High Availability Systems



Open Technologies offers solutions on creation of high availability systems based on Oracle technologies ensuring enterprise information systems operation continuity.

One of the main factors defining effective operation of business of the today's companies is uninterruptible operation of services provided by corporate informations systems (CIS). Downtime of CIS supporting the enterprise business caused by equipment failure, software failure, errors of the personnel or low communication quality can lead to serious losses and sometimes business interruption.

As a rule, continuous operation of state-of-the-art information systems is based on uninterruptible work of database. Open Technologies offers solutions based on Oracle Real Application Clusters (RAC) technology ensuring high availability of corporate database. Oracle RAC ensures operation of the unified database at several servers, allows control of load and flexible scaling of the system. Oracle RAC technology operates almost at any hardware platform and with all applications.

High availability systems are aimed to solve the following tasks:

Increased availability. Oracle RAC excludes situation when failure of server or its software leads to failure of the whole system. In case of DBMS instance failure or whole node failure the database remains open and users or application continue their work via other operating instances which, as compared to conventional high availability systems, ensure higher service availability level.

Increased scaling. With growth of requirements to resources Oracle RAC allows adding new nodes to cluster without need to stop applications. This way you can gradually build up total capacity of cluster system by adding new nodes. For this, standard cheap servers are more economically efficient as far as the cost of the cluster hardware can be times less than the cost of large SMP server of equivalent capacity. New facilities can be used immediately after their connection.

The main possibilities of Oracle RAC:

Possibility of parallel query processing. Parallel Query Option technology allows involving several clusters to process one query.

Application notification mechanism. Fast Application Notification (FAN) technology ensures notification of application about any change of cluster state which allows more effective consideration of the system state and use of its resources.

Independence from additional software. Oracle Clusterware provides all possibilities required for Oracle RAC operation including accounting of nodes, message and blocking service. Cluster software has unified interface and unified functionality for all Oracle compatible platforms. Oracle RAC can work jointly and with additional cluster software of other manufacturers but, with due account of Oracle Clusterware functions, there is no need to purchase and use cluster software of other manufacturers.

High availability of applications produced by other manufacturers. Oracle Clusterware is a multiplatform software allowing joining separate servers into unified cluster system. Oracle Clusterware provides all possibilities of cluster infrastructure ensuring high availability of applications produced by other manufacturers.

Operative update of software versions. Software update is made with system operating.

User session transmission. Transparent Application Failover (TAF) technology ensures transparent transfer of user sessions to Oracle RAC cluster nodes in case of database instance failure. At this, if at the moment of node failure some transaction was under way it shall be executed once again by initiating application after failover to another node. This technology allows applications to conceal cluster component failures from users.

Support of various file systems. Data storage can be provided by Oracle Automatic Storage Manager (ASM), Oracle Cluster File System, NFS file system provided by Network Attached Storage (NAS), raw devices and cluster file systems by other manufacturers.

Infiniband technology support. Use of Infiniband technology in Oracle RAC to organize internode connection ensures even higher performance and possibility of horizontal scaling. Reliable Datagram Sockets (RDS) protocol support for Infiniband guarantees high bandwidth, low delay level, highly reliable interprocess cooperation (IPC) and, at the same time, reduces load of computing subsystem and input-output subsystem.

Transparency. Oracle RAC for users and applications looks like database with sole instance. Easy to operate. Operations on setting and adjustment of database instance at one node can be automatically expanded to other nodes.

Load distribution. Oracle Real Application Clusters has load control technology which ensures the highest possible application performance. Upon creation of new user sessions Oracle RAC chooses the least loaded cluster node and distributes load evenly at all nodes.