SAP HANA dynamic tiering is an optional add-on to the SAP HANA database for managing historical data. Its purpose is to extend SAP HANA memory with a disk-centric columnar store (as opposed to SAP HANA’s in-memory store) for managing less frequently accessed warm data. Warm data has relaxed performance requirements compared to highly active “hot” data. Data in the extended store is on-line, and available for both queries and updates.
SAP HANA dynamic tiering provides the ability to create, load data into, and query disk-based, columnar database tables – called extended tables - in addition to the traditional column- or row-oriented in-memory tables of the SAP HANA database. With SAP HANA Dynamic Tiering 2.0 SP 00, SAP HANA introduced a new database object called a multistore table. A multistore table is a type of partitioned SAP HANA column table that has partitions in both SAP HANA default column storage, and dynamic tiering extended storage.
Like in-memory tables, extended and multistore tables are first-class database objects with full ACID compliance. All database requests regarding extended and multistore tables are integrated into SAP HANA’s transactional context. Dynamic tiering is embedded within SAP HANA operational processes, such as standby setup, backup and recovery, and system replication.
Dynamic tiering is also supported by the Data Lifecycle Manager (DLM), an SAP HANA XS-based tool to relocate data from SAP HANA memory to alternate storage locations such as the dynamic tiering extended store, SAP IQ, or Hadoop/Vora. With DLM, you can model aging rules on SAP HANA tables, and migrate data at specified times between high performance SAP HANA memory and a lower cost storage and processing tier. With SAP HANA Dynamic Tiering 2.0 SP 02, DLM supports only extended tables, and not multistore tables.
The SAP HANA dynamic tiering server is installed in production environments on its own machine:
The HANA host and the dynamic tiering hosts must share certain directories on a shared file system such as NFS (Network File System) or GPFS (General Parallel File System). The directories include the directory which contains executable programs and other shared data (default is /hana/shared) and the data backup area. SAP HANA dynamic tiering uses the same directories for data and log backups as SAP HANA.
New Feature in SAP HANA Dynamic Tiering 2.0 SP 02
The key new features in SAP HANA Dynamic Tiering 2.0 SP 02 are :
- Enhanced support for SAP HANA system replication: in addition to the existing support for 2-tier synchronous SAP HANA system replication, dynamic tiering now supports 2-tier asynchronous and 3-tier SAP HANA system replication. You may use delta-enabled extended or multistore tables only with two-tier synchronous replication.
- Support for active-active operation (read-only queries on the secondary system). However, dynamic tiering data is excluded from queries on the secondary system. Essentially, dynamic tiering does not interfere with active-active, but does not fully participate.
- Support for delta synchronization of a failback SAP HANA system replication site. Prior to SP 02, full data shipping was required.
- Incorporation of dynamic tiering into SAP’s test kit for hypervisor vendors to self-certify SAP HANA dynamic tiering for their virtualization environments. With this certification, SAP HANA and dynamic tiering must be co-deployed on the same virtual machine.
- Significant performance improvements with dynamic tiering:
- Full support for the MERGE INTO SQL statement for multistore tables.
- New escape character option for the IMPORT statement.
High-Level System Characteristics
SAP HANA dynamic tiering exists within the SAP HANA system architecture as a dedicated database process, named esserver. Like the indexserver process, which stores and processes in-memory data, the esserver process stores data in columnar, disk-based structures and offers disk-optimized data processing.
Dynamic tiering is an integrated storage and processing tier within the SAP HANA database. There is a common transaction context across all processes of the SAP HANA system. Relevant processes such as backup and recovery, and system replication include dynamic tiering data if dynamic tiering is installed on the SAP HANA system.
SAP HANA systems configured with multitenant database containers (MDC) can use dynamic tiering. A dedicated esserver process and dynamic tiering extended store is required for each tenant database using dynamic tiering. Currently, dynamic tiering does not support high tenant isolation within MDC environments.
Dynamic tiering is not scale-out enabled. Only one dynamic tiering worker host and one optional dynamic tiering standby host is allowed for each database in an SAP HANA system. The in-memory part of the SAP HANA system can be a scale-out setup with multiple hosts running indexserver processes.
Sizing and Implementation Approach
Since SAP HANA dynamic tiering is disk-centric technology rather than memory-only technology, it is sized differently from a pure SAP HANA system. We offer guidelines here, but if you plan to build a production SAP HANA setup including dynamic tiering, we recommend that you contact SAP for expert sizing advice.
With a pure SAP HANA in-memory system, the compute node size is derived from the database size. With disk-backed columnar database technology such as dynamic tiering, the compute node size is established based on the workload on the system – primarily data loading and query tasks. Since dynamic tiering is managing cool/warm data, activity in the dynamic tiering server should be significantly less than that in the SAP HANA server.
For a given SAP HANA system, the size of the dynamic tiering extended store cannot be arbitrarily large compared to the memory size of the SAP HANA system.
There are several functional restrictions of an SAP HANA system with dynamic tiering compared to an SAP HANA system without dynamic tiering. Many of these functional restrictions will be addressed in future releases:
SAP HANA documentation at SAP Help Portal: https://help.sap.com/hana_platform
SAP HANA Dynamic Tiering documentation at SAP Help Portal: https://help.sap.com/hana_options_dt
SAP HANA Dynamic Tiering 2.0 Release Note (SPS 04): https://launchpad.support.sap.com/#/notes/2636634
SAP HANA Dynamic Tiering - Additional Information : https://launchpad.support.sap.com/#/notes/2394124
SAP HANA Dynamic Tiering Support for SAP HANA System Replication : https://launchpad.support.sap.com/#/notes/2767107