AsBase® DataGuard Suite
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The problem of data safekeeping and system availability
Almost any information system today (whether it is a banking system, a ticket selling system or an online shop) contains a database (DB). The DB is exactly the “place” where all the data required for correct functioning of a system is stored. For example, in a case of banking system this information consists of clients’ accounts, transactions, debit and credit card processing. In a case of online shop these are article data, product information, stock, prices, orders, etc. It’s obviously, that DB failure may lead to significant consequences, which in turn will lead to considerable loss of profit. In fact ones desire to minimize these failures is quite obvious too.
Solution 1 – Backup and Recovery of the DB
One of the ways to consider solving this task may be creation and periodical update of backup copies of the DB – a special set of files, which contain all the information stored in the DB at a specified point in time. Backup copies can be stored on a separate disk or even on a separate server, running at a remote location. In case of DB failure all the data could be recovered from backup copy and the system will continue to run.
This way, however, has two substantial drawbacks.
Drawback 1 – it is impossible to recover absolutely all data.
As backups are created over certain periods of time, there is always some amount of data, that will be impossible to recover from backup. And in many cases the value of this data is very high, because it contains information about recent operations performed in the system. Let’s consider an example with online retailer. DB backup is performed each Monday. In that case, if the failure occur on Wednesday it will be possible to recover only the data that was saved with the latest backup, in our case as of Monday. Of course, at the same time, all the information about orders placed from Monday till Wednesday will be lost. Clients who will not receive their orders in time will definitely be disappointed. And our retailer will lose not only money but also its reputation of reliable sales partner.
Even if backup procedure is performed more frequently, daily of even hourly, there will be always a portion of data impossible to recover in case of unpredicted failure.
Drawback 2 – the process of BD recovery consumes significant time..
Procedures involved in DB recovery from backup may take significant time – it depends on the scale of the failure and the volume of data that has to be recovered, and ranges from several hours to days. While the recovery process is active the system itself cannot serve its customers or clients. Let’s go back to the online retailer. In addition to the orders lost as a result of the failure itself, the shop would be unable to take new orders for several more hours, and as a consequence, there would be additional financial and reputational loses.
Solution 2 – Synchronous data replication
This solution is found to assure complete data recovery and ensures minimal system downtime.
100% data safety
In addition to a main server that is hosting DB, several additional (standby) servers are set up. Each of these servers contains an exact copy of the original DB, and they are linked together using special synchronous data replication software. The gist of all this mechanism is that all the operations performed on the main server are automatically replayed (replicated) on standby servers. This process is called synchronous because no operation on main DB is considered completed until it is successfully applied to standby servers. That’s why it is possible to assure safety of all the data. In the example with online retailer no already placed orders would be lost, as the standby database contains all the data about all orders clients have managed to place before the failure.
Minimized downtime of DB
But what one should do, if the failure did occur? The most plain and straightforward way is to let the database administrator possibility to substitute the failed DB with a copy, deployed on one of standby servers. Speaking technically to make it possible for the administrator to switch roles of replication nodes – the node (server) initially acted as standby, may be switched to act as primary, using simple command issued by administrator, and will continue to serve clients’ requests starting from the point when the failed node stopped. Such procedure takes about 2-3 minutes to complete, there is only one prerequisite – the administrator should be able to receive event message from the system and can issue the command.
Consider a situation, that DB administrator is out of office and unable to perform duties remotely. Downtime value per minute is quite high. In such situations automatic role switching feature is really helpful. If this feature is enabled the system would be able to identify failure itself and would switch the database. Users may not even notice the DB momentarily became unavailability.
AsBase DataGuard Suite – easonably priced data safety and availability
Having considerable experience in developing complex multitier IT projects developers of AsBase Dataguard Suite are aware of high importance of the problems discussed above and necessity of solving them. At the same time, it is obvious that currently available solutions supplied by database management systems manufacturers all over the world, such as Oracle, have one major drawback – extremely high price.
Thus, Oracle DataGuard Broker, which provides synchronous data replication and automatic node switchover features, is available only as a part of Oracle Database Enterprise Edition, and its price is expressed in tens of thousands of US dollars.
Not all customers can afford such software investments. At the same time DB fault protection and data safety become more important, and even greater quantity of organizations are in high demand for such solutions. Herewith many companies use cheaper or even free solutions from Oracle – Oracle Standard Edition and Oracle Express Edition respectively.
Having analyzed the above circumstances Corside Group has come to a decision to develop its own solution – AsBase DataGuard Suite.
AsBase DataGuard Suite is almost complete replacement of Oracle DataGuard Broker and it provides the following major features:
The usage of AsBase DataGuard Suite in conjunction with Oracle Database provides nearly 100% data safety and 24 hour a day availability of the database to client software.
Convenient and intuitive installation and replication network configuration tools are already included in AsBase DataGuard Suite, as well as command line utility that in many respects analogous to the corresponding utility from Oracle. This last circumstance makes AsBase DataGuard Suite easy to use by database administrators familiar with Oracle products.
In addition to these advantages, AsBase DataGuard Suite has another one – the price is tens time lower (compared with Oracle’s solutions).
