With current hardware, SAP HANA can scale up to 6TB for a single system, and can scale out to 112TB in a cluster, or more. There is no hard technical limit to the size of a HANA cluster. Higher configurations are tested and certified at customer sites.
We are currently working with 24TB single systems with SAP that we expect to see this year.
At Bluefin, we regularly work with 2-10TB of memory in a single HANA DB, and this is where we find most business cases make sense. Remember that a 10TB HANA appliance can store a vast amount of data (as much as 50-100TB from a traditional RDBMS due to HANA’s data compression capabilities); this could represent all the credit card transactions for a top 10 bank for 10 years or more.
In addition, we find that customers look to be more intelligent about how they tier data with an in-memory appliance. Once the HANA database grows past 2TB, it makes a lot of sense to use a cold store like Sybase IQ for slow-changing data.