HUnavailableException: : May not be enough replicas present to handle consistency level.

[Codevally]

Hi

I have 4 nodes Cassandra cluster in production with 1.0.11 version (hector 1.0.5).

Keyspace: MessageCache:

  Replication Strategy: org.apache.cassandra.locator.SimpleStrategy

  Durable Writes: true

    Options: [replication_factor:4]

  Column Families:

    ColumnFamily: MessageData

      Key Validation Class: org.apache.cassandra.db.marshal.BytesType

      Default column value validator: org.apache.cassandra.db.marshal.BytesType

      Columns sorted by: org.apache.cassandra.db.marshal.BytesType

      Row cache size / save period in seconds / keys to save : 0.0/0/all

      Row Cache Provider: org.apache.cassandra.cache.ConcurrentLinkedHashCacheProvider

      Key cache size / save period in seconds: 20000.0/3600

      GC grace seconds: 3600

      Compaction min/max thresholds: 4/32

      Read repair chance: 1.0

      Replicate on write: true

      Bloom Filter FP chance: default

      Built indexes: []

      Compaction Strategy: org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy

To increase the number of cores, I shutdown one Cassandra node and suddenly I got this exception.

me.prettyprint.hector.api.exceptions.HUnavailableException: : May not be enough replicas present to handle consistency level.

I have not mention any consistency level, so by default it should be QUORAM. 

According to the documentation, cluster can be survive with 3 live nodes (even one node goes offline), because of my replication factor RF=4.

If so why I am hitting this error?

Thanks

Roshan