diff --git a/hstream/app/server.hs b/hstream/app/server.hs
index 1dfe62724..2de90993b 100644
--- a/hstream/app/server.hs
+++ b/hstream/app/server.hs
@@ -2,6 +2,7 @@
 {-# LANGUAGE DataKinds           #-}
 {-# LANGUAGE GADTs               #-}
 {-# LANGUAGE LambdaCase          #-}
+{-# LANGUAGE NamedFieldPuns      #-}
 {-# LANGUAGE OverloadedRecordDot #-}
 {-# LANGUAGE OverloadedStrings   #-}
 {-# LANGUAGE RecordWildCards     #-}
@@ -35,7 +36,8 @@ import           HStream.Common.Server.HashRing   (updateHashRing)
 import           HStream.Common.Server.MetaData   (TaskAllocation (..),
                                                    clusterStartTimeId)
 import           HStream.Common.Types             (getHStreamVersion)
-import           HStream.Common.ZookeeperClient   (withZookeeperClient)
+import           HStream.Common.ZookeeperClient   (unsafeGetZHandle,
+                                                   withZookeeperClient)
 import           HStream.Exception
 import           HStream.Gossip                   (GossipContext (..),
                                                    defaultGossipOpts,
@@ -61,6 +63,8 @@ import           HStream.Server.Config            (AdvertisedListeners,
                                                    getConfig, runServerCli)
 import qualified HStream.Server.Core.Cluster      as Cluster
 import qualified HStream.Server.Experimental      as Exp
+import           HStream.Server.HealthMonitor     (mkHealthMonitor,
+                                                   startMonitor)
 import qualified HStream.Server.HsGrpcHandler     as HsGrpcHandler
 import qualified HStream.Server.HStreamApi        as API
 import qualified HStream.Server.HStreamInternal   as I
@@ -174,6 +178,13 @@ app config@ServerOpts{..} = do
         forM_ as (Async.link2Only (const True) a)
         -- wati the default server
         waitGossipBoot gossipContext
+
+        let ServerContext{scLDClient, metaHandle} = serverContext
+        healthMonitor <- mkHealthMonitor scLDClient metaHandle 1
+        aMonitor <- Async.async $ startMonitor serverContext healthMonitor 3
+        Log.info $ "Start healthy monitor"
+        Async.link2Only (const True) a aMonitor
+
         Async.wait a
 
 serve
diff --git a/hstream/src/HStream/Server/Core/Stream.hs b/hstream/src/HStream/Server/Core/Stream.hs
index 95d97c851..ce197bdd5 100644
--- a/hstream/src/HStream/Server/Core/Stream.hs
+++ b/hstream/src/HStream/Server/Core/Stream.hs
@@ -36,6 +36,7 @@ import qualified Data.ByteString                   as BS
 import qualified Data.ByteString.Lazy              as BSL
 import           Data.Either                       (partitionEithers)
 import           Data.Functor                      ((<&>))
+import           Data.IORef                        (readIORef)
 import qualified Data.List                         as L
 import qualified Data.Map.Strict                   as M
 import           Data.Maybe                        (fromJust, fromMaybe)
@@ -52,10 +53,12 @@ import           HStream.Common.Types
 import qualified HStream.Common.ZookeeperSlotAlloc as Slot
 import qualified HStream.Exception                 as HE
 import qualified HStream.Logger                    as Log
+import qualified HStream.Server.CacheStore         as DB
 import qualified HStream.Server.HStreamApi         as API
 import qualified HStream.Server.MetaData           as P
 import           HStream.Server.Types              (ServerContext (..),
                                                     ServerInternalOffset (..),
+                                                    ServerMode (..),
                                                     ToOffset (..))
 import qualified HStream.Stats                     as Stats
 import qualified HStream.Store                     as S
@@ -385,7 +388,11 @@ appendStream ServerContext{..} streamName shardId record = do
       recordSize = API.batchedRecordBatchSize record
       payloadSize = BS.length payload
   when (payloadSize > scMaxRecordSize) $ throwIO $ HE.InvalidRecordSize payloadSize
-  S.AppendCompletion {..} <- S.appendCompressedBS scLDClient shardId payload cmpStrategy Nothing
+  -- S.AppendCompletion {..} <- S.appendCompressedBS scLDClient shardId payload cmpStrategy Nothing
+  state <- readIORef serverState
+  S.AppendCompletion {..} <- case state of
+    ServerNormal -> S.appendCompressedBS scLDClient shardId payload cmpStrategy Nothing
+    ServerBackup -> DB.writeRecord cachedStore streamName shardId payload
   Stats.stream_stat_add_append_in_bytes scStatsHolder cStreamName (fromIntegral payloadSize)
   Stats.stream_stat_add_append_in_records scStatsHolder cStreamName (fromIntegral recordSize)
   Stats.stream_time_series_add_append_in_bytes scStatsHolder cStreamName (fromIntegral payloadSize)
diff --git a/hstream/src/HStream/Server/Initialization.hs b/hstream/src/HStream/Server/Initialization.hs
index 37c21ab1e..48ac5ef27 100644
--- a/hstream/src/HStream/Server/Initialization.hs
+++ b/hstream/src/HStream/Server/Initialization.hs
@@ -40,6 +40,7 @@ import qualified Z.Data.CBytes                    as CB
 #if __GLASGOW_HASKELL__ < 902
 import qualified HStream.Admin.Store.API          as AA
 #endif
+import           Data.IORef                       (newIORef)
 import           HStream.Common.ConsistentHashing (HashRing, constructServerMap,
                                                    getAllocatedNodeId)
 import           HStream.Common.Server.HashRing   (initializeHashRing)
@@ -49,6 +50,7 @@ import qualified HStream.IO.Types                 as IO
 import qualified HStream.IO.Worker                as IO
 import qualified HStream.Logger                   as Log
 import           HStream.MetaStore.Types          (MetaHandle (..))
+import           HStream.Server.CacheStore        (mkCacheStore)
 import           HStream.Server.Config            (ServerOpts (..),
                                                    TlsConfig (..))
 import           HStream.Server.Types
@@ -88,6 +90,11 @@ initializeServer opts@ServerOpts{..} gossipContext hh db_m = do
 
   shardReaderMap <- newMVar HM.empty
 
+  serverMode <- newIORef ServerNormal
+  let dbOption = def { RocksDB.createIfMissing = True }
+  let path = _cacheStorePath <> show _serverID
+  cachedStore <- mkCacheStore path dbOption def def
+
   -- recovery tasks
 
   return
@@ -112,6 +119,8 @@ initializeServer opts@ServerOpts{..} gossipContext hh db_m = do
       , shardReaderMap           = shardReaderMap
       , querySnapshotPath        = _querySnapshotPath
       , querySnapshotter         = db_m
+      , serverState              = serverMode
+      , cachedStore              = cachedStore
       }
 
 --------------------------------------------------------------------------------