Occasionally the question arises: why can't a cluster be scaled so that only the storage capacity increases?
The reason for this is that CrateDB Cloud's plans operate on Database Transaction Units (DTUs). Each of these units constitutes a certain preconfigured combination of hardware, supporting both a given storage capacity and a given ingest and query capacity. The precise configuration represented by one DTU varies per CrateDB Cloud subscription plan.
The advantage of DTUs is that the customer does not have to worry about creating the correct hardware combination themselves, but can rely on the plans and their different scale units to find the combination that matches their particular use case. This means, however, that scaling (increasing DTUs) will increase both storage and ingest and query capacity at once.
We do, however, offer a Storage Optimized subscription plan. This plan is specifically geared towards users who require a storage-heavy database solution. For more information about our plans and DTUs, refer to our documentation on the subject.