通过python脚本更新cassandra表时出错

Question

我正在尝试通过以下脚本更新Cassandra表。

import requests
import json
import os
from cassandra import ConsistencyLevel
from cassandra.cluster import Cluster
from cassandra.query import SimpleStatement
from cassandra.auth import PlainTextAuthProvider
from cassandra.cqlengine import connection

def main():

        pogid_supcs = open("supcpog","r")

        print "Connecting to Cassandra \n"
        auth_provider = PlainTextAuthProvider(username='XXX', password='XYZEW')
        cluster = Cluster(['10.65.120.27','10.65.120.2','10.65.120.24','10.70.120.22','10.70.120.24','10.70.120.23'],auth_provider = auth_provider)
        session = cluster.connect()
        lines = pogid_supcs.readlines()
        pogid_supcs.close()

        attributes = open("attributesBackup40.txt","w")
        attributeError = open("attributeError1.txt","a")
        #attributes.write("     pog_id  |       supc            |       attribute_name  |       value   |\n")

        for line in lines:
                #try:
                pogid = long(line.split(",")[1]);
                supc = ((line.split(",")[0]).strip()).upper();
                print pogid
                print supc
                statement="update cams_web.product_full set catalog_status='TERMINATED' where pog_id = "+str(pogid)+" and supc = '"+supc+"';"
                print statement
                session.execute(statement)
                #       results = session.execute(statement)
        #               for rows in results:
                #       print rows.pog_id
        #                       val=(rows.value).encode('ascii','ignore')
        #                       attributes.write(str(rows.pog_id)+","+str(rows.supc)+","+str(rows.attribute_name)+","+str(rows.bucket_id)+","+str(rows.sub_partition)+","+str(rows.attribute_class)+","+str(rows.brand_id)+","+str(rows.created)+","+str(rows.priority)+","+str(rows.updated)+","+val+"\n")
        #               attributes.write("\n")
        #       except:
                        #attributeError.write(pogid"\n")
        attributes.close()


if __name__ == "__main__" :
        main()

当我在脚本中登录这些机器之一并运行更新查询时，该语句运行良好，但是当我尝试通过脚本执行查询时，出现以下错误。

Error from server: code=1000 [Unavailable exception] message="Cannot achieve consistency level LOCAL_ONE" info={'required_replicas': 1, 'alive_replicas': 0, 'consistency': 'LOCAL_ONE'}

我要连接的所有计算机都已启动。