @@
 			}
 			return bigtable.NewAdminClient(ctx, "", "", "", cloud.WithBaseGRPC(conn))
 		},
-	}, func() { srv.Close() }, nil
+	}
+	bt.nodeTbl = client.Open(bt.nodeTableName())
+	bt.counterTbl = client.Open(bt.counterTableName())
+	return bt, func() { srv.Close() }, nil
 }
 
 type BigTable struct {
 	tableName         string
 	testMode          bool
-	tbl               *bigtable.Table
+	nodeTbl           *bigtable.Table
+	counterTbl        *bigtable.Table
 	cache             *rowCache
 	createAdminClient func() (*bigtable.AdminClient, error)
 }
 
+func (b *BigTable) nodeTableName() string {
+	return b.tableName
+}
+
+func (b *BigTable) counterTableName() string {
+	return b.tableName + "-counters"
+}
+
 // SetupTable creates the table, column families, and GC policies.
 func (b *BigTable) SetupTable(ctx *context.T, permissionsFile string) error {
 	bctx, cancel := btctx(ctx)
@@ -116,23 +132,28 @@
 	}
 	defer client.Close()
 
-	if err := client.CreateTable(bctx, b.tableName); err != nil {
+	if err := client.CreateTable(bctx, b.counterTableName()); err != nil {
+		return err
+	}
+	if err := client.CreateTable(bctx, b.nodeTableName()); err != nil {
 		return err
 	}
 
 	families := []struct {
-		name     string
-		gcPolicy bigtable.GCPolicy
+		tableName  string
+		familyName string
+		gcPolicy   bigtable.GCPolicy
 	}{
-		{serversFamily, bigtable.UnionPolicy(bigtable.MaxVersionsPolicy(1), bigtable.MaxAgePolicy(time.Second))},
-		{metadataFamily, bigtable.MaxVersionsPolicy(1)},
-		{childrenFamily, bigtable.MaxVersionsPolicy(1)},
+		{b.counterTableName(), metadataFamily, bigtable.MaxVersionsPolicy(1)},
+		{b.nodeTableName(), metadataFamily, bigtable.MaxVersionsPolicy(1)},
+		{b.nodeTableName(), serversFamily, bigtable.UnionPolicy(bigtable.MaxVersionsPolicy(1), bigtable.MaxAgePolicy(time.Second))},
+		{b.nodeTableName(), childrenFamily, bigtable.MaxVersionsPolicy(1)},
 	}
 	for _, f := range families {
-		if err := client.CreateColumnFamily(bctx, b.tableName, f.name); err != nil {
+		if err := client.CreateColumnFamily(bctx, f.tableName, f.familyName); err != nil {
 			return err
 		}
-		if err := client.SetGCPolicy(bctx, b.tableName, f.name, f.gcPolicy); err != nil {
+		if err := client.SetGCPolicy(bctx, f.tableName, f.familyName, f.gcPolicy); err != nil {
 			return err
 		}
 	}
@@ -142,7 +163,7 @@
 	}
 	perms := make(access.Permissions)
 	perms.Add(security.AllPrincipals, string(v23mt.Admin))
-	return b.createRow(ctx, "", perms, b.now())
+	return b.createRow(ctx, "", perms, "", b.now())
 }
 
 func (b *BigTable) timeFloor(t bigtable.Timestamp) bigtable.Timestamp {
@@ -176,7 +197,10 @@
 		return err
 	}
 	defer client.Close()
-	return client.DeleteTable(bctx, b.tableName)
+	if err := client.DeleteTable(bctx, b.counterTableName()); err != nil {
+		return err
+	}
+	return client.DeleteTable(bctx, b.nodeTableName())
 }
 
 // DumpTable prints all the mounttable nodes stored in the bigtable.
@@ -185,7 +209,7 @@
 	defer cancel()
 
 	clock := timekeeper.RealTime()
-	return b.tbl.ReadRows(bctx, bigtable.InfiniteRange(""),
+	return b.nodeTbl.ReadRows(bctx, bigtable.InfiniteRange(""),
 		func(row bigtable.Row) bool {
 			n := nodeFromRow(ctx, b, row, clock)
 			if n.name == "" {
@@ -219,7 +243,7 @@
 	defer cancel()
 
 	count := 0
-	if err := b.tbl.ReadRows(bctx, bigtable.InfiniteRange(""),
+	if err := b.nodeTbl.ReadRows(bctx, bigtable.InfiniteRange(""),
 		func(row bigtable.Row) bool {
 			count++
 			return true
@@ -265,7 +289,7 @@
 	// server.
 	// Either way, we can't used the cached version anymore.
 	defer b.cache.invalidate(row)
-	return b.tbl.Apply(bctx, row, m, opts...)
+	return b.nodeTbl.Apply(bctx, row, m, opts...)
 }
 
 func (b *BigTable) readRow(ctx *context.T, key string, opts ...bigtable.ReadOption) (bigtable.Row, error) {
@@ -273,7 +297,7 @@
 		func() (bigtable.Row, error) {
 			bctx, cancel := btctx(ctx)
 			defer cancel()
-			return b.tbl.ReadRow(bctx, key, opts...)
+			return b.nodeTbl.ReadRow(bctx, key, opts...)
 		},
 	)
 	if grpc.Code(err) == codes.DeadlineExceeded {
@@ -285,14 +309,42 @@
 	return row, err
 }
 
-func (b *BigTable) createRow(ctx *context.T, name string, perms access.Permissions, ts bigtable.Timestamp) error {
+func (b *BigTable) createRow(ctx *context.T, name string, perms access.Permissions, creator string, ts bigtable.Timestamp) error {
 	jsonPerms, err := json.Marshal(perms)
 	if err != nil {
 		return err
 	}
+	if creator == "" {
+		creator = conventions.ServerUser
+	}
 	mut := bigtable.NewMutation()
-	mut.Set(metadataFamily, timestampColumn, ts, []byte{1})
+	mut.Set(metadataFamily, creatorColumn, ts, []byte(creator))
 	mut.Set(metadataFamily, permissionsColumn, bigtable.ServerTime, jsonPerms)
 	mut.Set(metadataFamily, versionColumn, bigtable.ServerTime, []byte(strconv.FormatUint(uint64(rand.Uint32()), 10)))
-	return b.apply(ctx, rowKey(name), mut)
+	if err := b.apply(ctx, rowKey(name), mut); err != nil {
+		return err
+	}
+	return b.incrementCreatorNodeCount(ctx, creator, 1)
+}
+
+func (b *BigTable) incrementCreatorNodeCount(ctx *context.T, creator string, delta int64) error {
+	bctx, cancel := btctx(ctx)
+	defer cancel()
+
+	key := "num-nodes-per-user:" + creator
+	m := bigtable.NewReadModifyWrite()
+	m.Increment(metadataFamily, "c", delta)
+	row, err := b.counterTbl.ApplyReadModifyWrite(bctx, key, m)
+	if err != nil {
+		return err
+	}
+	if len(row[metadataFamily]) == 1 {
+		var c int64
+		b := row[metadataFamily][0].Value
+		if err := binary.Read(bytes.NewReader(b), binary.BigEndian, &c); err != nil {
+			return err
+		}
+		ctx.Infof("Counter %s = %d", key, c)
+	}
+	return nil
 }
diff --git a/services/mounttable/btmtd/internal/mounttable.go b/services/mounttable/btmtd/internal/mounttable.go
index c744974..1100ebe 100644
--- a/services/mounttable/btmtd/internal/mounttable.go
+++ b/services/mounttable/btmtd/internal/mounttable.go
@@ -13,6 +13,7 @@
 	"time"
 
 	"v.io/v23/context"
+	"v.io/v23/conventions"
 	"v.io/v23/glob"
 	"v.io/v23/naming"
 	"v.io/v23/rpc"
@@ -359,7 +360,7 @@
 				}
 			}
 			perms.Normalize()
-			n, err = parent.createChild(ctx, elem, perms)
+			n, err = parent.createChild(ctx, elem, perms, pickCreator(ctx, call))
 			if err != nil {
 				return nil, "", err
 			}
@@ -423,3 +424,7 @@
 	}
 	return templatePerms
 }
+
+func pickCreator(ctx *context.T, call security.Call) string {
+	return conventions.GetClientUserIds(ctx, call)[0]
+}
diff --git a/services/mounttable/btmtd/internal/node.go b/services/mounttable/btmtd/internal/node.go
index d26aa3a..f07fd9e 100644
--- a/services/mounttable/btmtd/internal/node.go
+++ b/services/mounttable/btmtd/internal/node.go
@@ -34,6 +34,7 @@
 	creationTime bigtable.Timestamp
 	permissions  access.Permissions
 	version      string
+	creator      string
 	mountFlags   mtFlags
 	servers      []naming.MountedServer
 	children     []string
@@ -89,8 +90,9 @@
 				ctx.Errorf("Failed to decode permissions for %s", name)
 				return nil
 			}
-		case timestampColumn:
+		case creatorColumn:
 			n.creationTime = i.Timestamp
+			n.creator = string(i.Value)
 		}
 	}
 	n.servers = make([]naming.MountedServer, 0, len(row[serversFamily]))
@@ -116,7 +118,7 @@
 	return n
 }
 
-func (n *mtNode) createChild(ctx *context.T, child string, perms access.Permissions) (*mtNode, error) {
+func (n *mtNode) createChild(ctx *context.T, child string, perms access.Permissions, creator string) (*mtNode, error) {
 	ts := n.bt.now()
 	mut := bigtable.NewMutation()
 	mut.Set(childrenFamily, child, ts, []byte{1})
@@ -134,7 +136,7 @@
 	childName := naming.Join(n.name, child)
 	longCtx, cancel := longTimeout(ctx)
 	defer cancel()
-	if err := n.bt.createRow(longCtx, childName, perms, ts); err != nil {
+	if err := n.bt.createRow(longCtx, childName, perms, creator, ts); err != nil {
 		return nil, err
 	}
 	n, err := getNode(ctx, n.bt, childName)
@@ -241,7 +243,7 @@
 			// exist. It could be that it is being created or
 			// deleted concurrently. To be sure, we have to create
 			// it before deleting it.
-			if cn, err = n.createChild(ctx, c, n.permissions); err != nil {
+			if cn, err = n.createChild(ctx, c, n.permissions, ""); err != nil {
 				return err
 			}
 		}
@@ -273,7 +275,10 @@
 
 	longCtx, cancel := longTimeout(ctx)
 	defer cancel()
-	return n.bt.apply(longCtx, rowKey(parent), mut)
+	if err := n.bt.apply(longCtx, rowKey(parent), mut); err != nil {
+		return err
+	}
+	return n.bt.incrementCreatorNodeCount(ctx, n.creator, -1)
 }
 
 func (n *mtNode) setPermissions(ctx *context.T, perms access.Permissions) error {
@@ -359,7 +364,7 @@
 	for _, node := range sortedNodes {
 		perms := nodes[node]
 		if node == "" {
-			if err := bt.createRow(ctx, "", perms, ts); err != nil {
+			if err := bt.createRow(ctx, "", perms, "", ts); err != nil {
 				return err
 			}
 			continue
@@ -375,7 +380,7 @@
 				if err != nil {
 					return err
 				}
-				if n, err = parent.createChild(ctx, e, parent.permissions); err != nil {
+				if n, err = parent.createChild(ctx, e, parent.permissions, ""); err != nil {
 					return err
 				}
 			}