diff --git a/lib/bcoin/chain.js b/lib/bcoin/chain.js
index b030ae12..448358f3 100644
--- a/lib/bcoin/chain.js
+++ b/lib/bcoin/chain.js
@@ -37,10 +37,11 @@ function Chain(options) {
   this.db = new bcoin.chaindb(this);
   this.request = new utils.RequestCache();
   this.loading = false;
-  this.tip = null;
-  this.height = -1;
   this.mempool = options.mempool;
   this.blockdb = options.blockdb;
+  this.resetting = false;
+  this.reverting = false;
+  this.syncing = false;
   this.locked = false;
   this.pending = [];
   this.pendingBlocks = {};
@@ -144,11 +145,6 @@ Chain.prototype._init = function _init() {
       self.mempool.removeBlock(block);
   });
 
-  this.db.on('tip', function(tip) {
-    self.tip = tip;
-    self.height = tip.height;
-  });
-
   this.loading = true;
 
   utils.debug('Chain is loading.');
@@ -179,22 +175,19 @@ Chain.prototype._init = function _init() {
   });
 };
 
+Chain.prototype.__defineGetter__('tip', function() {
+  return this.db.tip;
+});
+
+Chain.prototype.__defineGetter__('height', function() {
+  return this.db.height;
+});
+
 Chain.prototype._ensureGenesis = function _ensureGenesis(callback) {
   var self = this;
 
   callback = utils.asyncify(callback);
 
-  this.db.save(bcoin.chainblock.fromJSON(this, {
-    hash: network.genesis.hash,
-    version: network.genesis.version,
-    prevBlock: network.genesis.prevBlock,
-    merkleRoot: network.genesis.merkleRoot,
-    ts: network.genesis.ts,
-    bits: network.genesis.bits,
-    nonce: network.genesis.nonce,
-    height: 0
-  }));
-
   if (!this.blockdb)
     return callback();
 
@@ -681,6 +674,7 @@ Chain.prototype.resetHeight = function resetHeight(height) {
   var count = this.db.count();
   var i, existing;
 
+  assert(!this.resetting);
   assert(height <= count - 1);
   assert(this.tip);
 
@@ -704,17 +698,17 @@ Chain.prototype.resetHeightAsync = function resetHeightAsync(height, callback) {
   var count = this.db.count();
   var i, lock;
 
+  assert(!this.resetting);
   assert(height <= count - 1);
   assert(this.tip);
 
   if (height === count - 1)
     return utils.nextTick(callback);
 
-  lock = this.locked;
-  this.locked = true;
+  this.resetting = true;
 
   this.db.resetHeightAsync(height, function(err) {
-    self.locked = lock;
+    self.resetting = false;
 
     if (err)
       return callback(err);
@@ -735,16 +729,15 @@ Chain.prototype.resetHeightAsync = function resetHeightAsync(height, callback) {
 Chain.prototype.revertHeight = function revertHeight(height, callback) {
   var self = this;
   var chainHeight;
-  var lock = this.locked;
 
-  assert(!this.locked);
+  assert(!this.reverting);
 
   callback = utils.asyncify(callback);
 
-  this.locked = true;
+  this.reverting = true;
 
   function done(err, result) {
-    self.locked = lock;
+    self.reverting = false;
     callback(err, result);
   }
 
@@ -756,8 +749,7 @@ Chain.prototype.revertHeight = function revertHeight(height, callback) {
   if (!this.blockdb) {
     if (height > chainHeight)
       return done(new Error('Cannot reset height.'));
-    this.resetHeight(height);
-    return done();
+    return this.resetHeightAsync(height, done);
   }
 
   this.blockdb.getHeight(function(err, blockHeight) {
@@ -780,9 +772,7 @@ Chain.prototype.revertHeight = function revertHeight(height, callback) {
       if (err)
         return done(err);
 
-      self.resetHeight(height);
-
-      return done();
+      self.resetHeightAsync(height, done);
     }, function(block) {
       self.emit('remove block', block);
     });
@@ -791,32 +781,34 @@ Chain.prototype.revertHeight = function revertHeight(height, callback) {
 
 Chain.prototype._revertLast = function _revertLast(existing, callback) {
   var self = this;
-  return this._removeBlock(existing.hash, function(err, existingBlock) {
+  this._removeBlock(existing.hash, function(err, existingBlock) {
     if (err)
       return callback(err);
 
-    self.resetHeight(existing.height - 1);
+    self.resetHeightAsync(existing.height - 1, function(err) {
+      if (err)
+        return callback(err);
 
-    if (existingBlock)
-      self.emit('remove block', existingBlock);
+      if (existingBlock)
+        self.emit('remove block', existingBlock);
 
-    return callback();
+      return callback();
+    });
   });
 };
 
 Chain.prototype.syncHeight = function syncHeight(callback) {
   var self = this;
   var chainHeight;
-  var lock = this.locked;
 
   callback = utils.asyncify(callback);
 
-  assert(!this.locked);
+  assert(!this.syncing);
 
-  this.locked = true;
+  this.syncing = true;
 
   function done(err, result) {
-    self.locked = lock;
+    self.syncing = false;
     callback(err, result);
   }
 
@@ -842,8 +834,7 @@ Chain.prototype.syncHeight = function syncHeight(callback) {
 
     if (blockHeight < chainHeight) {
       utils.debug('BlockDB is higher than ChainDB. Syncing...');
-      self.resetHeight(blockHeight);
-      return done();
+      return self.resetHeightAsync(blockHeight, done);
     }
 
     if (blockHeight > chainHeight) {
@@ -874,6 +865,9 @@ Chain.prototype.add = function add(initial, peer, callback) {
 
   assert(!this.loading);
 
+  if (this.resetting || this.reverting || this.syncing)
+    return callback();
+
   if (this.locked) {
     this.pending.push([initial, peer, callback]);
     this.pendingBlocks[initial.hash('hex')] = true;
@@ -890,7 +884,7 @@ Chain.prototype.add = function add(initial, peer, callback) {
   (function next(block) {
     var hash = block.hash('hex');
     var prevHash = block.prevBlock;
-    var prevHeight, entry, existing, checkpoint, prev, orphan;
+    var prevHeight, entry, checkpoint, prev, orphan;
 
     // Special case for genesis block.
     if (block.isGenesis())
@@ -1018,52 +1012,54 @@ Chain.prototype.add = function add(initial, peer, callback) {
     }
 
     // See if the entry already exists.
-    existing = self.db.get(entry.height);
-
-    // Entry already exists.
-    if (existing) {
-      // We already have this block. Do regular
-      // orphan resolution (won't do anything).
-      // NOTE: Wrap this in a nextTick to avoid
-      // a stack overflow if there are a lot of
-      // existing blocks.
-      if (existing.hash === hash) {
-        self.emit('exists', block, {
-          height: entry.height,
-          hash: entry.hash
-        }, peer);
-        return utils.nextTick(handleOrphans);
-      }
-
-      // A valid block with an already existing
-      // height came in, that spells fork. We
-      // don't store by hash so we can't compare
-      // chainworks. We reset the chain, find a
-      // new peer, and wait to see who wins.
-      assert(self.db.getHeight(entry.hash) == null);
-
-      // The tip has more chainwork, it is a
-      // higher height than the entry. This is
-      // not an alternate tip. Ignore it.
-      if (self.tip.chainwork.cmp(entry.chainwork) > 0)
-        return done();
-
-      // The block has equal chainwork (an
-      // alternate tip). Reset the chain, find
-      // a new peer, and wait to see who wins.
-      // return self.revertHeight(existing.height - 1, function(err) {
-      return self._revertLast(existing, function(err, existingBlock) {
+    if (self.db.has(entry.height)) {
+      return self.db.getAsync(entry.height, function(err, existing) {
         if (err)
           return done(err);
 
-        self.emit('fork', block, {
-          height: existing.height,
-          expected: existing.hash,
-          received: entry.hash,
-          checkpoint: false
-        }, peer);
+        // We already have this block. Do regular
+        // orphan resolution (won't do anything).
+        // NOTE: Wrap this in a nextTick to avoid
+        // a stack overflow if there are a lot of
+        // existing blocks.
+        if (existing.hash === hash) {
+          self.emit('exists', block, {
+            height: entry.height,
+            hash: entry.hash
+          }, peer);
+          return utils.nextTick(handleOrphans);
+        }
 
-        return done();
+        // A valid block with an already existing
+        // height came in, that spells fork. We
+        // don't store by hash so we can't compare
+        // chainworks. We reset the chain, find a
+        // new peer, and wait to see who wins.
+        assert(self.db.getHeight(entry.hash) == null);
+
+        // The tip has more chainwork, it is a
+        // higher height than the entry. This is
+        // not an alternate tip. Ignore it.
+        if (self.tip.chainwork.cmp(entry.chainwork) > 0)
+          return done();
+
+        // The block has equal chainwork (an
+        // alternate tip). Reset the chain, find
+        // a new peer, and wait to see who wins.
+        // return self.revertHeight(existing.height - 1, function(err) {
+        return self._revertLast(existing, function(err, existingBlock) {
+          if (err)
+            return done(err);
+
+          self.emit('fork', block, {
+            height: existing.height,
+            expected: existing.hash,
+            received: entry.hash,
+            checkpoint: false
+          }, peer);
+
+          return done();
+        });
       });
     }
 
@@ -1071,6 +1067,8 @@ Chain.prototype.add = function add(initial, peer, callback) {
     assert(self.db.getHeight(entry.hash) == null);
 
     // Lookup previous entry.
+    // We can do this synchronously:
+    // it is already cached.
     prev = self.db.get(prevHeight);
     assert(prev);
 
@@ -1247,7 +1245,7 @@ Chain.prototype.byTime = function byTime(ts) {
 };
 
 Chain.prototype.hasBlock = function hasBlock(hash) {
-  return !!this.byHash(hash);
+  return this.db.has(hash);
 };
 
 Chain.prototype.hasOrphan = function hasOrphan(hash) {
@@ -1400,49 +1398,47 @@ Chain.prototype.getLocatorAsync = function getLocatorAsync(start, callback) {
     return callback(null, hashes);
   }
 
-  this.db.hasAsync(top, function(err, has) {
-    var pending;
+  try {
+    assert(this.db.has(top));
+  } catch (e) {
+    return done(new Error('Potential reset.'));
+  }
 
-    if (err)
-      return done(err);
+  var pending;
 
-    if (!has)
-      return done(new Error('Potential reset.'));
+  i = top;
+  for (;;) {
+    hashes.push(i);
+    i = i - step;
+    if (i <= 0) {
+      if (i + step !== 0)
+        hashes.push(0);
+      break;
+    }
+    if (hashes.length >= 10)
+      step *= 2;
+  }
 
-    i = top;
-    for (;;) {
-      hashes.push(i);
-      i = i - step;
-      if (i <= 0) {
-        if (i + step !== 0)
-          hashes.push(0);
-        break;
-      }
-      if (hashes.length >= 10)
-        step *= 2;
+  pending = hashes.length;
+
+  hashes.forEach(function(height, i) {
+    if (typeof height === 'string') {
+      if (!--pending)
+        done();
+      return;
     }
 
-    pending = hashes.length;
+    self.db.getAsync(height, function(err, existing) {
+      if (err)
+        return done(err);
 
-    hashes.forEach(function(height, i) {
-      if (typeof height === 'string') {
-        if (!--pending)
-          done();
-        return;
-      }
+      if (!existing)
+        return done(new Error('Potential reset.'));
 
-      self.db.getAsync(height, function(err, existing) {
-        if (err)
-          return done(err);
+      hashes[i] = existing.hash;
 
-        if (!existing)
-          return done(new Error('Potential reset.'));
-
-        hashes[i] = existing.hash;
-
-        if (!--pending)
-          done();
-      });
+      if (!--pending)
+        done();
     });
   });
 };
@@ -1467,11 +1463,11 @@ Chain.prototype.getOrphanRoot = function getOrphanRoot(hash) {
 };
 
 Chain.prototype.getHeight = function getHeight(hash) {
-  var entry = this.byHash(hash);
-  if (!entry)
+  var height = this.db.getHeight(hash);
+  if (height == null)
     return -1;
 
-  return entry.height;
+  return height;
 };
 
 Chain.prototype.getNextBlock = function getNextBlock(hash) {
diff --git a/lib/bcoin/chainblock.js b/lib/bcoin/chainblock.js
index a6c67935..657275f2 100644
--- a/lib/bcoin/chainblock.js
+++ b/lib/bcoin/chainblock.js
@@ -53,6 +53,8 @@ ChainBlock.prototype.getProof = function getProof() {
 };
 
 ChainBlock.prototype.getChainwork = function getChainwork() {
+  if (!this.chain.db)
+    return;
   var prev = this.prev;
   return (prev ? prev.chainwork : new bn(0)).add(this.getProof());
 };
diff --git a/lib/bcoin/chaindb.js b/lib/bcoin/chaindb.js
index 3585ccfd..7ddcc111 100644
--- a/lib/bcoin/chaindb.js
+++ b/lib/bcoin/chaindb.js
@@ -61,9 +61,21 @@ function ChainDB(chain, options) {
 inherits(ChainDB, EventEmitter);
 
 ChainDB.prototype._init = function _init() {
+  var genesis = bcoin.chainblock.fromJSON(this.chain, {
+    hash: network.genesis.hash,
+    version: network.genesis.version,
+    prevBlock: network.genesis.prevBlock,
+    merkleRoot: network.genesis.merkleRoot,
+    ts: network.genesis.ts,
+    bits: network.genesis.bits,
+    nonce: network.genesis.nonce,
+    height: 0
+  });
+
   if (!bcoin.fs) {
     utils.debug('`fs` module not available. Falling back to ramdisk.');
     this.ramdisk = new bcoin.ramdisk(40 * 1024 * 1024);
+    this.saveSync(genesis);
     return;
   }
 
@@ -88,6 +100,13 @@ ChainDB.prototype._init = function _init() {
   }
 
   this.fd = fs.openSync(this.file, 'r+');
+
+  if (this.size === 0) {
+    this.saveSync(genesis);
+  } else {
+    this.getSync(0);
+    assert(this.tip.hash === genesis.hash);
+  }
 };
 
 ChainDB.prototype.load = function load(start, callback) {
@@ -403,15 +422,19 @@ ChainDB.prototype.drop = function drop(height) {
 };
 
 ChainDB.prototype.resetHeight = function resetHeight(height) {
+  var size, count, existing;
+
   if (typeof height === 'string')
     height = this.heightLookup[height];
 
   assert(height >= 0);
 
-  var size = (height + 1) * BLOCK_SIZE;
-  var count = this.count();
+  size = (height + 1) * BLOCK_SIZE;
+  count = this.count();
+
   if (height === count - 1)
     return;
+
   assert(height <= count - 1);
   assert(this.tip);
 
@@ -422,19 +445,10 @@ ChainDB.prototype.resetHeight = function resetHeight(height) {
     delete this.heightLookup[existing.hash];
   }
 
-  if (!bcoin.fs) {
+  if (!bcoin.fs)
     this.ramdisk.truncate(size);
-
-    this.size = size;
-    this.highest = height;
-    this.tip = this.get(height);
-    assert(this.tip);
-    this.height = this.tip.height;
-    this.emit('tip', this.tip);
-    return;
-  }
-
-  fs.ftruncateSync(this.fd, size);
+  else
+    fs.ftruncateSync(this.fd, size);
 
   this.size = size;
   this.highest = height;
@@ -446,7 +460,7 @@ ChainDB.prototype.resetHeight = function resetHeight(height) {
 
 ChainDB.prototype.resetHeightAsync = function resetHeightAsync(height, callback) {
   var self = this;
-  var called;
+  var size, count, pending, called;
 
   if (typeof height === 'string')
     height = this.heightLookup[height];
@@ -455,15 +469,16 @@ ChainDB.prototype.resetHeightAsync = function resetHeightAsync(height, callback)
 
   callback = utils.asyncify(callback);
 
-  var size = (height + 1) * BLOCK_SIZE;
-  var count = this.count() - 1;
+  size = (height + 1) * BLOCK_SIZE;
+  count = this.count() - 1;
+  pending = count - (height + 1);
+
   if (height === count - 1)
     return callback();
+
   assert(height <= count - 1);
   assert(this.tip);
 
-  var pending = count - (height + 1);
-
   for (i = height + 1; i < count; i++)
     dropEntry(i);
 
@@ -491,12 +506,6 @@ ChainDB.prototype.resetHeightAsync = function resetHeightAsync(height, callback)
 
     if (!bcoin.fs) {
       self.ramdisk.truncate(size);
-      self.size = size;
-      self.highest = height;
-      self.tip = self.get(height);
-      assert(self.tip);
-      self.height = self.tip.height;
-      self.emit('tip', self.tip);
       return callback();
     }
 
@@ -583,6 +592,9 @@ ChainDB.prototype._readAsync = function _readAsync(size, offset, callback) {
         return callback(err);
       }
 
+      if (!bytes)
+        throw new Error('_readAsync() failed.');
+
       index += bytes;
       size -= bytes;
       offset += bytes;
@@ -655,6 +667,9 @@ ChainDB.prototype._writeAsync = function _writeAsync(data, offset, callback) {
         return callback(err);
       }
 
+      if (!bytes)
+        throw new Error('_writeAsync() failed.');
+
       index += bytes;
       size -= bytes;
       offset += bytes;