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Cassandra for Oracle DBA’s Part 18 : Change of Replication Factor & Repair Nodes

As like in ASM, when ever a disk is added a rebalance operation takes place between the disks, similarly when the replication factor is changed at keyspace level in the cassandra, the rebalance operation should take place, I have changed the replication factor for Keyspace and you should start the repair of each node so […]

Cassandra for Oracle DBA’s Part 14: Tombstones – Undo type structures

Undo like pointers, tombstones

Cassandra uses a log-structured storage engine. Because of this, deletes do not remove the rows and columns immediately and in-place. Instead, Cassandra writes a special marker, called a tombstone, indicating that a row, column, or range of columns was deleted. These tombstones are kept for at least the period of time […]

Cassandra for Oracle DBA’s Part 16 : Shutting Down Best Practices

Shutdown Best Practice While Cassandra is crash-safe, you can make a cleanershutdown and save some time during startup thus:

– Make other nodes think this one is down.

– nodetool -h $(hostname) -p 8080 disablegossip

– Wait a few secs, cut off anyone from writing to this node.

– nodetool -h $(hostname) -p […]

Cassandra for Oracle DBA’s Part 15 : Partition Merging & Compacting

Partition Merging or Compact or merging ss tables

Cassandra does not do in-place writes or updates. Rather, it uses a log structured format. Writes are done to Memtables, which are periodically flushed to disk as SSTables. As a result of this approach, the number of SSTables grows over time.

Having multiple SSTables causes […]

Cassandra for Oracle DBA’s Part 17: Backup & Recovery

Backup in Cassandra maintain at node level , so any backup that taken in the one node does not contain other nodes data, so you must take backup of each node, cassandra maintains backups as snapshots means an entire sstables at disk level copied to a different folder with snapshot id as like below.

root@wash-i-16ca26c8-prod […]

Cassandra for Oracle DBA Part 17: Tracing Sessions

As like oracle 100046 , you can also trace the Cassandra Session and it provide you the following information , the highlighted blue parts are important to understand that data has been fetched from different nodes and how many undo it has to read and how many from cache and how many reads […]

Cassandra for Oracle DBA’s Part 13 : Memory Management

#############

Memory Calculation for Cassandra (kind of sga setting 🙂 will be done during environment setup with following script excerpt. if you want you can change accordingly this script and restart the cassandra.

##################

geek_cluster/node1/resources/cassandra/conf/cassandra-env.sh

….

half_system_memory_in_mb=`expr $system_memory_in_mb / 2`

quarter_system_memory_in_mb=`expr $half_system_memory_in_mb / 2`

if [ “$half_system_memory_in_mb” -gt “1024” ]

then

[…]

Cassandra for Oracle DBA’s Part 12 : Client Connections & Timeouts

We also set timeouts for client side,

TNSNAMES.ora or sqlnet.ora (Client Side)

root@wash-i-16ca26c8-prod ~/.ccm/repository/4.5.2/resources/cassandra/conf $ vi cqlshrc.default

root@wash-i-16ca26c8-prod ~/.ccm/repository/4.5.2/resources/cassandra/conf $

Set the client_timeout as like sqlnet.ora timeout setting

[connection]

hostname = 192.168.1.2

port = 9160

client_timeout=40

###################################

Node Communication Settings * Timeouts

###################################

root@wash-i-16ca26c8-prod ~/.ccm/geek_cluster/node1/resources/cassandra/conf $

root@wash-i-16ca26c8-prod ~/.ccm/geek_cluster/node1/resources/cassandra/conf […]

Cassandra for Oracle DBA’s Part 11 : Alert log & Tracing

Alert Log and tracing Parameters in Cassandra.yaml

log4j-server.properties

log4j.appender.R.File=/root/.ccm/geek_cluster/node1/logs/system.log

root@wash-i-16ca26c8-prod ~ $ ccm node1 nodetool getlogginglevels

Logger Name Log Level

root INFO

org.apache.solr.core.SolrCore WARN

org.apache.thrift.server.TNonblockingServer FATAL

org.apache.solr.handler.component WARN

org.apache.solr.search.SolrIndexSearcher WARN

org.apache.solr.update WARN

org.apache.solr.core.CassandraSolrConfig WARN

SolrValidationLog INFO

org.apache.solr.core.RequestHandlers WARN

org.apache.solr.util.plugin.AbstractPluginLoader WARN

root@wash-i-16ca26c8-prod ~ $

root@wash-i-16ca26c8-prod ~/.ccm/geek_cluster/node1/logs $ ls -ltr

total 528

[…]

Cassandra for Oracle DBA’s Part 10: Commit Logs (Managing Archivelogs & Redlogs)

Archive Logs & Redologs (commit logs) Parameters that need to effect.

commitlog_directory: /root/.ccm/geek_cluster/node1/commitlogs

commitlog_directory: /root/.ccm/geek_cluster/node1/commitlogs

commitlog_segment_size_in_mb: 32

commitlog_sync: periodic

commitlog_sync_period_in_ms: 10000

/.ccm/geek_cluster/node1/resources/cassandra/conf/commitlog_archiving.properties file to keep archive_command

Argument 1 will give you the path to the files you’d want to copy, while