The Oracle Database Appliance is a family of engineered systems which are designed to be database servers. These Linux x8664 based systems are simple, affordable and optimized for database workloads. These engineered systems are a combination of hardware and software with certified configurations. By using certified configurations, customers can focus on using optimized systems rather than trying to figure out how to build and optimize a combination of CPUs, memory, storage devices, networking, operating systems, file systems and databases.
The Oracle Database Appliance has three different models:
The Oracle Database Appliance X8-2S is an entry level x8664 server with a 2U form factor and a single CPU socket which is ideal for small, single instance Oracle databases. It has 192-384 GB of RAM, uses 12.8 TB of NVMe flash for high performance storage and either 10/25 GbE SFP28 or 10GBase-T networking ports.
The Oracle Database Appliance X8-2M is a mid market, x8664 server with a 2U form factor and two CPU sockets which is ideal for single instance Oracle databases. It has 384-768 GB of RAM, up to 76.8 TB of NVMe flash for high performance storage and either 10/25 GbE SFP28 or 10GBase-T networking ports.
The Oracle Database Appliance X8-2-HA is a two node, x8664, high availability solution. Each node has a 2U form factor. There is a 4U shared storage unit to give a combined form factor of 8U [2+2+4].
Each node has two CPU sockets, 768-1536 GB of RAM, two SSDs for local storage [for OS and DB software] and either 10/25 GbE SFP28 or 10GBase-T networking ports. There is a dedicated 25 GbE SFP28 card for cluster communication and the shared SAS storage. The shared storage has 46-184 TB of storage using 6-24 SSDs. You can also use HDDs for up to 252 TB of storage.The Oracle Database Appliance X8-2-HA is a great platform for a simple to use, fully redundant, two node Oracle Real Application Cluster [RAC].
When the Oracle Database Appliance X8-2-HA is used as a two node RAC cluster, it uses Oracle Clusterware as the cluster manager. To minimize IO contention and maximize IO performance when using a set of storage devices, both single instance and RAC databases should use Oracle Advanced Storage Management [ASM] as the volume manager. ASM also supports a general purpose POSIX, shared cluster file system called ASM Cluster File System [ACFS]. ACFS enables non Oracle Database applications to read/write files in shared file systems. Oracle Grid Infrastructure is software which consists of Oracle Clusterware, Advanced Storage Management, ASM Cluster File System and ASM Dynamic Volume Manager.
The Oracle Database Appliance engineered systems were designed to run either single instance or clustered (Real Application Cluster) Oracle Databases. The hardware and software used on the Oracle Database Appliance is also a great platform to run either single instance or clustered (Scaleout) Oracle TimesTen In-Memory Databases.
The TimesTen In-Memory Database is a SQL RDBMS which supports ACID transactions and persists data in a file system. As TimesTen is an in-memory database, all of the data is in memory all of the time. Having the data in memory all of the time enables very low latency for SQL operations. For example, a simple SQL select statement by primary key is possible in under two microseconds. The time taken to perform an operation depends on many factors. Selecting a row with 999 CLOB columns, returning a resultset of millions or rows or doing a 20 table join will all tend to take longer than two microseconds.
TimesTen uses a subset of the SQL and PLSQL used by the Oracle Database. TimesTen also supports OCI and ODPI-C based Oracle APIs.
TimesTen can be used as either a system of record or as a read/write cache for an Oracle Database, RAC or Exadata [220.127.116.11 - 19c]. Some TimesTen production customers use TimesTen as a system of record and others use TimesTen as a read only and/or read/write cache to their Oracle Database.
TimesTen comes in two flavors, TimesTen Classic and TimesTen Scaleout. TimesTen Classic uses a set of single instance databases using replication for high availability. TimesTen Scaleout is a clustered/sharded database that appears to have single database image for SQL applications.
Oracle TimesTen Classic supports Oracle Clusterware as a cluster manager. Oracle Clusterware is used with TimesTen Replication for things like death detection & restart, fail-over and switch-over. TimesTen Replication does not require shared storage. Oracle Clusterware requires shared storage. Oracle Clusterware is not used to manage TimesTen Scaleout.
TimesTen Scaleout has a shared nothing architecture so shared storage is not required. TimesTen Scaleout 18.1 consists of a set of up to 64 database nodes. These database nodes each need local CPU, memory, networking and either local or remote storage.
The Oracle Database Appliance X8-2S or X8-2M are well suited to be 'database nodes' in a TimesTen Scaleout cluster. These ODA appliances come pre-configured with Oracle Linux, fast CPUs, fast networking, fast storage and plenty of memory. When using these ODA as database nodes for TimesTen Scaleout, Oracle Grid Infrastructure is optional:
Having a set of known, engineered systems simplifies deployment and maintenance for large TimesTen Scaleout clusters.
The Oracle Database Appliance X8-2-HA is a two node engineered system with shared storage. This ODA configuration enables the simplest TimesTen Replication configuration, ie an Active Standby Pair managed by Oracle Clusterware.
TimesTen Replication occurs between the two ODA nodes using their dedicated 25 GbE network.
Both the TimesTen Active and Standby databases have their own 'dedicated' ACFS file systems using the shared storage.
Disclaimer: These are my personal thoughts and do not represent Oracle's official viewpoint in any way, shape, or form.