No Load balancers in front of cassandra Cassandra distributes the data across the nodes and most of the cassandra drivers have the algorithm built in to direct requests appropriately . Adding load balancer introduces an additional layer , potentially breaks intelligent algorithms used by driver and also introduces a single point of failure where there …

Decrease the default read ahead values in unix/linux systems Most of the modern unix/linux systems use read ahead so that subsequent reads will be cached in to memory . This provides a performance benefit for systems that read data sequentially (e.g. Kafka) .However, in cassandra most normal read operations are not sequential and hence read …

We get this error when we start our Cassandra recently. New main PID x does not belong to service, and PID file is not owned by root. Refusing. After checking, we found that it is a bug for cassandra startup file. Error Log for Unit Cassandra.service entered failed state systemctl status cassandra cassandra.service – LSB: …

Sometimes when we ssh to Linux box, we get this error “WARNING: Your password has expired.” You must change your password now and login again! Changing password for user ocp. Changing password for ocp.” What does “WARNING: Your password has expired.” mean? That means the password for this account expired. We need to change the …

Cassandra uses data partitions to distribute data to each node. Partitions are based on the partition keys. Partition function(partition key) = token number. Apache Cassandra Data Partitions Apache Cassandra, a NoSQL database, belongs to the big data family of applications and operates as a distributed system, and uses the principle of data partitioning as explained …

Apache Cassandra supports two kinds of backup strategies. Snapshots Incremental Backups A snapshot is a copy of a table’s SSTable files at a given time, created via hard links. The DDL to create the table is stored as well. Snapshots may be created by a user or created automatically. The setting (snapshot_before_compaction) in cassandra.yaml determines …

Cassandra timeout issue is a complex issue. Today we will review what read timeout mean in Cassandra and how to fix it. what does Read timeout mean in Cassandra cluster? A read request reached the coordinator, which initially believed that there were enough live replicas to process it. But, for some reason, one or several …

Rp_filter is short for reverse path filtering on Linux. We can use this to filter packets on Linux. Here are 5 common questions about rp_filter. What is reverse path filtering? Reverse path filtering is a mechanism adopted by the Linux kernel, as well as most of the networking devices out there to check whether a …

Apache Cassandra cluster is a distributed system. Monitoring this cluster is not an easy task. There are a few monitoring tools for Cassandra in the market. Most of them are commercial products. Today we are going to use open source software to monitor Cassandra cluster. Monitor Cassandra with TIG System In our env, we use …

NFS performance is important for the production environment. In this tutorial, we will review how to use DD command to test local storage and NFS storage performance. Test nfs storage performance on Linux There are some differences between each testing command. We choose dd command in the following example. dd – without conv=fsync or oflag=direct. …