What is Oracle Exadata ?
- The Oracle Exadata Database Machine is the only database machine that provides extreme performance for both data warehousing and online transaction processing (OLTP) applications, making it the ideal platform for consolidating onto grids or private clouds.
- It is a complete package of servers, storage, networking, and software that is massively scalable, secure, and redundant.
- Exadata is a bundle of Hardware and Software from Oracle Itself and ready to use immediately.
- Exadata is An Intelligent Storage Server to optimize Database Performance.
- To achieve this intelligence a software called Exadata is installed on all storage servers.
- In a conventional RAC, we need to set up a database machine, storage, and network. On top of that, DBA need to install various database software ASM, and RAC. This involves multiple vendors.
- We have to make sure that each component is compatible with each other and finally compatible with Oracle RAC, ASM and Database Software.
- So this is a very big task. Exadata solves this problem.
Oracle Exadata Architecture
It consists of a Database server, storage server, InfiniBand switches used for intra-system servers to server communication, Administrative Ethernet switch for remote management
Oracle Exadata Database Servers or Compute Nodes
(1)It is a System that includes all the hardware necessary to run the Oracle Database
(2)Database Servers Run Linux or Solaris and Oracle Database software
(3) Perform complex database processing such as joins, aggregation, etc.
Oracle Exadata Storage Servers or Cell servers
(1) It’s another storage device, which has CPU, Memory, Disk, network cards, an Operating System Oracle Linux and Most importantly part Exdata Storage Server Software.
(2)Search tables and indexes filtering out data not relevant to a query
(3)Cells serve data to multiple databases enabling OLTP and consolidation
(4)Simplicity, and robustness of storage appliance
There are mainly three services that run on cell servers for processing, CellSRV (Cell Service), MS (Management Server) and RS (Restart Server).It has three components
(1) CELLSRV, the cell service: CELLSRV handles the actual I/O processing of the storage server.
It is not uncommon to see heavy usage from CELLSRV process threads during periods of heavy load.
CELLSRV provides Communication with database nodes using the iDB/RDS protocols over the InfiniBand network, Disk I/O with the underlying cell disks, Offload of SQL processing from database nodes,I/O resource management, prioritizing I/O requests based on a defined policy
(2)Management Server (MS): MS service provides an interface to DBA for communicating or Managing Cell servers. CellCLI is the Command Line tool that Exadata DBA uses for performing Exadata Administration services. MS is written in Java, unlike the other background processes which are distributed in binary form and are likely written in C.
(3) Restart Server (RS): This service is to ensure the functioning of the Exadata Server. RS monitors CellSRV and MS for liveliness and restarts them whenever required.
RS, the restart service. Performing a similar role to SMON, RS monitors other processes and automatically restarts them if they fail unexpectedly.
RS also handles planned restarts in conjunction with software updates.
The main cellrssrm process spawns several helper processes, including cellrsbmt, cellrsbkm, cellrsomt, and cellrsssmt.
Most Useful Features of Oracle Exadata
(1) Exadata Smart Scans – Oracle Exadata architecture offers a 10X or greater reduction in data sent to database servers
Suppose a simple query Select * from jtf_notes where jtt_type=’EXACT’ which returns only 10,0000 is executed on the database machine and the jtf_notes table has 1000 Million rows. So, in that case whole 1000 Million rows will come from the Storage server to the DB node for processing and after processing by the DB node DBA will get query output. This whole process takes a lot of time and resources from all RAC components. Exadata smart scan returns only the 10,0000 rows to the database server. DBA can easily estimate the impact of this change. Technically this term is called as Exadata Smart Scan.
init ora parameter Cell_offload_processing controls
The default setting is true. We can manipulate it to find out if the smart scan is causing any issue
(2) Exadata Storage Indexes – Eliminate unnecessary I/Os. Storage cells keep track of maximum and minimum values stored in different areas and use those values to determine where predicates can not exist. This allows the storage cell to not have to read the area at all thus saving time and processing cycles.
(3) Hybrid Columnar Compression – Oracle Exadata architecture offers Efficient compression that increases effective storage capacity and increases user data scan bandwidths by a factor of up to 10X
(4) Exadata Smart Flash Cache – Oracle Exadata architecture Breaks random I/O bottleneck by increasing IOPs by up to 20X; Doubles user data scan bandwidths
(5) I/O Resource Manager (IORM) – Oracle Exadata architecture Enables storage grid by prioritizing I/Os to ensure predictable performance
(6) InfiniBand Network: Exadata uses a high-speed InfiniBand network to connect database servers and storage cells. This network provides a fast and reliable communication layer.
(7) Exadata Software: The platform runs a specific version of the Oracle Database software, optimized for the Exadata hardware. It includes various optimizations and features unique to the Exadata platform.
(8) Scalability and Redundancy: Exadata is highly scalable, allowing more database and storage servers to be added as needed. It also includes features for high availability and data protection, like redundant hardware components and Oracle Real Application Clusters (RAC) support.
Cell Check and shutdown/startup commands:
Note: For full list of commands use: cellcli -e help cellcli -e alter cell shutdown services all cellcli -e alter cell startup services all cellcli -e alter cell shutdown services cellsrv cellcli -e alter cell restart services cellsrv cellcli -e list lun detail cellcli -e list griddisk detail cellcli -e list celldisk detail cellcli -e list physicaldisk detail cellcli -e list flashcache detail cellcli -e list physicaldisk attributes name, diskType, luns, status cellcli -e list physicaldisk where disktype=harddisk attributes physicalfirmware cellcli -e list lun attributes name, diskType, isSystemLun, status imagehistory (root/sudo) imageinfo (root/sudo) service celld status (root/sudo) lsscsi | grep MARVELL
Cell related Database views:
select * from sys.GV_$CELL_STATE; select * from sys.GV_$CELL; select * from sys.GV_$CELL_THREAD_HISTORY; select * from sys.GV_$CELL_REQUEST_TOTALS; select * from sys.GV_$CELL_CONFIG;
ExaCS and ExaCC
Exadata Cloud Service (ExaCS) and Exadata Cloud at Customer (ExaCC) are two cloud-based offerings from Oracle that utilize the Exadata platform. Each offers the high performance of Exadata with the flexibility and benefits of a cloud deployment, but they are designed for different use cases and environments.
Exadata Cloud Service (ExaCS)
ExaCS is Oracle’s Exadata offering in the public cloud. It is hosted, managed, and maintained by Oracle in its cloud data centres. ExaCS provides the full power of the Exadata database machine combined with the benefits of a public cloud environment.
Key Features:
(1)Public Cloud Deployment: ExaCS is available in Oracle Cloud Infrastructure (OCI), providing easy access and integration with other OCI services.
(2)Managed Service: Oracle manages and maintains the Exadata infrastructure, including hardware, networking, and software.
(3) Elastic Resources: Customers can scale resources (CPU, storage, etc.) up or down based on their requirements.
(4) Pay-as-you-go Pricing: Flexible pricing models based on usage.
Use Cases:
Ideal for businesses looking to migrate on-premises Oracle databases to the cloud.
Suitable for organizations seeking the performance of Exadata without the complexity of managing physical hardware.
Exadata Cloud at Customer (ExaCC)
ExaCC brings the Exadata Cloud Service to the customer’s own data centre. It is designed for organizations that need to keep their data on-premises due to regulatory, latency, or other business requirements.
Key Features:
(1)On-premises Deployment: The Exadata infrastructure is installed in the customer’s data centre but is managed remotely by Oracle.
(2)Cloud Benefits with Data Residency: Offers the flexibility and elasticity of cloud computing while keeping data within the customer’s data centre.
(3)Oracle Managed: Oracle manages the Exadata hardware and software, even though it resides in the customer’s facility.
(4) Subscription Model: Customers subscribe to ExaCC, avoiding the upfront capital expense of purchasing Exadata hardware.
Use Cases:
Suitable for organizations with strict data residency requirements.
Ideal for businesses that require cloud flexibility but face constraints in moving their data to a public cloud.
Summary
- Exadata is often used in environments that require high performance for large databases, such as data warehousing, OLTP (Online Transaction Processing), and mixed database workloads. It’s known for its ability to deliver fast performance, scalability, and reliability for Oracle Database environments.
- With Oracle Exadata Database Machine, customers can reduce IT costs through consolidation, manage more data on multiple compression tiers, improve the performance of all applications, and make better business decisions in real-time
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