What does Nodetool repair do?

What does Nodetool repair do?

Repairs one or more tables. The repair command repairs one or more nodes in a cluster, and provides options for restricting repair to a set of nodes, see Repairing nodes. Performing an anti-entropy node repair on a regular basis is important, especially in an environment that deletes data frequently.

How do I run Nodetool repair?

Procedure

1. Log in to the server where a Cassandra node is installed.
2. Go to the /apache-cassandra/bin directory.
3. Type ./nodetool repair -local to run an incremental, parallel repair. Add -full -local to run a full repair. Add -seq to run a sequential repair. Examples: ./nodetool repair -seq -local.

When should I run Cassandra repair?

If you don’t want to run incremental repairs, a full repair every 5 days is a good place to start. At a minimum, repair should be run often enough that the gc grace period never expires on unrepaired data. Otherwise, deleted data could reappear.

When should I run Nodetool cleanup?

You should run nodetool cleanup whenever you scale-out (expand) your cluster, and new nodes are added to the same DC. The scale out process causes the token ring to get re-distributed. As a result, some of the nodes will have replicas for tokens that they are no longer responsible for (taking up disk space).

What does Nodetool scrub do?

Rebuilds SSTables for one or more tables. Creates a snapshot and then rebuilds SSTables on a node. If possible use nodetool upgradesstables instead of scrub.

What is Nodetool flush?

Flushes one or more tables from the memtable to SSTables on disk. Flushes one or more tables from the memtable to SSTables on disk. OpsCenter provides a flush option for Flushing tables in Nodes.

What is Nodetool in Cassandra?

The nodetool utility is a command line interface for Cassandra. You can use it to help manage a cluster. In binary installations, nodetool is located in the /bin directory. Square brackets indicate optional parameters.

How do I clean my Cassandra database?

To clear the data from the default directories:

1. After Stop the service.
2. Run the following command: sudo rm -rf /var/lib/cassandra/* ## Remove all data $ sudo rm -rf /var/lib/cassandra/data/* ## Remove only the data directories.

What are Cassandra SSTables?

SSTables are the immutable data files that Cassandra uses for persisting data on disk. As SSTables are flushed to disk from memtables or are streamed from other nodes, Cassandra triggers compactions which combine multiple SSTables into one. Once the new SSTable has been written, the old SSTables can be removed.

How long does Nodetool drain take?

nodetool drain taking around 2 to 3 hours.

What is Nodetool cleanup?

Triggers immediate cleanup of keyspaces that no longer belong to a node. Triggers immediate cleanup of keyspaces that no longer belong to a node. OpsCenter provides a Cleanup option in the Nodes UI for Running cleanup.

What is TTL in Cassandra?

In Cassandra Both the INSERT and UPDATE commands support setting a time for data in a column to expire. It is used to set the time limit for a specific period of time. By USING TTL clause we can set the TTL value at the time of insertion. We can use TTL function to get the time remaining for a specific selected query.