Linux server cluster system implementation solution-Linux Enterprise Application-Linux server application information, the following is a detailed description.
I. Basic concepts of clusters
There is a common way to greatly improve the security of the server, which is the cluster.
The Cluster technology can be defined as follows: a group of independent servers act as a single system in the network and are managed in a single system mode. This single system provides high reliability services for the customer workstation.
In most modes, all the computers in the cluster share a common name. services running on any system in the cluster can be used by all network customers. The Cluster must be able to coordinate and manage the errors and failures of the separated components, and add components to the Cluster transparently.
A Cluster contains multiple (at least two) servers with shared data storage space. When any server runs an application, application data is stored in the shared data space. The Operating System and Application Files of each server are stored in their local storage space.
Each node server in the Cluster communicates with each other through an internal LAN. When a node server fails, the applications running on this server will be automatically taken over on another node server. When an application service fails, the application service will be restarted or taken over by another server. When any of the above faults occurs, the customer will be able to quickly connect to the new application service.
Ii. Cluster hardware configuration
Backup storage
In a cluster, the dual-host backup storage system is the simplest and cheapest solution for hardware configuration. Generally, the hardware configuration of the backup storage service requires two servers, each server has an independent operating system hard disk and data storage hard disk. Each server has a network card connected to the client, and a pair of mirror cards or network cards that complete the image function.
The backup storage has many advantages, such as simple configuration, easy to use, and low price. However, the backup storage must use network-based backup storage to synchronize data, therefore, the CPU and memory resources of the network server need to be occupied. The performance of the backup storage is lower than that of a single server.
Some image server cluster systems use the memory image technology. The advantage of this technology is that all applications and network operating systems synchronize images on the two servers. When the host fails, the backup machine can take over all applications with almost no feeling. Because the memory of the two servers is completely the same, but when the system application program has a defect that causes the system to go down, the two servers will go down simultaneously. This is also the memory image card or network card for data synchronization. In the process of reading and writing large data volumes, the two servers may not synchronize data in some statuses, therefore, the backup storage is suitable for users with low budget and low requirements on Cluster Systems.
Hardware configuration example:
Network server, two operating system disks
Server Data Storage hard disk depends on user needs
Server image card (some software can use standard Nic)
Two network service NICs
Iii. Dual-host and disk array
Compared with the dual-host system of the backup storage, the interconnection structure between the dual-host and the disk array is larger than that of the third-party disk array cabinet. Currently, many companies such as haowei and Jingye produce disk array cabinets, the disk array control card is installed in the disk array cabinet. The array cabinet can directly configure the hard disk in the Cabinet as a logical disk array. The disk array cabinet is connected to a common scsicard on the server through the SCSI cable. The system administrator must directly configure the disk array on the cabinet.
The interconnection structure between the dual-host and the disk array does not use the memory image technology, so a certain switching time is required (usually 60? D? D180 seconds), it can avoid all system downtime due to application defects, and because all data is stored in the middle disk array, when the working machine fails, the backup machine takes over the working machine and reads data from the disk array. Therefore, data is not synchronized because this solution does not require network image synchronization, therefore, the performance of this cluster solution server is much higher than that of the backup storage.
The disadvantage of the dual-host and disk array interconnection structure is that there is a single point of failure in the system. The so-called single point of failure refers to when a part or an application in the system fails, all systems are down. In this system, a disk array causes a single point of failure. When a logical or physical fault occurs in the disk array, all the stored data is lost. Therefore, when selecting this solution, select a product with good quality and after-sales services.
Hardware configuration example:
Two network servers
Two server operating system hard disks
One third-party disk array Cabinet
Two dedicated SCSI wires for the cabinet
Disk Array cabinet data storage hard disk determined by user requirements
Two network service NICs
In addition, some vendors also have better technical solutions, such as HP.
Iv. HP dual-host dual-controller Fault Tolerance System
HP NetServer provides a high quality and highly reliable hardware foundation for dual-host dual-controller fault tolerance systems ......
The HP dual-host dual-controller fault tolerance system combines the security and reliability of HP Server products with the advantages of Cluster technology, and cooperates with each other to provide the advantages of both.
Hardware configuration example:
Two network servers of the hp l System
Two server operating system hard disks
One HP hard disk storage cabinet (SS/6, RS/8, RS/12)
Dedicated SCSI cluster adapter cable for Cabinet
Cabinet data storage hard disk determined based on user requirements
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