diff --git a/cmd/thanos/sidecar.go b/cmd/thanos/sidecar.go
index 1e31b54d15..538f25016f 100644
--- a/cmd/thanos/sidecar.go
+++ b/cmd/thanos/sidecar.go
@@ -2,6 +2,8 @@ package main
 
 import (
 	"context"
+	"github.com/hashicorp/go-version"
+	"github.com/prometheus/common/model"
 	"math"
 	"net"
 	"net/http"
@@ -53,6 +55,8 @@ func registerSidecar(m map[string]setupFunc, app *kingpin.Application, name stri
 
 	uploadCompacted := cmd.Flag("shipper.upload-compacted", "[Experimental] If true sidecar will try to upload compacted blocks as well. Useful for migration purposes. Works only if compaction is disabled on Prometheus.").Default("false").Hidden().Bool()
 
+	validateProm := cmd.Flag("sidecar.validate-prom", "[Experimental]If true sidecar will check Prometheus' flags to ensure disabled compaction and 2h block-time.").Default("true").Hidden().Bool()
+
 	m[name] = func(g *run.Group, logger log.Logger, reg *prometheus.Registry, tracer opentracing.Tracer, _ bool) error {
 		rl := reloader.New(
 			log.With(logger, "component", "reloader"),
@@ -81,6 +85,7 @@ func registerSidecar(m map[string]setupFunc, app *kingpin.Application, name stri
 			peer,
 			rl,
 			*uploadCompacted,
+			*validateProm,
 		)
 	}
 }
@@ -101,6 +106,7 @@ func runSidecar(
 	peer cluster.Peer,
 	reloader *reloader.Reloader,
 	uploadCompacted bool,
+	validateProm bool,
 ) error {
 	var m = &promMetadata{
 		promURL: promURL,
@@ -125,6 +131,40 @@ func runSidecar(
 
 		ctx, cancel := context.WithCancel(context.Background())
 		g.Add(func() error {
+			if validateProm {
+				// Retry infinitely until we get Prometheus version.
+				err := runutil.Retry(2*time.Second, ctx.Done(), func() error {
+					err := m.FetchPromVersion(logger)
+					if err != nil {
+						level.Warn(logger).Log(
+							"msg", "failed to get Prometheus version. Is Prometheus running? Retrying",
+							"err", err,
+						)
+						return errors.Wrapf(err, "fetch Prometheus version")
+					}
+					return nil
+				})
+				if err != nil {
+					return err
+				}
+
+				if m.version == nil {
+					level.Warn(logger).Log("msg", "can't fetch version, skip validation")
+				} else {
+					// Check if Prometheus has /status/flags endpoint.
+					if m.version.LessThan(promclient.FlagsVersion) {
+						level.Warn(logger).Log("msg",
+							"Prometheus doesn't support flags endpoint, skip validation", "version", m.version.Original())
+						return nil
+					}
+
+					// Check prometheus's flags to ensure sane sidecar flags.
+					if err := validatePrometheus(ctx, logger, promURL, dataDir); err != nil {
+						return errors.Wrap(err, "validate Prometheus flags")
+					}
+				}
+			}
+
 			// Blocking query of external labels before joining as a Source Peer into gossip.
 			// We retry infinitely until we reach and fetch labels from our Prometheus.
 			err := runutil.Retry(2*time.Second, ctx.Done(), func() error {
@@ -298,13 +338,31 @@ func runSidecar(
 	return nil
 }
 
+func validatePrometheus(ctx context.Context, logger log.Logger, promURL *url.URL, tsdbPath string) error {
+	flags, err := promclient.ConfiguredFlags(ctx, logger, promURL)
+	if err != nil {
+		return errors.Wrap(err, "configured flags; failed to check flags")
+	}
+	// Check if min-block-time and max-block-time are the same.
+	if flags.TSDBMinTime != flags.TSDBMaxTime {
+		return errors.New("TSDB Min-block-time mismatches with Max-block-time")
+	}
+	// Check if block-time equals 2h.
+	if flags.TSDBMinTime != model.Duration(2*time.Hour) {
+		level.Warn(logger).Log("msg", "TSDB Max-block-time and Min-block-time should be configured to 2h", "block-time", flags.TSDBMinTime)
+	}
+
+	return nil
+}
+
 type promMetadata struct {
 	promURL *url.URL
 
-	mtx    sync.Mutex
-	mint   int64
-	maxt   int64
-	labels labels.Labels
+	mtx     sync.Mutex
+	mint    int64
+	maxt    int64
+	labels  labels.Labels
+	version *version.Version
 }
 
 func (s *promMetadata) UpdateLabels(ctx context.Context, logger log.Logger) error {
@@ -355,3 +413,8 @@ func (s *promMetadata) Timestamps() (mint int64, maxt int64) {
 
 	return s.mint, s.maxt
 }
+
+func (s *promMetadata) FetchPromVersion(logger log.Logger) (err error) {
+	s.version, err =  promclient.GetPromVersion(logger, s.promURL)
+	return err
+}
\ No newline at end of file
diff --git a/pkg/promclient/promclient.go b/pkg/promclient/promclient.go
index e70fbb245b..8b7596493f 100644
--- a/pkg/promclient/promclient.go
+++ b/pkg/promclient/promclient.go
@@ -6,6 +6,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"github.com/hashicorp/go-version"
 	"io/ioutil"
 	"net/http"
 	"net/url"
@@ -28,6 +29,12 @@ import (
 	"gopkg.in/yaml.v2"
 )
 
+var FlagsVersion *version.Version
+
+func init() {
+	FlagsVersion, _ = version.NewVersion("2.2.0")
+}
+
 // IsWALFileAccesible returns no error if WAL dir can be found. This helps to tell
 // if we have access to Prometheus TSDB directory.
 func IsWALDirAccesible(dir string) error {
@@ -335,6 +342,32 @@ func PromqlQueryInstant(ctx context.Context, logger log.Logger, base *url.URL, q
 	return vec, nil
 }
 
+// GetPromVersion will return the version of Prometheus by querying /version Prometheus endpoint.
+func GetPromVersion(logger log.Logger, base *url.URL) (*version.Version, error) {
+	if logger == nil {
+		logger = log.NewNopLogger()
+	}
+
+	u := *base
+	u.Path = path.Join(u.Path, "/version")
+	resp, err := http.Get(u.String())
+	if err != nil {
+		return nil, errors.Wrapf(err, "request version against %s", u.String())
+	}
+	defer runutil.CloseWithLogOnErr(logger, resp.Body, "query body")
+
+	b, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, errors.Errorf("failed to read body")
+	}
+
+	if resp.StatusCode != 200 {
+		return nil, errors.Errorf("got non-200 response code: %v, response: %v", resp.StatusCode, string(b))
+	}
+
+	return parseVersion(b)
+}
+
 // Scalar response consists of array with mixed types so it needs to be
 // unmarshaled separately.
 func convertScalarJSONToVector(scalarJSONResult json.RawMessage) (model.Vector, error) {
@@ -362,3 +395,24 @@ func convertScalarJSONToVector(scalarJSONResult json.RawMessage) (model.Vector,
 		Value:     resultValue,
 		Timestamp: resultTime}}, nil
 }
+
+// parseVersion converts string to version.Version.
+func parseVersion(data []byte) (*version.Version, error) {
+	var m struct {
+		Version string `json:"version"`
+	}
+	if err := json.Unmarshal(data, &m); err != nil {
+		return nil, errors.Wrapf(err, "unmarshal response: %v", string(data))
+	}
+
+	if strings.TrimSpace(m.Version) == "" {
+		return nil, nil
+	}
+
+	ver, err := version.NewVersion(m.Version)
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to parse version %s", m.Version)
+	}
+
+	return ver, nil
+}
\ No newline at end of file
diff --git a/pkg/promclient/promclient_e2e_test.go b/pkg/promclient/promclient_e2e_test.go
index 1cb7c968af..0f5bb0b0ab 100644
--- a/pkg/promclient/promclient_e2e_test.go
+++ b/pkg/promclient/promclient_e2e_test.go
@@ -3,6 +3,7 @@ package promclient
 import (
 	"context"
 	"fmt"
+	"github.com/hashicorp/go-version"
 	"io/ioutil"
 	"net/url"
 	"os"
@@ -142,3 +143,36 @@ func TestRule_UnmarshalScalarResponse(t *testing.T) {
 	vectorResult, err = convertScalarJSONToVector(invalidDataScalarJSONResult)
 	testutil.NotOk(t, err)
 }
+
+func TestParseVersion(t *testing.T) {
+	promVersions := map[string]string{
+		"": promVersionResp(""),
+		"2.2.0": promVersionResp("2.2.0"),
+		"2.3.0": promVersionResp("2.3.0"),
+		"2.3.0-rc.0": promVersionResp("2.3.0-rc.0"),
+	}
+
+	promMalformedVersions := map[string]string{
+		"foo": promVersionResp("foo"),
+		"bar": promVersionResp("bar"),
+	}
+
+	for v, resp := range promVersions {
+		gotVersion, err := parseVersion([]byte(resp))
+		testutil.Ok(t, err)
+		expectVersion, _ := version.NewVersion(v)
+		testutil.Equals(t, gotVersion, expectVersion)
+	}
+
+	for v, resp := range promMalformedVersions {
+		gotVersion, err := parseVersion([]byte(resp))
+		testutil.NotOk(t, err)
+		expectVersion, _ := version.NewVersion(v)
+		testutil.Equals(t, gotVersion, expectVersion)
+	}
+}
+
+// promVersionResp returns the response of Prometheus /version endpoint.
+func promVersionResp(ver string) string {
+	return fmt.Sprintf(`{"version":"%s","revision":"","branch":"","buildUser":"","buildDate":"","goVersion":""}`, ver)
+}
\ No newline at end of file
diff --git a/test/e2e/spinup_test.go b/test/e2e/spinup_test.go
index 592c1e7e69..0e8dbff507 100644
--- a/test/e2e/spinup_test.go
+++ b/test/e2e/spinup_test.go
@@ -78,6 +78,7 @@ func scraper(i int, config string) cmdScheduleFunc {
 		cmds = append(cmds, exec.Command(testutil.PrometheusBinary(),
 			"--config.file", promDir+"/prometheus.yml",
 			"--storage.tsdb.path", promDir,
+			"--storage.tsdb.max-block-duration", "2h",
 			"--log.level", "info",
 			"--web.listen-address", promHTTP(i),
 		))