Aiven now supports sstableloader, an open source utility which allows you to easily migrate all of the data from your external Apache Cassandra instances into a managed Aiven Cassandra cluster. Sstableloader allows this seamless migration by bulk-loading data from remote SSTables into an Aiven Cassandra cluster via the target nodes’ internode ports.
How sstableloader works
An SStable is a persistent, immutable file format where your Cassandra data is stored. It is created when fast memory stores called memtables are flushed to disk. Sstableloader works by first connecting to the new Cassandra cluster to determine which nodes of the target cluster should receive which rows, then uploading the SSTable data to the target nodes.
This data upload - called streaming - is implemented as a command line client using the same Java code the Cassandra service uses internally to replicate data between cluster nodes, connecting to the Cassandra internode port to achieve a more efficient way to transfer large amounts of data.
Clients cannot normally connect to this internode port, and Aiven requires sstableloader to connect with SSL through client certificates to secure access. As a result, large clusters for which inserting the source cluster's data row by row with CQL would take unfeasibly long can now be migrated.
With sstableloader, you now have the industry standard for bulk data loading into Cassandra which makes migrating your full data pipeline to Aiven that much simpler.
You can find the complete procedure here.