diff --git a/block.go b/block.go
index 8e9d0c2e7..41dc640e4 100644
--- a/block.go
+++ b/block.go
@@ -68,9 +68,9 @@ type persistedBlock struct {
 }
 
 type blockMeta struct {
-	*BlockMeta
-
 	Version int `json:"version"`
+
+	*BlockMeta
 }
 
 const metaFilename = "meta.json"
diff --git a/compact.go b/compact.go
index 9267dd5ef..20c46aaa8 100644
--- a/compact.go
+++ b/compact.go
@@ -49,7 +49,6 @@ func newCompactorMetrics(r prometheus.Registerer) *compactorMetrics {
 }
 
 type compactorOptions struct {
-	maxBlocks     uint8
 	maxBlockRange uint64
 	maxSize       uint64
 }
@@ -61,9 +60,14 @@ func newCompactor(r prometheus.Registerer, opts *compactorOptions) *compactor {
 	}
 }
 
+type compactionInfo struct {
+	generation int
+	mint, maxt int64
+}
+
 // pick returns a range [i, j] in the blocks that are suitable to be compacted
 // into a single block at position i.
-func (c *compactor) pick(bs []Block) (i, j int, ok bool) {
+func (c *compactor) pick(bs []compactionInfo) (i, j int, ok bool) {
 
 	last := len(bs) - 1
 	if len(bs) == 0 {
@@ -71,8 +75,8 @@ func (c *compactor) pick(bs []Block) (i, j int, ok bool) {
 	}
 
 	// Make sure we always compact the last block if unpersisted.
-	if bs[last].Meta().Compaction.Generation == 0 {
-		if len(bs) >= 3 && compactionMatch(bs[last-2:last+1]) {
+	if bs[last].generation == 0 {
+		if len(bs) >= 3 && c.match(bs[last-2:last+1]) {
 			return last - 2, last, true
 		}
 		return last, last, true
@@ -80,55 +84,40 @@ func (c *compactor) pick(bs []Block) (i, j int, ok bool) {
 
 	for i := len(bs); i-3 >= 0; i -= 3 {
 		tpl := bs[i-3 : i]
-		if compactionMatch(tpl) {
+		if c.match(tpl) {
 			return i - 3, i - 1, true
 		}
 	}
 	return 0, 0, false
 }
 
-func compactionMatch(blocks []Block) bool {
-	g := blocks[0].Meta().Compaction.Generation
+func (c *compactor) match(bs []compactionInfo) bool {
+	g := bs[0].generation
 	if g >= 5 {
 		return false
 	}
 
-	for _, b := range blocks[1:] {
-		if b.Meta().Compaction.Generation == 0 {
+	for _, b := range bs {
+		if b.generation == 0 {
 			continue
 		}
-		if b.Meta().Compaction.Generation != g {
+		if b.generation != g {
 			return false
 		}
 	}
-	return true
 
-	// TODO(fabxc): check whether combined size is below maxCompactionSize.
-	// Apply maximum time range? or number of series? – might already be covered by size implicitly.
-
-	// Naively check whether both blocks have roughly the same number of samples
-	// and whether the total sample count doesn't exceed 2GB chunk file size
-	// by rough approximation.
-	n := float64(blocks[0].Meta().Stats.NumSamples)
-	t := n
-
-	for _, b := range blocks[1:] {
-		m := float64(b.Meta().Stats.NumSamples)
-
-		if m < 0.7*n || m > 1.3*n {
-			return false
-		}
-		t += m
-	}
-
-	// Pessimistic 10 bytes/sample should do.
-	return t < 10*200e6
+	return uint64(bs[len(bs)-1].maxt-bs[0].mint) <= c.opts.maxBlockRange
 }
 
 func mergeBlockMetas(blocks ...Block) (res BlockMeta) {
 	res.MinTime = blocks[0].Meta().MinTime
 	res.MaxTime = blocks[len(blocks)-1].Meta().MaxTime
-	res.Compaction.Generation = blocks[0].Meta().Compaction.Generation + 1
+
+	g := blocks[0].Meta().Compaction.Generation
+	if g == 0 && len(blocks) > 1 {
+		g++
+	}
+	res.Compaction.Generation = g + 1
 
 	for _, b := range blocks {
 		res.Stats.NumSamples += b.Meta().Stats.NumSamples
diff --git a/db.go b/db.go
index 99aa16810..0e869f0eb 100644
--- a/db.go
+++ b/db.go
@@ -132,7 +132,6 @@ func Open(dir string, logger log.Logger, opts *Options) (db *DB, err error) {
 	}
 	db.compactor = newCompactor(r, &compactorOptions{
 		maxBlockRange: opts.MaxBlockRange,
-		maxBlocks:     3,
 		maxSize:       1 << 29, // 512MB
 	})
 
@@ -148,31 +147,49 @@ func Open(dir string, logger log.Logger, opts *Options) (db *DB, err error) {
 func (db *DB) run() {
 	defer close(db.donec)
 
-	for {
-		select {
-		case <-db.cutc:
-			db.mtx.Lock()
-			_, err := db.cut()
-			db.mtx.Unlock()
-
-			if err != nil {
-				db.logger.Log("msg", "cut failed", "err", err)
-			} else {
-				select {
-				case db.compactc <- struct{}{}:
-				default:
-				}
-			}
-			// Drain cut channel so we don't trigger immediately again.
+	go func() {
+		for {
 			select {
 			case <-db.cutc:
-			default:
-			}
+				db.mtx.Lock()
+				_, err := db.cut()
+				db.mtx.Unlock()
 
+				if err != nil {
+					db.logger.Log("msg", "cut failed", "err", err)
+				} else {
+					select {
+					case db.compactc <- struct{}{}:
+					default:
+					}
+				}
+				// Drain cut channel so we don't trigger immediately again.
+				select {
+				case <-db.cutc:
+				default:
+				}
+			case <-db.stopc:
+			}
+		}
+	}()
+
+	for {
+		select {
 		case <-db.compactc:
 			db.metrics.compactionsTriggered.Inc()
 
-			i, j, ok := db.compactor.pick(db.compactable())
+			var infos []compactionInfo
+			for _, b := range db.compactable() {
+				m := b.Meta()
+
+				infos = append(infos, compactionInfo{
+					generation: m.Compaction.Generation,
+					mint:       *m.MinTime,
+					maxt:       *m.MaxTime,
+				})
+			}
+
+			i, j, ok := db.compactor.pick(infos)
 			if !ok {
 				continue
 			}
@@ -180,6 +197,7 @@ func (db *DB) run() {
 				db.logger.Log("msg", "compaction failed", "err", err)
 				continue
 			}
+			db.logger.Log("msg", "compaction completed")
 			// Trigger another compaction in case there's more work to do.
 			select {
 			case db.compactc <- struct{}{}:
diff --git a/writer.go b/writer.go
index 5f250b02e..886e518bd 100644
--- a/writer.go
+++ b/writer.go
@@ -1,6 +1,7 @@
 package tsdb
 
 import (
+	"bufio"
 	"encoding/binary"
 	"hash/crc32"
 	"io"
@@ -8,7 +9,6 @@ import (
 	"strings"
 
 	"github.com/bradfitz/slice"
-	"github.com/coreos/etcd/pkg/ioutil"
 	"github.com/fabxc/tsdb/chunks"
 	"github.com/fabxc/tsdb/labels"
 	"github.com/pkg/errors"
@@ -43,7 +43,7 @@ type SeriesWriter interface {
 // serialization format.
 type seriesWriter struct {
 	ow io.Writer
-	w  *ioutil.PageWriter
+	w  *bufio.Writer
 	n  int64
 	c  int
 
@@ -53,7 +53,7 @@ type seriesWriter struct {
 func newSeriesWriter(w io.Writer, index IndexWriter) *seriesWriter {
 	return &seriesWriter{
 		ow:    w,
-		w:     ioutil.NewPageWriter(w, compactionPageBytes, 0),
+		w:     bufio.NewWriterSize(w, 1*1024*1024),
 		n:     0,
 		index: index,
 	}
@@ -180,7 +180,7 @@ type indexWriterSeries struct {
 // serialization format.
 type indexWriter struct {
 	ow      io.Writer
-	w       *ioutil.PageWriter
+	w       *bufio.Writer
 	n       int64
 	started bool
 
@@ -193,7 +193,7 @@ type indexWriter struct {
 
 func newIndexWriter(w io.Writer) *indexWriter {
 	return &indexWriter{
-		w:       ioutil.NewPageWriter(w, compactionPageBytes, 0),
+		w:       bufio.NewWriterSize(w, 1*1024*1024),
 		ow:      w,
 		n:       0,
 		symbols: make(map[string]uint32, 4096),