From: Sybase Website
Foreword: For current business systems, maintaining the availability of the system and the continuity of running business become more important, many systems require 7x24 hours to run completely online. Whether there are some potential possible failures such as disk failure, processor failure, power failure, network failure or planned downtime maintenance, all constitute different levels of threats to system availability and business continuity. When the system is stopped, the company's loss is more than just some tangible assets such as money, hardware, etc., and more important is to lose intangible assets, such as customer and partners loyalty and trust.
For the user, in the operation of its business system, on the one hand, it is necessary to prevent data loss, and on the other hand, the maximum data availability must be guaranteed. Therefore, it is very important to develop a business recovery and continuity. Thus, a spare system is created. When the production system fails, the standby system can be recovered using the standby system, so that the minimum business parking time will become a problem that the user must consider. Since many business systems are based on the database, the importance of database backup is not allowed.
The world's largest automatic network storage solution provider EMC provides users with excellent database backup mode with its industry leading technology. Due to the inherent advantages of EMC storage, it has a certain increase in the performance, scalability, manageability of the database, which is more than the traditional manner. The following uses the Sybase database backup as an example, introducing the high-quality backup job implemented by the EMC Storage.
Type 1 of database backups, cold backing is usually backed up by regular production system databases and stores backup data on tapes, magnetic disks. The backup data is usually in a non-activated state until the fault is caused to activate when the production database system unit is available. The timeliness of the cold backup depends on the most recent database backup. The cycle of the database cooling is generally longer.
2, the implementation of the hot standby hot standby usually requires an alternate database system. It is similar to the cold back, but only when the production database fails, it can be recovered by the data of the alternate database. Therefore, the recovery time of hot spare is largely shortened than the cold. Many hot spare are implemented by continuously loading logs of production databases into backup databases. The timeliness of hot spare data also depends on the most recent database backup.
3. Hot Standby is fully hot and standing is the highest level of database backup method. Fully hot standby needs a backup database system that is active as the production database. And the production database is in a fully synchronized state with the backup database system, all modifications to the production database are also implemented on the backup database. Implementation of full hot standby usually requires complex hardware and software technology, so its recovery requires a higher price relative to the cold and hot spare. But at the same time, it also has the shortest recovery time, which is especially important for some important business systems.
Traditional Sybase Database Backup Method 1, Database Realization Method The traditional database cooling method is to use the Dump Database command when the Sybase database is started, backed up the database to the specified disk or tape device. When the production system fails, use the Load Database command to disk or tape data recovery system.
Although the method of cold off is simple, it has a large difficulty implementation. Because all running online services must be paused when the database backup is running, the database backup is very large, and a large number of processor resources are required. Therefore, many database cooling have taken some ways, such as temporarily stopping the service at less business, starting the database in a single user manner, and performs backup, and then restores the business system after the backup is completed.
The disadvantage of the cold, is to consume a large number of processor resources, so other applications on the host are more affected. In addition, due to the current availability requirements of the business system, the backup window is getting smaller and smaller, which brings great challenges to the implementation of the cold. 2. Database hot standby implementation of the Sybase database is generally implemented by Sybase's replication server products, and many other database products also provide similar techniques.
Using the hot spare of the replication server to maintain a pair of database servers, the two databases are activated and in the replication system, as a whole, one of which is a backup of another database. Client applications typically modify the primary database, copy the server to read the master database log through the LTM, and constantly implement the logs of logs on the backup database through the LAN or WAN. If the channel conditions are good, the primary database and the replication database are almost completely synchronized, but it is accurately that replication technology is still a asynchronous technology.
Hot spares achieved by copying technology are a successful technology, which is working very well in some specific systems. But it also has some shortcomings. The first is that it needs to occupy network bandwidth, which is no problem in the case of change in the main database data, and when the data changes, it will affect other network applications. This problem can be alleviated by establishing a proprietary replication network. Another problem is that the replication system still needs to consume the host's processor resources, and affect the production system, although this effect is much smaller than the cold back.
The Sybase database backup implemented by EMC storage technology implements the Sybase database backup using EMC storage technology, avoiding the deficiencies of the above-mentioned traditional backup mode. For the user, EMC's innovation in database backup technology has brought different feelings.
1. An important software product that applies its high-end storage Symmetrix is applied in the backup method of the Timefinder software EMC: TimeFinder. EMC Timefinder software is a business continuity solution. Its work mode is to create multiple interrelated, accessible online business continuity volumes (BCV), and BCVs are EMC storage devices with special attributes, independently support host applications and processes independently.
EMC TimeFinder's unique feature helps maintain security in changing, and ensure that business applications use the required data. BCV establishes a mirror volume of the event production volume, which can perform multiple simultaneous information system tasks in parallel, while the main volume remains performing normal Symmetrix I / O operations from the original host / server.
2, the implementation method of the database cooling uses the EMC's TIMEFINDER, and the cool back of the database can be described as a light. The usual standard volume and the BCV volume are in synchronous state. When using BCV, simply separate the standard volume with the BCV volume and make the BCV volume visible for the host, and then subsequent processing can be performed.
The advantage of using Timefinder to achieve database cooling is that there is no impact on the production database. Since synchronization between the production volume and the BCV volume is implemented within the storage, the processor resources do not consume the host, because the storage system typically has internal high-speed channels and large-capacity memory buffers, the efficiency of achieving greatly improved. Another significant feature is the unrelated feature of the application, and therefore, in addition to the Sybase database system, this implementation of TimeFinder is equally applicable to other databases such as Oracle, Informix, etc. In addition, TimeFinder technology is not limited to database systems, but also the same applicable for file systems. And this is the limitations of some database replication software.
3, the implementation of the database hot standby uses the Sybase database hot standby using the EMC storage technology to use two new features of the Sybase 12.5: Quiesce Database Enhancement Options for External Dump and DataServer's -Q boot options.
The Quiesce Database for External Dump Command can keep the silent database in a consistent state, so that the separated database is copied in a consistent production database, and the log is not interrupted and synchronized on the backup database, Thus the purpose of the database hot standby. This command replaces the Dump Database command to form an initial database backup, lay the foundation for the subsequent implementation database log. And due to the generation of database backups, the network bandwidth and host processor resources are saved by storing their own implementation.
The DataServer's -q option is used to distinguish the production database and backup database, which is applied only on the backup database. When you start the backup database with the DataServer-q option, the BCV volumes separated in the External Dump state can be restored to an available database backup, and the database log can be implemented on this database.
Although the use of TIMEFinder implementation of database hot standby is the same, the principle of using replication servers is not the same, but the idea is quite similar, which is constantly loaded on the backup database to the backup database. At the same time, using EMC storage itself, it is easy to obtain database backup and database, and saves network bandwidth and host processor resources, and does not affect the production host.
In addition, the remote image of the production database can be implemented using the other functional software SRDF stored in the EMC storage, which can be implemented with disaster backup. SRDF has multiple ways such as synchronization, asynchronous, in a more important application, can use SRDF synchronization mode, and then supplemented by some software tools, you can reach a full database fever with remote carrier function. You can also combine SRDF with TimeFinder to realize the multi HOP hot standby of the database, providing a richer data backup mode.
Because of the space limit, only one piece of EMC in the backup job is mentioned. In fact, the EMC data manager provides a complete software, hardware and service integrated solutions, leading performance and functionality, especially for super-large database tape backup and restoration, and ensures enterprise applications. , The maximum efficiency of information technology resources and online business processes. The backup scheme provided by EMC can complete the backup job quickly and frequently, and does not cause any interruption; avoid multiple copy operations, shorten the batch time; load or refresh the data warehouse as needed; and maximize online Treatment time. This quality solution provided by EMC in backup work will bring more practical value for users.
