diff --git a/vendor/github.com/fabxc/tsdb/block.go b/vendor/github.com/fabxc/tsdb/block.go
index db63e14f2..ad369a4a1 100644
--- a/vendor/github.com/fabxc/tsdb/block.go
+++ b/vendor/github.com/fabxc/tsdb/block.go
@@ -7,6 +7,7 @@ import (
 	"path/filepath"
 	"sort"
 
+	"github.com/oklog/ulid"
 	"github.com/pkg/errors"
 )
 
@@ -22,11 +23,7 @@ type Block interface {
 	Index() IndexReader
 
 	// Series returns a SeriesReader over the block's data.
-	Series() SeriesReader
-
-	// Persisted returns whether the block is already persisted,
-	// and no longer being appended to.
-	Persisted() bool
+	Chunks() ChunkReader
 
 	// Close releases all underlying resources of the block.
 	Close() error
@@ -34,6 +31,9 @@ type Block interface {
 
 // BlockMeta provides meta information about a block.
 type BlockMeta struct {
+	// Unique identifier for the block and its contents. Changes on compaction.
+	ULID ulid.ULID `json:"ulid"`
+
 	// Sequence number of the block.
 	Sequence int `json:"sequence"`
 
@@ -64,9 +64,7 @@ type persistedBlock struct {
 	dir  string
 	meta BlockMeta
 
-	chunksf, indexf *mmapFile
-
-	chunkr *seriesReader
+	chunkr *chunkReader
 	indexr *indexReader
 }
 
@@ -120,58 +118,40 @@ func newPersistedBlock(dir string) (*persistedBlock, error) {
 		return nil, err
 	}
 
-	chunksf, err := openMmapFile(chunksFileName(dir))
+	cr, err := newChunkReader(chunkDir(dir))
 	if err != nil {
-		return nil, errors.Wrap(err, "open chunk file")
+		return nil, err
 	}
-	indexf, err := openMmapFile(indexFileName(dir))
+	ir, err := newIndexReader(dir)
 	if err != nil {
-		return nil, errors.Wrap(err, "open index file")
-	}
-
-	sr, err := newSeriesReader([][]byte{chunksf.b})
-	if err != nil {
-		return nil, errors.Wrap(err, "create series reader")
-	}
-	ir, err := newIndexReader(indexf.b)
-	if err != nil {
-		return nil, errors.Wrap(err, "create index reader")
+		return nil, err
 	}
 
 	pb := &persistedBlock{
-		dir:     dir,
-		meta:    *meta,
-		chunksf: chunksf,
-		indexf:  indexf,
-		chunkr:  sr,
-		indexr:  ir,
+		dir:    dir,
+		meta:   *meta,
+		chunkr: cr,
+		indexr: ir,
 	}
 	return pb, nil
 }
 
 func (pb *persistedBlock) Close() error {
-	err0 := pb.chunksf.Close()
-	err1 := pb.indexf.Close()
+	var merr MultiError
 
-	if err0 != nil {
-		return err0
-	}
-	return err1
+	merr.Add(pb.chunkr.Close())
+	merr.Add(pb.indexr.Close())
+
+	return merr.Err()
 }
 
-func (pb *persistedBlock) Dir() string          { return pb.dir }
-func (pb *persistedBlock) Persisted() bool      { return true }
-func (pb *persistedBlock) Index() IndexReader   { return pb.indexr }
-func (pb *persistedBlock) Series() SeriesReader { return pb.chunkr }
-func (pb *persistedBlock) Meta() BlockMeta      { return pb.meta }
+func (pb *persistedBlock) Dir() string         { return pb.dir }
+func (pb *persistedBlock) Index() IndexReader  { return pb.indexr }
+func (pb *persistedBlock) Chunks() ChunkReader { return pb.chunkr }
+func (pb *persistedBlock) Meta() BlockMeta     { return pb.meta }
 
-func chunksFileName(path string) string {
-	return filepath.Join(path, "chunks-000")
-}
-
-func indexFileName(path string) string {
-	return filepath.Join(path, "index-000")
-}
+func chunkDir(dir string) string { return filepath.Join(dir, "chunks") }
+func walDir(dir string) string   { return filepath.Join(dir, "wal") }
 
 type mmapFile struct {
 	f *os.File
diff --git a/vendor/github.com/fabxc/tsdb/compact.go b/vendor/github.com/fabxc/tsdb/compact.go
index 6a0d67499..9ae18f198 100644
--- a/vendor/github.com/fabxc/tsdb/compact.go
+++ b/vendor/github.com/fabxc/tsdb/compact.go
@@ -1,12 +1,14 @@
 package tsdb
 
 import (
+	"math/rand"
 	"os"
 	"path/filepath"
 	"time"
 
 	"github.com/coreos/etcd/pkg/fileutil"
 	"github.com/fabxc/tsdb/labels"
+	"github.com/oklog/ulid"
 	"github.com/pkg/errors"
 	"github.com/prometheus/client_golang/prometheus"
 )
@@ -60,11 +62,12 @@ func newCompactor(r prometheus.Registerer, opts *compactorOptions) *compactor {
 }
 
 type compactionInfo struct {
+	seq        int
 	generation int
 	mint, maxt int64
 }
 
-const compactionBlocksLen = 4
+const compactionBlocksLen = 3
 
 // pick returns a range [i, j) in the blocks that are suitable to be compacted
 // into a single block at position i.
@@ -103,8 +106,8 @@ func (c *compactor) pick(bs []compactionInfo) (i, j int, ok bool) {
 	}
 
 	// Then we care about compacting multiple blocks, starting with the oldest.
-	for i := 0; i < len(bs)-compactionBlocksLen; i += compactionBlocksLen {
-		if c.match(bs[i : i+2]) {
+	for i := 0; i < len(bs)-compactionBlocksLen+1; i += compactionBlocksLen {
+		if c.match(bs[i : i+3]) {
 			return i, i + compactionBlocksLen, true
 		}
 	}
@@ -114,28 +117,24 @@ func (c *compactor) pick(bs []compactionInfo) (i, j int, ok bool) {
 
 func (c *compactor) match(bs []compactionInfo) bool {
 	g := bs[0].generation
-	if g >= 5 {
-		return false
-	}
 
 	for _, b := range bs {
-		if b.generation == 0 {
-			continue
-		}
 		if b.generation != g {
 			return false
 		}
 	}
-
 	return uint64(bs[len(bs)-1].maxt-bs[0].mint) <= c.opts.maxBlockRange
 }
 
+var entropy = rand.New(rand.NewSource(time.Now().UnixNano()))
+
 func mergeBlockMetas(blocks ...Block) (res BlockMeta) {
 	m0 := blocks[0].Meta()
 
 	res.Sequence = m0.Sequence
 	res.MinTime = m0.MinTime
 	res.MaxTime = blocks[len(blocks)-1].Meta().MaxTime
+	res.ULID = ulid.MustNew(ulid.Now(), entropy)
 
 	g := m0.Compaction.Generation
 	if g == 0 && len(blocks) > 1 {
@@ -166,18 +165,15 @@ func (c *compactor) compact(dir string, blocks ...Block) (err error) {
 		return err
 	}
 
-	chunkf, err := os.OpenFile(chunksFileName(dir), os.O_WRONLY|os.O_CREATE, 0666)
+	chunkw, err := newChunkWriter(chunkDir(dir))
 	if err != nil {
-		return errors.Wrap(err, "create chunk file")
+		return errors.Wrap(err, "open chunk writer")
 	}
-	indexf, err := os.OpenFile(indexFileName(dir), os.O_WRONLY|os.O_CREATE, 0666)
+	indexw, err := newIndexWriter(dir)
 	if err != nil {
-		return errors.Wrap(err, "create index file")
+		return errors.Wrap(err, "open index writer")
 	}
 
-	indexw := newIndexWriter(indexf)
-	chunkw := newChunkWriter(chunkf)
-
 	if err = c.write(dir, blocks, indexw, chunkw); err != nil {
 		return errors.Wrap(err, "write compaction")
 	}
@@ -188,18 +184,6 @@ func (c *compactor) compact(dir string, blocks ...Block) (err error) {
 	if err = indexw.Close(); err != nil {
 		return errors.Wrap(err, "close index writer")
 	}
-	if err = fileutil.Fsync(chunkf); err != nil {
-		return errors.Wrap(err, "fsync chunk file")
-	}
-	if err = fileutil.Fsync(indexf); err != nil {
-		return errors.Wrap(err, "fsync index file")
-	}
-	if err = chunkf.Close(); err != nil {
-		return errors.Wrap(err, "close chunk file")
-	}
-	if err = indexf.Close(); err != nil {
-		return errors.Wrap(err, "close index file")
-	}
 	return nil
 }
 
@@ -215,7 +199,7 @@ func (c *compactor) write(dir string, blocks []Block, indexw IndexWriter, chunkw
 		if hb, ok := b.(*headBlock); ok {
 			all = hb.remapPostings(all)
 		}
-		s := newCompactionSeriesSet(b.Index(), b.Series(), all)
+		s := newCompactionSeriesSet(b.Index(), b.Chunks(), all)
 
 		if i == 0 {
 			set = s
@@ -300,17 +284,17 @@ type compactionSet interface {
 type compactionSeriesSet struct {
 	p      Postings
 	index  IndexReader
-	series SeriesReader
+	chunks ChunkReader
 
 	l   labels.Labels
 	c   []ChunkMeta
 	err error
 }
 
-func newCompactionSeriesSet(i IndexReader, s SeriesReader, p Postings) *compactionSeriesSet {
+func newCompactionSeriesSet(i IndexReader, c ChunkReader, p Postings) *compactionSeriesSet {
 	return &compactionSeriesSet{
 		index:  i,
-		series: s,
+		chunks: c,
 		p:      p,
 	}
 }
@@ -327,7 +311,7 @@ func (c *compactionSeriesSet) Next() bool {
 	for i := range c.c {
 		chk := &c.c[i]
 
-		chk.Chunk, c.err = c.series.Chunk(chk.Ref)
+		chk.Chunk, c.err = c.chunks.Chunk(chk.Ref)
 		if c.err != nil {
 			return false
 		}
diff --git a/vendor/github.com/fabxc/tsdb/db.go b/vendor/github.com/fabxc/tsdb/db.go
index 10253ca1d..001509d5d 100644
--- a/vendor/github.com/fabxc/tsdb/db.go
+++ b/vendor/github.com/fabxc/tsdb/db.go
@@ -4,6 +4,7 @@ package tsdb
 import (
 	"bytes"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"math"
 	"os"
@@ -131,7 +132,7 @@ func newDBMetrics(r prometheus.Registerer) *dbMetrics {
 }
 
 // Open returns a new DB in the given directory.
-func Open(dir string, logger log.Logger, opts *Options) (db *DB, err error) {
+func Open(dir string, l log.Logger, r prometheus.Registerer, opts *Options) (db *DB, err error) {
 	if err := os.MkdirAll(dir, 0777); err != nil {
 		return nil, err
 	}
@@ -148,8 +149,10 @@ func Open(dir string, logger log.Logger, opts *Options) (db *DB, err error) {
 		return nil, errors.Wrapf(err, "open DB in %s", dir)
 	}
 
-	var r prometheus.Registerer
-	// r := prometheus.DefaultRegisterer
+	if l == nil {
+		l = log.NewLogfmtLogger(os.Stdout)
+		l = log.NewContext(l).With("ts", log.DefaultTimestampUTC, "caller", log.DefaultCaller)
+	}
 
 	if opts == nil {
 		opts = DefaultOptions
@@ -161,7 +164,7 @@ func Open(dir string, logger log.Logger, opts *Options) (db *DB, err error) {
 	db = &DB{
 		dir:      dir,
 		lockf:    lockf,
-		logger:   logger,
+		logger:   l,
 		metrics:  newDBMetrics(r),
 		opts:     opts,
 		compactc: make(chan struct{}, 1),
@@ -189,6 +192,7 @@ func (db *DB) run() {
 		case <-db.compactc:
 			db.metrics.compactionsTriggered.Inc()
 
+			var seqs []int
 			var infos []compactionInfo
 			for _, b := range db.compactable() {
 				m := b.Meta()
@@ -197,17 +201,16 @@ func (db *DB) run() {
 					generation: m.Compaction.Generation,
 					mint:       m.MinTime,
 					maxt:       m.MaxTime,
+					seq:        m.Sequence,
 				})
+				seqs = append(seqs, m.Sequence)
 			}
 
 			i, j, ok := db.compactor.pick(infos)
 			if !ok {
 				continue
 			}
-			db.logger.Log("msg", "picked", "i", i, "j", j)
-			for k := i; k < j; k++ {
-				db.logger.Log("k", k, "generation", infos[k].generation)
-			}
+			db.logger.Log("msg", "compact", "seqs", fmt.Sprintf("%v", seqs[i:j]))
 
 			if err := db.compact(i, j); err != nil {
 				db.logger.Log("msg", "compaction failed", "err", err)
@@ -298,11 +301,16 @@ func (db *DB) compact(i, j int) error {
 	db.persisted = append(db.persisted, pb)
 
 	for _, b := range blocks[1:] {
+		db.logger.Log("msg", "remove old dir", "dir", b.Dir())
 		if err := os.RemoveAll(b.Dir()); err != nil {
 			return errors.Wrap(err, "removing old block")
 		}
 	}
-	return db.retentionCutoff()
+	if err := db.retentionCutoff(); err != nil {
+		return err
+	}
+
+	return nil
 }
 
 func (db *DB) retentionCutoff() error {
@@ -726,7 +734,7 @@ func isPowTwo(x int) bool {
 }
 
 // OpenPartitioned or create a new DB.
-func OpenPartitioned(dir string, n int, l log.Logger, opts *Options) (*PartitionedDB, error) {
+func OpenPartitioned(dir string, n int, l log.Logger, r prometheus.Registerer, opts *Options) (*PartitionedDB, error) {
 	if !isPowTwo(n) {
 		return nil, errors.Errorf("%d is not a power of two", n)
 	}
@@ -754,7 +762,7 @@ func OpenPartitioned(dir string, n int, l log.Logger, opts *Options) (*Partition
 		l := log.NewContext(l).With("partition", i)
 		d := partitionDir(dir, i)
 
-		s, err := Open(d, l, opts)
+		s, err := Open(d, l, r, opts)
 		if err != nil {
 			return nil, fmt.Errorf("initializing partition %q failed: %s", d, err)
 		}
@@ -880,3 +888,12 @@ func yoloString(b []byte) string {
 	}
 	return *((*string)(unsafe.Pointer(&h)))
 }
+
+func closeAll(cs ...io.Closer) error {
+	var merr MultiError
+
+	for _, c := range cs {
+		merr.Add(c.Close())
+	}
+	return merr.Err()
+}
diff --git a/vendor/github.com/fabxc/tsdb/head.go b/vendor/github.com/fabxc/tsdb/head.go
index d9ab2944c..260fb962e 100644
--- a/vendor/github.com/fabxc/tsdb/head.go
+++ b/vendor/github.com/fabxc/tsdb/head.go
@@ -14,6 +14,7 @@ import (
 	"github.com/fabxc/tsdb/chunks"
 	"github.com/fabxc/tsdb/labels"
 	"github.com/go-kit/kit/log"
+	"github.com/oklog/ulid"
 	"github.com/pkg/errors"
 )
 
@@ -62,11 +63,16 @@ type headBlock struct {
 }
 
 func createHeadBlock(dir string, seq int, l log.Logger, mint, maxt int64) (*headBlock, error) {
-	if err := os.MkdirAll(dir, 0755); err != nil {
+	if err := os.MkdirAll(dir, 0777); err != nil {
+		return nil, err
+	}
+	ulid, err := ulid.New(ulid.Now(), entropy)
+	if err != nil {
 		return nil, err
 	}
 
 	if err := writeMetaFile(dir, &BlockMeta{
+		ULID:     ulid,
 		Sequence: seq,
 		MinTime:  mint,
 		MaxTime:  maxt,
@@ -133,10 +139,19 @@ func (h *headBlock) inBounds(t int64) bool {
 
 // Close syncs all data and closes underlying resources of the head block.
 func (h *headBlock) Close() error {
-	if err := writeMetaFile(h.dir, &h.meta); err != nil {
+	if err := h.wal.Close(); err != nil {
 		return err
 	}
-	return h.wal.Close()
+	// Check whether the head block still exists in the underlying dir
+	// or has already been replaced with a compacted version
+	meta, err := readMetaFile(h.dir)
+	if err != nil {
+		return err
+	}
+	if meta.ULID == h.meta.ULID {
+		return writeMetaFile(h.dir, &h.meta)
+	}
+	return nil
 }
 
 func (h *headBlock) Meta() BlockMeta {
@@ -146,10 +161,10 @@ func (h *headBlock) Meta() BlockMeta {
 	return h.meta
 }
 
-func (h *headBlock) Dir() string          { return h.dir }
-func (h *headBlock) Persisted() bool      { return false }
-func (h *headBlock) Index() IndexReader   { return &headIndexReader{h} }
-func (h *headBlock) Series() SeriesReader { return &headSeriesReader{h} }
+func (h *headBlock) Dir() string         { return h.dir }
+func (h *headBlock) Persisted() bool     { return false }
+func (h *headBlock) Index() IndexReader  { return &headIndexReader{h} }
+func (h *headBlock) Chunks() ChunkReader { return &headChunkReader{h} }
 
 func (h *headBlock) Appender() Appender {
 	atomic.AddUint64(&h.activeWriters, 1)
@@ -359,12 +374,12 @@ func (a *headAppender) Rollback() error {
 	return nil
 }
 
-type headSeriesReader struct {
+type headChunkReader struct {
 	*headBlock
 }
 
 // Chunk returns the chunk for the reference number.
-func (h *headSeriesReader) Chunk(ref uint64) (chunks.Chunk, error) {
+func (h *headChunkReader) Chunk(ref uint64) (chunks.Chunk, error) {
 	h.mtx.RLock()
 	defer h.mtx.RUnlock()
 
diff --git a/vendor/github.com/fabxc/tsdb/querier.go b/vendor/github.com/fabxc/tsdb/querier.go
index c09bab885..5f02c77f7 100644
--- a/vendor/github.com/fabxc/tsdb/querier.go
+++ b/vendor/github.com/fabxc/tsdb/querier.go
@@ -59,7 +59,7 @@ func (s *DB) Querier(mint, maxt int64) Querier {
 			mint:   mint,
 			maxt:   maxt,
 			index:  b.Index(),
-			series: b.Series(),
+			chunks: b.Chunks(),
 		}
 
 		// TODO(fabxc): find nicer solution.
@@ -123,19 +123,19 @@ func (q *querier) Close() error {
 // blockQuerier provides querying access to a single block database.
 type blockQuerier struct {
 	index  IndexReader
-	series SeriesReader
+	chunks ChunkReader
 
 	postingsMapper func(Postings) Postings
 
 	mint, maxt int64
 }
 
-func newBlockQuerier(ix IndexReader, s SeriesReader, mint, maxt int64) *blockQuerier {
+func newBlockQuerier(ix IndexReader, c ChunkReader, mint, maxt int64) *blockQuerier {
 	return &blockQuerier{
 		mint:   mint,
 		maxt:   maxt,
 		index:  ix,
-		series: s,
+		chunks: c,
 	}
 }
 
@@ -162,7 +162,7 @@ func (q *blockQuerier) Select(ms ...labels.Matcher) SeriesSet {
 
 	return &blockSeriesSet{
 		index:  q.index,
-		chunks: q.series,
+		chunks: q.chunks,
 		it:     p,
 		absent: absent,
 		mint:   q.mint,
@@ -425,7 +425,7 @@ func (s *partitionSeriesSet) Next() bool {
 // blockSeriesSet is a set of series from an inverted index query.
 type blockSeriesSet struct {
 	index      IndexReader
-	chunks     SeriesReader
+	chunks     ChunkReader
 	it         Postings // postings list referencing series
 	absent     []string // labels that must not be set for result series
 	mint, maxt int64    // considered time range
diff --git a/vendor/github.com/fabxc/tsdb/reader.go b/vendor/github.com/fabxc/tsdb/reader.go
index 630c11a99..d4d816c1f 100644
--- a/vendor/github.com/fabxc/tsdb/reader.go
+++ b/vendor/github.com/fabxc/tsdb/reader.go
@@ -3,6 +3,8 @@ package tsdb
 import (
 	"encoding/binary"
 	"fmt"
+	"io"
+	"path/filepath"
 	"strings"
 
 	"github.com/fabxc/tsdb/chunks"
@@ -10,23 +12,43 @@ import (
 	"github.com/pkg/errors"
 )
 
-// SeriesReader provides reading access of serialized time series data.
-type SeriesReader interface {
+// ChunkReader provides reading access of serialized time series data.
+type ChunkReader interface {
 	// Chunk returns the series data chunk with the given reference.
 	Chunk(ref uint64) (chunks.Chunk, error)
+
+	// Close releases all underlying resources of the reader.
+	Close() error
 }
 
-// seriesReader implements a SeriesReader for a serialized byte stream
+// chunkReader implements a SeriesReader for a serialized byte stream
 // of series data.
-type seriesReader struct {
+type chunkReader struct {
 	// The underlying bytes holding the encoded series data.
 	bs [][]byte
+
+	// Closers for resources behind the byte slices.
+	cs []io.Closer
 }
 
-func newSeriesReader(bs [][]byte) (*seriesReader, error) {
-	s := &seriesReader{bs: bs}
+// newChunkReader returns a new chunkReader based on mmaped files found in dir.
+func newChunkReader(dir string) (*chunkReader, error) {
+	files, err := sequenceFiles(dir, "")
+	if err != nil {
+		return nil, err
+	}
+	var cr chunkReader
 
-	for i, b := range bs {
+	for _, fn := range files {
+		f, err := openMmapFile(fn)
+		if err != nil {
+			return nil, errors.Wrapf(err, "mmap files")
+		}
+		cr.cs = append(cr.cs, f)
+		cr.bs = append(cr.bs, f.b)
+	}
+
+	for i, b := range cr.bs {
 		if len(b) < 4 {
 			return nil, errors.Wrapf(errInvalidSize, "validate magic in segment %d", i)
 		}
@@ -35,10 +57,14 @@ func newSeriesReader(bs [][]byte) (*seriesReader, error) {
 			return nil, fmt.Errorf("invalid magic number %x", m)
 		}
 	}
-	return s, nil
+	return &cr, nil
 }
 
-func (s *seriesReader) Chunk(ref uint64) (chunks.Chunk, error) {
+func (s *chunkReader) Close() error {
+	return closeAll(s.cs...)
+}
+
+func (s *chunkReader) Chunk(ref uint64) (chunks.Chunk, error) {
 	var (
 		seq = int(ref >> 32)
 		off = int((ref << 32) >> 32)
@@ -80,6 +106,9 @@ type IndexReader interface {
 
 	// LabelIndices returns the label pairs for which indices exist.
 	LabelIndices() ([][]string, error)
+
+	// Close released the underlying resources of the reader.
+	Close() error
 }
 
 // StringTuples provides access to a sorted list of string tuples.
@@ -94,6 +123,9 @@ type indexReader struct {
 	// The underlying byte slice holding the encoded series data.
 	b []byte
 
+	// Close that releases the underlying resources of the byte slice.
+	c io.Closer
+
 	// Cached hashmaps of section offsets.
 	labels   map[string]uint32
 	postings map[string]uint32
@@ -104,34 +136,38 @@ var (
 	errInvalidFlag = fmt.Errorf("invalid flag")
 )
 
-func newIndexReader(b []byte) (*indexReader, error) {
-	if len(b) < 4 {
-		return nil, errors.Wrap(errInvalidSize, "index header")
+// newIndexReader returns a new indexReader on the given directory.
+func newIndexReader(dir string) (*indexReader, error) {
+	f, err := openMmapFile(filepath.Join(dir, "index"))
+	if err != nil {
+		return nil, err
 	}
-	r := &indexReader{b: b}
+	r := &indexReader{b: f.b, c: f}
 
 	// Verify magic number.
-	if m := binary.BigEndian.Uint32(b[:4]); m != MagicIndex {
-		return nil, fmt.Errorf("invalid magic number %x", m)
+	if len(f.b) < 4 {
+		return nil, errors.Wrap(errInvalidSize, "index header")
+	}
+	if m := binary.BigEndian.Uint32(r.b[:4]); m != MagicIndex {
+		return nil, errors.Errorf("invalid magic number %x", m)
 	}
 
-	var err error
 	// The last two 4 bytes hold the pointers to the hashmaps.
-	loff := binary.BigEndian.Uint32(b[len(b)-8 : len(b)-4])
-	poff := binary.BigEndian.Uint32(b[len(b)-4:])
+	loff := binary.BigEndian.Uint32(r.b[len(r.b)-8 : len(r.b)-4])
+	poff := binary.BigEndian.Uint32(r.b[len(r.b)-4:])
 
-	f, b, err := r.section(loff)
+	flag, b, err := r.section(loff)
 	if err != nil {
 		return nil, errors.Wrapf(err, "label index hashmap section at %d", loff)
 	}
-	if r.labels, err = readHashmap(f, b); err != nil {
+	if r.labels, err = readHashmap(flag, b); err != nil {
 		return nil, errors.Wrap(err, "read label index hashmap")
 	}
-	f, b, err = r.section(poff)
+	flag, b, err = r.section(poff)
 	if err != nil {
 		return nil, errors.Wrapf(err, "postings hashmap section at %d", loff)
 	}
-	if r.postings, err = readHashmap(f, b); err != nil {
+	if r.postings, err = readHashmap(flag, b); err != nil {
 		return nil, errors.Wrap(err, "read postings hashmap")
 	}
 
@@ -169,6 +205,10 @@ func readHashmap(flag byte, b []byte) (map[string]uint32, error) {
 	return h, nil
 }
 
+func (r *indexReader) Close() error {
+	return r.c.Close()
+}
+
 func (r *indexReader) section(o uint32) (byte, []byte, error) {
 	b := r.b[o:]
 
diff --git a/vendor/github.com/fabxc/tsdb/writer.go b/vendor/github.com/fabxc/tsdb/writer.go
index 6b4e31deb..bafb0e8cd 100644
--- a/vendor/github.com/fabxc/tsdb/writer.go
+++ b/vendor/github.com/fabxc/tsdb/writer.go
@@ -6,10 +6,13 @@ import (
 	"hash"
 	"hash/crc32"
 	"io"
+	"os"
+	"path/filepath"
 	"sort"
 	"strings"
 
 	"github.com/bradfitz/slice"
+	"github.com/coreos/etcd/pkg/fileutil"
 	"github.com/fabxc/tsdb/chunks"
 	"github.com/fabxc/tsdb/labels"
 	"github.com/pkg/errors"
@@ -33,9 +36,6 @@ type ChunkWriter interface {
 	// is set and can be used to retrieve the chunks from the written data.
 	WriteChunks(chunks ...ChunkMeta) error
 
-	// Size returns the size of the data written so far.
-	Size() int64
-
 	// Close writes any required finalization and closes the resources
 	// associated with the underlying writer.
 	Close() error
@@ -44,20 +44,109 @@ type ChunkWriter interface {
 // chunkWriter implements the ChunkWriter interface for the standard
 // serialization format.
 type chunkWriter struct {
-	ow    io.Writer
-	w     *bufio.Writer
-	n     int64
-	c     int
-	crc32 hash.Hash
+	dirFile *os.File
+	files   []*os.File
+	wbuf    *bufio.Writer
+	n       int64
+	crc32   hash.Hash
+
+	segmentSize int64
 }
 
-func newChunkWriter(w io.Writer) *chunkWriter {
-	return &chunkWriter{
-		ow:    w,
-		w:     bufio.NewWriterSize(w, 1*1024*1024),
-		n:     0,
-		crc32: crc32.New(crc32.MakeTable(crc32.Castagnoli)),
+const (
+	defaultChunkSegmentSize = 512 * 1024 * 1024
+
+	chunksFormatV1 = 1
+	indexFormatV1  = 1
+)
+
+func newChunkWriter(dir string) (*chunkWriter, error) {
+	if err := os.MkdirAll(dir, 0777); err != nil {
+		return nil, err
 	}
+	dirFile, err := fileutil.OpenDir(dir)
+	if err != nil {
+		return nil, err
+	}
+	cw := &chunkWriter{
+		dirFile:     dirFile,
+		n:           0,
+		crc32:       crc32.New(crc32.MakeTable(crc32.Castagnoli)),
+		segmentSize: defaultChunkSegmentSize,
+	}
+	return cw, nil
+}
+
+func (w *chunkWriter) tail() *os.File {
+	if len(w.files) == 0 {
+		return nil
+	}
+	return w.files[len(w.files)-1]
+}
+
+// finalizeTail writes all pending data to the current tail file,
+// truncates its size, and closes it.
+func (w *chunkWriter) finalizeTail() error {
+	tf := w.tail()
+	if tf == nil {
+		return nil
+	}
+
+	if err := w.wbuf.Flush(); err != nil {
+		return err
+	}
+	if err := fileutil.Fsync(tf); err != nil {
+		return err
+	}
+	// As the file was pre-allocated, we truncate any superfluous zero bytes.
+	off, err := tf.Seek(0, os.SEEK_CUR)
+	if err != nil {
+		return err
+	}
+	if err := tf.Truncate(off); err != nil {
+		return err
+	}
+	return tf.Close()
+}
+
+func (w *chunkWriter) cut() error {
+	// Sync current tail to disk and close.
+	w.finalizeTail()
+
+	p, _, err := nextSequenceFile(w.dirFile.Name(), "")
+	if err != nil {
+		return err
+	}
+	f, err := os.OpenFile(p, os.O_WRONLY|os.O_CREATE, 0666)
+	if err != nil {
+		return err
+	}
+	if err = fileutil.Preallocate(f, w.segmentSize, true); err != nil {
+		return err
+	}
+	if err = w.dirFile.Sync(); err != nil {
+		return err
+	}
+
+	// Write header metadata for new file.
+
+	metab := make([]byte, 8)
+	binary.BigEndian.PutUint32(metab[:4], MagicSeries)
+	metab[4] = chunksFormatV1
+
+	if _, err := f.Write(metab); err != nil {
+		return err
+	}
+
+	w.files = append(w.files, f)
+	if w.wbuf != nil {
+		w.wbuf.Reset(f)
+	} else {
+		w.wbuf = bufio.NewWriterSize(f, 8*1024*1024)
+	}
+	w.n = 8
+
+	return nil
 }
 
 func (w *chunkWriter) write(wr io.Writer, b []byte) error {
@@ -66,44 +155,40 @@ func (w *chunkWriter) write(wr io.Writer, b []byte) error {
 	return err
 }
 
-func (w *chunkWriter) writeMeta() error {
-	b := [8]byte{}
-
-	binary.BigEndian.PutUint32(b[:4], MagicSeries)
-	b[4] = flagStd
-
-	return w.write(w.w, b[:])
-}
-
 func (w *chunkWriter) WriteChunks(chks ...ChunkMeta) error {
-	// Initialize with meta data.
-	if w.n == 0 {
-		if err := w.writeMeta(); err != nil {
+	// Calculate maximum space we need and cut a new segment in case
+	// we don't fit into the current one.
+	maxLen := int64(binary.MaxVarintLen32)
+	for _, c := range chks {
+		maxLen += binary.MaxVarintLen32 + 1
+		maxLen += int64(len(c.Chunk.Bytes()))
+	}
+	newsz := w.n + maxLen
+
+	if w.wbuf == nil || w.n > w.segmentSize || newsz > w.segmentSize && maxLen <= w.segmentSize {
+		if err := w.cut(); err != nil {
 			return err
 		}
 	}
 
+	// Write chunks sequentially and set the reference field in the ChunkMeta.
 	w.crc32.Reset()
-	wr := io.MultiWriter(w.crc32, w.w)
+	wr := io.MultiWriter(w.crc32, w.wbuf)
 
-	// For normal reads we don't need the number of the chunk section but
-	// it allows us to verify checksums without reading the index file.
-	// The offsets are also technically enough to calculate chunk size. but
-	// holding the length of each chunk could later allow for adding padding
-	// between chunks.
-	b := [binary.MaxVarintLen32]byte{}
-	n := binary.PutUvarint(b[:], uint64(len(chks)))
+	b := make([]byte, binary.MaxVarintLen32)
+	n := binary.PutUvarint(b, uint64(len(chks)))
 
 	if err := w.write(wr, b[:n]); err != nil {
 		return err
 	}
+	seq := uint64(w.seq()) << 32
 
 	for i := range chks {
 		chk := &chks[i]
 
-		chk.Ref = uint64(w.n)
+		chk.Ref = seq | uint64(w.n)
 
-		n = binary.PutUvarint(b[:], uint64(len(chk.Chunk.Bytes())))
+		n = binary.PutUvarint(b, uint64(len(chk.Chunk.Bytes())))
 
 		if err := w.write(wr, b[:n]); err != nil {
 			return err
@@ -117,24 +202,18 @@ func (w *chunkWriter) WriteChunks(chks ...ChunkMeta) error {
 		chk.Chunk = nil
 	}
 
-	if err := w.write(w.w, w.crc32.Sum(nil)); err != nil {
+	if err := w.write(w.wbuf, w.crc32.Sum(nil)); err != nil {
 		return err
 	}
 	return nil
 }
 
-func (w *chunkWriter) Size() int64 {
-	return w.n
+func (w *chunkWriter) seq() int {
+	return len(w.files) - 1
 }
 
 func (w *chunkWriter) Close() error {
-	// Initialize block in case no data was written to it.
-	if w.n == 0 {
-		if err := w.writeMeta(); err != nil {
-			return err
-		}
-	}
-	return w.w.Flush()
+	return w.finalizeTail()
 }
 
 // ChunkMeta holds information about a chunk of data.
@@ -155,7 +234,7 @@ type IndexWriter interface {
 	// of chunks that the index can reference.
 	// The reference number is used to resolve a series against the postings
 	// list iterator. It only has to be available during the write processing.
-	AddSeries(ref uint32, l labels.Labels, chunks ...ChunkMeta)
+	AddSeries(ref uint32, l labels.Labels, chunks ...ChunkMeta) error
 
 	// WriteLabelIndex serializes an index from label names to values.
 	// The passed in values chained tuples of strings of the length of names.
@@ -164,9 +243,6 @@ type IndexWriter interface {
 	// WritePostings writes a postings list for a single label pair.
 	WritePostings(name, value string, it Postings) error
 
-	// Size returns the size of the data written so far.
-	Size() int64
-
 	// Close writes any finalization and closes theresources associated with
 	// the underlying writer.
 	Close() error
@@ -181,13 +257,12 @@ type indexWriterSeries struct {
 // indexWriter implements the IndexWriter interface for the standard
 // serialization format.
 type indexWriter struct {
-	ow      io.Writer
-	w       *bufio.Writer
+	f       *os.File
+	bufw    *bufio.Writer
 	n       int64
 	started bool
 
-	series map[uint32]*indexWriterSeries
-
+	series       map[uint32]*indexWriterSeries
 	symbols      map[string]uint32 // symbol offsets
 	labelIndexes []hashEntry       // label index offsets
 	postings     []hashEntry       // postings lists offsets
@@ -195,15 +270,31 @@ type indexWriter struct {
 	crc32 hash.Hash
 }
 
-func newIndexWriter(w io.Writer) *indexWriter {
-	return &indexWriter{
-		w:       bufio.NewWriterSize(w, 1*1024*1024),
-		ow:      w,
+func newIndexWriter(dir string) (*indexWriter, error) {
+	df, err := fileutil.OpenDir(dir)
+	if err != nil {
+		return nil, err
+	}
+	f, err := os.OpenFile(filepath.Join(dir, "index"), os.O_CREATE|os.O_WRONLY, 0666)
+	if err != nil {
+		return nil, err
+	}
+	if err := fileutil.Fsync(df); err != nil {
+		return nil, errors.Wrap(err, "sync dir")
+	}
+
+	iw := &indexWriter{
+		f:       f,
+		bufw:    bufio.NewWriterSize(f, 1*1024*1024),
 		n:       0,
 		symbols: make(map[string]uint32, 4096),
 		series:  make(map[uint32]*indexWriterSeries, 4096),
 		crc32:   crc32.New(crc32.MakeTable(crc32.Castagnoli)),
 	}
+	if err := iw.writeMeta(); err != nil {
+		return nil, err
+	}
+	return iw, nil
 }
 
 func (w *indexWriter) write(wr io.Writer, b []byte) error {
@@ -215,7 +306,7 @@ func (w *indexWriter) write(wr io.Writer, b []byte) error {
 // section writes a CRC32 checksummed section of length l and guarded by flag.
 func (w *indexWriter) section(l uint32, flag byte, f func(w io.Writer) error) error {
 	w.crc32.Reset()
-	wr := io.MultiWriter(w.crc32, w.w)
+	wr := io.MultiWriter(w.crc32, w.bufw)
 
 	b := [5]byte{flag, 0, 0, 0, 0}
 	binary.BigEndian.PutUint32(b[1:], l)
@@ -225,9 +316,9 @@ func (w *indexWriter) section(l uint32, flag byte, f func(w io.Writer) error) er
 	}
 
 	if err := f(wr); err != nil {
-		return errors.Wrap(err, "contents write func")
+		return errors.Wrap(err, "write contents")
 	}
-	if err := w.write(w.w, w.crc32.Sum(nil)); err != nil {
+	if err := w.write(w.bufw, w.crc32.Sum(nil)); err != nil {
 		return errors.Wrap(err, "writing checksum")
 	}
 	return nil
@@ -239,10 +330,13 @@ func (w *indexWriter) writeMeta() error {
 	binary.BigEndian.PutUint32(b[:4], MagicIndex)
 	b[4] = flagStd
 
-	return w.write(w.w, b[:])
+	return w.write(w.bufw, b[:])
 }
 
-func (w *indexWriter) AddSeries(ref uint32, lset labels.Labels, chunks ...ChunkMeta) {
+func (w *indexWriter) AddSeries(ref uint32, lset labels.Labels, chunks ...ChunkMeta) error {
+	if _, ok := w.series[ref]; ok {
+		return errors.Errorf("series with reference %d already added", ref)
+	}
 	// Populate the symbol table from all label sets we have to reference.
 	for _, l := range lset {
 		w.symbols[l.Name] = 0
@@ -253,6 +347,7 @@ func (w *indexWriter) AddSeries(ref uint32, lset labels.Labels, chunks ...ChunkM
 		labels: lset,
 		chunks: chunks,
 	}
+	return nil
 }
 
 func (w *indexWriter) writeSymbols() error {
@@ -340,9 +435,6 @@ func (w *indexWriter) writeSeries() error {
 }
 
 func (w *indexWriter) init() error {
-	if err := w.writeMeta(); err != nil {
-		return err
-	}
 	if err := w.writeSymbols(); err != nil {
 		return err
 	}
@@ -439,10 +531,6 @@ func (w *indexWriter) WritePostings(name, value string, it Postings) error {
 	})
 }
 
-func (w *indexWriter) Size() int64 {
-	return w.n
-}
-
 type hashEntry struct {
 	name   string
 	offset uint32
@@ -482,24 +570,22 @@ func (w *indexWriter) finalize() error {
 	// for any index query.
 	// TODO(fabxc): also store offset to series section to allow plain
 	// iteration over all existing series?
-	// TODO(fabxc): store references like these that are not resolved via direct
-	// mmap using explicit endianness?
 	b := [8]byte{}
 	binary.BigEndian.PutUint32(b[:4], lo)
 	binary.BigEndian.PutUint32(b[4:], po)
 
-	return w.write(w.w, b[:])
+	return w.write(w.bufw, b[:])
 }
 
 func (w *indexWriter) Close() error {
-	// Handle blocks without any data.
-	if !w.started {
-		if err := w.init(); err != nil {
-			return err
-		}
-	}
 	if err := w.finalize(); err != nil {
 		return err
 	}
-	return w.w.Flush()
+	if err := w.bufw.Flush(); err != nil {
+		return err
+	}
+	if err := fileutil.Fsync(w.f); err != nil {
+		return err
+	}
+	return w.f.Close()
 }
diff --git a/vendor/vendor.json b/vendor/vendor.json
index 6df803d5e..2586d9857 100644
--- a/vendor/vendor.json
+++ b/vendor/vendor.json
@@ -368,10 +368,10 @@
 			"revisionTime": "2016-09-30T00:14:02Z"
 		},
 		{
-			"checksumSHA1": "edB8coiX4s6hf6BZuYE5+MPJYX8=",
+			"checksumSHA1": "UeErAjCWDt1vzaXGQGxnenFUg7w=",
 			"path": "github.com/fabxc/tsdb",
-			"revision": "f734773214e1bcb7962d92155863110d01214db5",
-			"revisionTime": "2017-02-19T12:01:19Z"
+			"revision": "db5c88ea9ac9400b0e58ef18b9b272c34b98639b",
+			"revisionTime": "2017-02-28T07:40:51Z"
 		},
 		{
 			"checksumSHA1": "uVzWuLvF646YjiKomsc2CR1ua58=",