*: remove migration related stuff from 2.2

Documentation/backward_compatibility.md

@@ -24,49 +24,6 @@ https://github.com/coreos/etcd/blob/master/Documentation/configuration.md.
 
 The default data dir location has changed from {$hostname}.etcd to {name}.etcd.
 
-## Data Directory Migration
-
-The disk format within the data directory changed with etcd 2.0.
-If you run etcd 2.0 on an etcd 0.4 data directory it will automatically migrate the data and start.
-You will want to coordinate this upgrade by walking through each of your machines in the cluster, stopping etcd 0.4 and then starting etcd 2.0.
-If you would rather manually do the migration, to test it out first in another environment, you can use the [migration tool doc][migrationtooldoc].
-
-[migrationtooldoc]: https://github.com/coreos/etcd/blob/master/tools/etcd-migrate/README.md
-
-## Snapshot Migration
-
-If you are only interested in the data in etcd you can migrate a snapshot of your data from a v0.4.9+ cluster into a new etcd 2.0 cluster using a snapshot migration.
-The advantage of this method is that you are directly dumping only the etcd data so you can run your old and new cluster side-by-side, snapshot the data, import it and then point your applications at this cluster.
-The disadvantage is that the etcd indexes of your data will change which may confuse applications that use etcd.
-
-To get started get the newest data snapshot from the 0.4.9+ cluster:
-
-```
-curl http://cluster.example.com:4001/v2/migration/snapshot > backup.snap
-```
-
-Now, import the snapshot into your new cluster:
-
-```
-etcdctl -C new_cluster.example.com import --snap backup.snap
-```
-
-If you have a large amount of data, you can specify more concurrent works to copy data in parallel by using `-c` flag.
-If you have hidden keys to copy, you can use `--hidden` flag to specify.
-
-And the data will quickly copy into the new cluster:
-
-```
-entering dir: /
-entering dir: /foo
-entering dir: /foo/bar
-copying key: /foo/bar/1 1
-entering dir: /
-entering dir: /foo2
-entering dir: /foo2/bar2
-copying key: /foo2/bar2/2 2
-```
-
 ## Key-Value API
 
 ### Read consistency flag

etcdserver/storage.go

@@ -20,7 +20,6 @@ import (
 	"path"
 
 	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
-	"github.com/coreos/etcd/migrate"
 	"github.com/coreos/etcd/pkg/pbutil"
 	"github.com/coreos/etcd/pkg/types"
 	"github.com/coreos/etcd/raft/raftpb"
@@ -109,14 +108,6 @@ func readWAL(waldir string, snap walpb.Snapshot) (w *wal.WAL, id, cid types.ID,
 // It must ensure that, after upgrading, the most recent version is present.
 func upgradeDataDir(baseDataDir string, name string, ver version.DataDirVersion) error {
 	switch ver {
-	case version.DataDir0_4:
-		plog.Infof("converting v0.4 log to v2.0")
-		err := migrate.Migrate4To2(baseDataDir, name)
-		if err != nil {
-			plog.Fatalf("failed to migrate data-dir (%v)", err)
-			return err
-		}
-		fallthrough
 	case version.DataDir2_0:
 		err := makeMemberDir(baseDataDir)
 		if err != nil {