HCD migration toolkit
The Hyper-Converged Database (HCD) migration toolkit includes the DataStax migration tools that you can use to migrate your data to HCD from another Apache Cassandra®-based database, such as Astra DB, Cassandra, or DSE.
Whenever possible, DataStax strongly recommends using the Zero Downtime Migration (ZDM) tools to orchestrate ongoing read/write traffic when you migrate to HCD.
Zero-downtime migrations to HCD
The Zero Downtime Migration (ZDM) tools allow you to standup your new HCD clusters independently of your existing DSE clusters. Then, ZDM Proxy orchestrates live traffic and synchronizes ongoing writes while you migrate data to your new clusters using any ZDM-compatible data migration and validation tool. Finally, you can use ZDM Proxy to simulate the live workload on your new clusters before permanently switching your traffic over.
ZDM Proxy and ZDM Proxy Automation provide the safest upgrade approach with blue-green deployment capabilities that eliminate time pressure and ensure optimal availability and operational safety. You can rollback up to the last stage of the migration if necessary.
By orchestrating independent clusters with the ZDM tools, you can specify your ideal HCD configuration settings that you otherwise wouldn’t be able to change during an in-place cluster upgrade. Incompatibilities in cluster configuration don’t disrupt the migration because your existing cluster remains active and unchanged while you set up the new cluster and migrate your data.
Data validation with ZDM
The ZDM tools don’t migrate your data. During the ZDM process, you use a data migration tool to rewrite the data from your existing cluster to your new cluster.
DataStax recommends that you do the following:
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Choose a data migration tool that also includes strong validation capabilities, such as Cassandra Data Migrator (CDM).
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Be aware of incompatible data types that can fail to migrate from your old cluster.
Data validation tools can identify inconsistencies as missing or mismatched data, but you still need to have a plan to resolve them. For example, you might need to modify your applications to use a different data type or perform additional post-migration writes to populate lost data.
It is crucial that you fully validate and test your new cluster before switching your traffic over to it.
ZDM Proxy is ideal for supporting this transition because it allows both clusters to remain in place until you are completely certain you are ready to switch to the new cluster. Additionally, your old cluster remains untouched and available for rollback or reversion if necessary.
Get started with ZDM and HCD
For information about clusters that are eligible for Zero Downtime Migration to HCD, see Cluster compatibility for Zero Downtime Migration.
To begin your Zero Downtime Migration to HCD, go to Phases of the Zero Downtime Migration process.
You must set up your HCD clusters before you can enable the ZDM Proxy. For information about installing and configuring HCD, see the HCD documentation.
Migrate your code
After migrating your data to HCD, your applications can connect exclusively to your new databases.
If you are already using a compatible Cassandra driver, you can modify the driver connection string to connect to the new or upgraded databases.
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Your Cassandra driver version must be compatible with HCD. If you are using an early driver version or a DSE-only driver, you must upgrade to a driver version that is compatible with HCD. For more information, see Cassandra drivers supported by DataStax. |
For some migrations, changing the connection string might be the only change you need to make to your code. However, you might want to update your code to take advantage of features and improvements available in your new database platform or a newer driver version.
For example, HCD includes an Astra Data API server that you can use for application development with your HCD databases, including vector search and hybrid search capabilities. It provides several client libraries and direct access over HTTP.
For more information about connecting to HCD databases, see the HCD documentation.
Get support for your migration
If you have questions about your HCD migration, contact your DataStax account representative or DataStax Support.
