Hi,I have 2 nodes with RF of 2. I've added a secondary index (starttimeindex) recently to one of my column families (alerts) and executed the scrub command, but after restarting both of my nodes I got InstanceAlreadyExistsException for that index column family. it seems that cassandra made the index twice or even more (I updated the column family to add index several times actually) what should I do to fix it? I have seen this thread: http://mail-archives.apache.org/mod_mbox/cassandra-user/201109.mbox/%3CCALdd-zhUFLt3URDSK0aHSmqDj-N1KeyxoNN4rgZjjz13CAgFNg@mail.gmail.com%3E but it doesn't help me because both of my nodes have this problem so none of them start up.

INFO 11:15:13,647 Creating new index : ColumnDefinition{name=6964, validator=org.apache.cassandra.db.marshal.LongType, index_type=KEYS, index_name='compressedidindex'}
 INFO 11:15:13,657 Creating new index : ColumnDefinition{name=7374617274746f696d65, validator=org.apache.cassandra.db.marshal.LongType, index_type=KEYS, index_name='starttimeindex'}
 INFO 11:15:13,662 Creating new index : ColumnDefinition{name=737461727474696d6532, validator=org.apache.cassandra.db.marshal.LongType, index_type=KEYS, index_name='starttimeindex'}
 INFO 11:15:13,662 Submitting index build of alerts.starttimeindex for data in SSTableReader(path='/media/data/logcorrelation/alerts/logcorrelation-alerts-hd-2099-Data.db'), SSTableReader(path='/media/data/logcorrelation/alerts/logcorrelation-alerts-hd-2096-Data.db'), SSTableReader(path='/media/data/logcorrelation/alerts/logcorrelation-alerts-hd-2098-Data.db'), SSTableReader(path='/media/data/logcorrelation/alerts/logcorrelation-alerts-hd-2101-Data.db'), SSTableReader(path='/media/data/logcorrelation/alerts/logcorrelation-alerts-hd-2100-Data.db'), SSTableReader(path='/media/data/logcorrelation/alerts/logcorrelation-alerts-hd-2097-Data.db')
ERROR 11:15:13,664 Exception encountered during startup
java.lang.RuntimeException: javax.management.InstanceAlreadyExistsException: org.apache.cassandra.db:type=IndexColumnFamilies,keyspace=logcorrelation,columnfamily=alerts.starttimeindex
    at org.apache.cassandra.db.ColumnFamilyStore.<init>(ColumnFamilyStore.java:261)
    at org.apache.cassandra.db.ColumnFamilyStore.createColumnFamilyStore(ColumnFamilyStore.java:341)
    at org.apache.cassandra.db.ColumnFamilyStore.createColumnFamilyStore(ColumnFamilyStore.java:318)
    at org.apache.cassandra.db.index.keys.KeysIndex.init(KeysIndex.java:60)
    at org.apache.cassandra.db.index.SecondaryIndexManager.addIndexedColumn(SecondaryIndexManager.java:238)
    at org.apache.cassandra.db.ColumnFamilyStore.<init>(ColumnFamilyStore.java:247)
    at org.apache.cassandra.db.ColumnFamilyStore.createColumnFamilyStore(ColumnFamilyStore.java:341)
    at org.apache.cassandra.db.ColumnFamilyStore.createColumnFamilyStore(ColumnFamilyStore.java:313)
    at org.apache.cassandra.db.Table.initCf(Table.java:371)
    at org.apache.cassandra.db.Table.<init>(Table.java:304)
    at org.apache.cassandra.db.Table.open(Table.java:119)
    at org.apache.cassandra.db.Table.open(Table.java:97)
    at org.apache.cassandra.service.AbstractCassandraDaemon.setup(AbstractCassandraDaemon.java:204)
    at org.apache.cassandra.service.AbstractCassandraDaemon.activate(AbstractCassandraDaemon.java:353)
    at org.apache.cassandra.thrift.CassandraDaemon.main(CassandraDaemon.java:106)
Caused by: javax.management.InstanceAlreadyExistsException: org.apache.cassandra.db:type=IndexColumnFamilies,keyspace=logcorrelation,columnfamily=alerts.starttimeindex
    at com.sun.jmx.mbeanserver.Repository.addMBean(Unknown Source)
    at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.internal_addObject(Unknown Source)
    at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerDynamicMBean(Unknown Source)
    at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerObject(Unknown Source)
    at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerMBean(Unknown Source)
    at com.sun.jmx.mbeanserver.JmxMBeanServer.registerMBean(Unknown Source)
    at org.apache.cassandra.db.ColumnFamilyStore.<init>(ColumnFamilyStore.java:257)
    ... 14 more
java.lang.RuntimeException: javax.management.InstanceAlreadyExistsException: org.apache.cassandra.db:type=IndexColumnFamilies,keyspace=logcorrelation,columnfamily=alerts.starttimeindex
 INFO 11:15:13,665 reading saved cache /media/data/saved_caches/logcorrelation-alerts-KeyCache
    at org.apache.cassandra.db.ColumnFamilyStore.<init>(ColumnFamilyStore.java:261)
    at org.apache.cassandra.db.ColumnFamilyStore.createColumnFamilyStore(ColumnFamilyStore.java:341)
    at org.apache.cassandra.db.ColumnFamilyStore.createColumnFamilyStore(ColumnFamilyStore.java:318)
    at org.apache.cassandra.db.index.keys.KeysIndex.init(KeysIndex.java:60)
    at org.apache.cassandra.db.index.SecondaryIndexManager.addIndexedColumn(SecondaryIndexManager.java:238)
    at org.apache.cassandra.db.ColumnFamilyStore.<init>(ColumnFamilyStore.java:247)
    at org.apache.cassandra.db.ColumnFamilyStore.createColumnFamilyStore(ColumnFamilyStore.java:341)
    at org.apache.cassandra.db.ColumnFamilyStore.createColumnFamilyStore(ColumnFamilyStore.java:313)
    at org.apache.cassandra.db.Table.initCf(Table.java:371)
    at org.apache.cassandra.db.Table.<init>(Table.java:304)
    at org.apache.cassandra.db.Table.open(Table.java:119)
    at org.apache.cassandra.db.Table.open(Table.java:97)
    at org.apache.cassandra.service.AbstractCassandraDaemon.setup(AbstractCassandraDaemon.java:204)
    at org.apache.cassandra.service.AbstractCassandraDaemon.activate(AbstractCassandraDaemon.java:353)
    at org.apache.cassandra.thrift.CassandraDaemon.main(CassandraDaemon.java:106)
Caused by: javax.management.InstanceAlreadyExistsException: org.apache.cassandra.db:type=IndexColumnFamilies,keyspace=logcorrelation,columnfamily=alerts.starttimeindex
    at com.sun.jmx.mbeanserver.Repository.addMBean(Unknown Source)
    at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.internal_addObject(Unknown Source)
    at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerDynamicMBean(Unknown Source)
    at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerObject(Unknown Source)
    at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerMBean(Unknown Source)
    at com.sun.jmx.mbeanserver.JmxMBeanServer.registerMBean(Unknown Source)
    at org.apache.cassandra.db.ColumnFamilyStore.<init>(ColumnFamilyStore.java:257)
    ... 14 more
Exception encountered during startup: javax.management.InstanceAlreadyExistsException: org.apache.cassandra.db:type=IndexColumnFamilies,keyspace=logcorrelation,columnfamily=alerts.starttimeindex