Q: Why do you usually choose to implement SAP?
Because sap has so many advantages to others, like:-
1. Sap is componentized (summation of modules).
2. Software & hardware independent.
3. R/3 architecture.
4. Own programming Language (abap) 4-generation.
5. Supports at different level are also.
6. Sap is able to fit easily into any size of company.
Q: What is a "High Availability Cluster"?
The aim of a High Availability Cluster (HAC) is to provide the availability of specific services within a system landscape. This is reached by reducing downtimes using redundant cluster nodes. A common HAC setup consists of two cluster nodes, which is the minimum for redundancy. If one server node crashes, the second node takes over the clustered services and secures the availability this way. This is also called a "two-node cluster" or a "failover cluster." According to the demands of availability, the number of server nodes can be increased to minimize the risks of failure of a node.
Q: What is "switchover"?
Switchover is referred to as a planned switchover of a primary server to a standby server, which means without a failure of the primary server. A switchover is always initiated by the system administrator.
Q: What is "fallback"?
Fallback is referred to the process of switching back from a secondary server node to the primary server node after a failover occurred and the primary server node is available again. A fallback can be done automatically by the cluster software or intelligent, which means manual by the system administrator.
Q: What does "virtualization" mean?
The term virtualization in the context of HA refers to a kind of abstraction performed by the cluster software. The software creates a virtual host that owns a virtual hostname, virtual disk, and so on. Virtual in that manner means that such resources cannot only be owned by one physical machine but by all of them. Which node currently owns or runs a resource is managed by the cluster software. Related resources are usually grouped to logical containers (for example Groups on MSCS or packages on HPSG) that can perform failovers independently.
Q: What is ASCS/SCS?
With SAP NetWeaver 04 Java, the Message Server and the Enqueue Server are separated from the Central Instance. These two services are grouped within the SAP Central Services Instance (SCS) as services. From NW04s the ABAP Central Services can be also separated from the Central Instance. Each stack, ABAP and Java, has its own Message Service and Enqueue Service. For
ABAP systems the Central Services are referred to as ASCS, for Java systems the Central Services are referred to as SCS. The ASCS and the SCS are leveled as SPOF and require a High Availability Setup therefore. If the ASCS is integrated within the ABAP Central Instance (standard in Net Weaver 04) the Central Instance of the ABAP system needs a HA setup also.
Because sap has so many advantages to others, like:-
1. Sap is componentized (summation of modules).
2. Software & hardware independent.
3. R/3 architecture.
4. Own programming Language (abap) 4-generation.
5. Supports at different level are also.
6. Sap is able to fit easily into any size of company.
Q: What is a "High Availability Cluster"?
The aim of a High Availability Cluster (HAC) is to provide the availability of specific services within a system landscape. This is reached by reducing downtimes using redundant cluster nodes. A common HAC setup consists of two cluster nodes, which is the minimum for redundancy. If one server node crashes, the second node takes over the clustered services and secures the availability this way. This is also called a "two-node cluster" or a "failover cluster." According to the demands of availability, the number of server nodes can be increased to minimize the risks of failure of a node.
Q: What is "switchover"?
Switchover is referred to as a planned switchover of a primary server to a standby server, which means without a failure of the primary server. A switchover is always initiated by the system administrator.
Q: What is "fallback"?
Fallback is referred to the process of switching back from a secondary server node to the primary server node after a failover occurred and the primary server node is available again. A fallback can be done automatically by the cluster software or intelligent, which means manual by the system administrator.
Q: What does "virtualization" mean?
The term virtualization in the context of HA refers to a kind of abstraction performed by the cluster software. The software creates a virtual host that owns a virtual hostname, virtual disk, and so on. Virtual in that manner means that such resources cannot only be owned by one physical machine but by all of them. Which node currently owns or runs a resource is managed by the cluster software. Related resources are usually grouped to logical containers (for example Groups on MSCS or packages on HPSG) that can perform failovers independently.
Q: What is ASCS/SCS?
With SAP NetWeaver 04 Java, the Message Server and the Enqueue Server are separated from the Central Instance. These two services are grouped within the SAP Central Services Instance (SCS) as services. From NW04s the ABAP Central Services can be also separated from the Central Instance. Each stack, ABAP and Java, has its own Message Service and Enqueue Service. For
ABAP systems the Central Services are referred to as ASCS, for Java systems the Central Services are referred to as SCS. The ASCS and the SCS are leveled as SPOF and require a High Availability Setup therefore. If the ASCS is integrated within the ABAP Central Instance (standard in Net Weaver 04) the Central Instance of the ABAP system needs a HA setup also.
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