HOW TO BACKUP AND RESTORE A DATABASE?

Business requires Database & Database requires Protection

In recent times, data has undergone many challenges. While data storage and management are a growing concern, data security is the most challenging one. Everything comes at the cost and here data security is the cost, we pay in order to step into this world of digitalization. There are a lot of ways that can result in the event of data loss. While hardware failure is the most common cause of data loss, we must not ignore natural disasters too. Furthermore, hard drive theft is another reason of data loss.

Data backup and restoration methods are the only way to ensure contagious data security. Data backups facilitate the safe parking of files or folders on some safe location. There are multiple ways to prepare data backups. Some of the famous backup methods include backups on the hard drive, cloud backup, USB stick backup and backup on the local storage drives or network location. Effective backup management is the prerequisite for efficient data recovery. The system restore method is just a click away and lost data can be recovered and saved in any storage medium.

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    In the business or commercial terms, the database works as the spinal cord of any entity. Every transaction, every business log and every business detail is stored in the company’s database. In this perspective, it won’t be unjust to regard the database as the most crucial digital asset of any entity.

    So, it is imperative to prepare database backup and recovery so as to save databases from any sort of data corruption or loss. By having a backup plan, it will be quite easy to recover the database. Generally, database backups refer to the method where a duplicate of the database information and data is stored on some backup server. It must be noted that a transaction log is also backed up because without them database recovery will be useful.

    Reasons of Database Failure

    There isn’t a pet reason for the database to be lost or damaged. However, there are some of the common reasons for which database backup and recovery plan is required. Following are the prominent ones:

    User Error

    It is one of the prime and biggest reason due to which database may fail. User error is handy enough to corrupt or delete the database. For instance, imagine a situation where the user wasn’t a pro in handling and maintain a database. So, he or she accidentally did something which resulted in database corruption. Now obviously no one wants to leave their crucial databases on the probability of accidental deletion or any other human error. Henceforth, to survive through such user errors, the database needs to be restored point in time.

    Hardware Failure

    It may seem quite absurd in today’s age of hard and fast R&D, but hard drives do get malfunctioned. Usually, the database is stored on the hard drives and there have been incidents where hard drive started to malfunction. Consequently, the user lost his or her crucial database information and data. No one can truly predict the age of a hard drive, henceforth, it is recommended to prepare backup and recovery plans for the database.

    Catastrophic Event

    Although it is the least probable cause of database loss, still nothing should be left on the if and buts. A catastrophic event can be anything such as a flood, an earthquake or anything else which can be counted as unfortunate.

    Out of these catastrophic events, hacking is the leading catastrophic event. Hackers can sabotage the file system by hacking the database. In all of these catastrophic events, either data will be lost or corrupted. This demands an effective backup and recovery plan.

    Types of Database Backups

    Before diving into the brainstorming phase, it is important to know about the appropriate type of backup. Every type has its pros and cons. It depends on the area of application whether pros overtake cons or vice versa. But recently it has been found that multiple backups and recovery approaches can be used together so as to enhance the capabilities of the backup strategy. Such customized backup and restore points have the potential to maximize efficiency and minimize downtime. Following are the common types of database backup:

    Full Backups

    Under the full backup strategy, all files and information on the database will be backed up. This includes all system files, application files, user data or system image to the subjected database. These files will be backed up by making a duplicate copy on the subjected destination such as tape drive, external hard drive or cloud. Afterward, all of the archive bits will be cleared.

    Full backup strategy is considered to be the fastest mode of recovering the database because the complete backup is managed in either the original location or on some safe location. However, this process is time-consuming and in some cases, it was reported that running time exceeded that of the company’s threshold.

    Incremental Backups

    Full backups are time-consuming and hence they are usually run on the weekends. However, incremental backups are handy enough to be run throughout the week. Basically, incremental backups will backup only those data or entries of the database which have been updated since the last full backup.

    Although incremental backup runs faster, still recovery time is a bit complicated. For example, if a full backup is done on Saturday and the data has been changed on Monday, so if anything happens to that data on Tuesday, then in order to restore that data, the user will need to access the Monday’s night backup.

    This complication exists only in case of complete database recovery. However, if any specific segment of the data is to be restored, then it isn’t this much complicated. For the database restoration, the user would need to restore the last full backup including every incremental backup.

    Differential Backups

    It is basically an alternative to incremental backup and is less complicated too. The backup approach is similar to the incremental backup, which only needs updated files since the last full backup. But, it does not clear the archive bits. So, in this way, the data which has been updated since the last full backup will be archived for each time differential backup is run. But once the next full backup is performed, these archive bits will be cleared.

    In this scenario, if the complete database gets corrupted or lost, then the user will need to restore the last full backup along with the latest differential backup. Hence, differential backups are very much less time consuming as compared to incremental backups.

    However, there is one downside of differential backup. Each time differential backup run, backup file tends to get larger and so does the backup time.

    Daily Backups

    Daily Backup is quite an uncommon type of database backups but still, it is used for safeguarding the critical databases. If backup requirements are such that users cannot wait for twenty hours for the complete backup, then daily backups are an ideal choice. Such types of backups are usually running during normal business hours.

    In daily backups, file’s timestamps are used rather than archive bits so as to update the file’s backup. Since the backup will be running during business hours, then too many database files can cast an impact on the speed of the network.

    Database Backup Models

    Although there isn’t any agreed standard for preparing database backups. However, the following four backup models are considered to be the key database backup modules:

    Dump and Sweep

    It is one of the oldest yet common backup model. But still, this backup model is costly in terms of the execution of both primary storage systems and the database backup.

    This method involves the functioning of two distinct features, dump and sweep for the database protection. Here, the database administrator will initiate the dumping of the database to the local storage. Dumping can either be done manually or may be done automatically through automation tools. After this, a copy of the database is created in the form of a single large flat file. DBA can then use this file for the execution of the database recovery when required. Besides that, at some point, a standard file-based backup agent will sweep through the system and write the dumped database over the backup storage medium of the backup server. This process is analogous to sending a package via courier service.

    Traditional Agent Backup

    In this backup model, the company deploys its own backup system consisting of the database server(s). These servers are equipped with the plugin so as to back up the database of this particular environment. This backup model follows appropriate scheduling. These schedules are more guaranteed. For instance, if database backup is scheduled to start at 9 pm, then irrespective of any hindrance, it will definitely start at 9 pm.

    This model equips database administrators with the insight that their backup is recoverable and there exist safe off-platform copies of their database.

    Database Direct Backup

    This backup model follows the modern, modular architectural approach for preparing the database backups. This database backup model does not only involve a database agent, but this model also lets database administrators retain some control over the backup schedules. It must be noted that the database agent can be anyone. It can either be a conventional company’s backup agent or can be any fully decoupled agent like Boost for MS Boost for databases.

    In short, this model rewards database administrators with quick off-platform protection along with more control over the backup schedules. So, it can be said that it is a “best of both worlds” backup strategy.

    Storage Integrated Data Protection

    This backup model is basically like the database direct model but one with the steroids. Storage Integrated Data Protection (SIDP) is not made for daily conventional use. Instead, it is made to deal with exceptional cases. For instance, it is beneficial for such an environment where 100TB of the database is to be backed up on a daily basis. Although this backup model offers a fast database backup process, still a lot of improvements can be made in its transportation process.

    This database backup model employs tightly coupled primary and secondary storage architecture for the backups. However, such coupling does not mean that backup of the mission-critical databases will be quick.

    Database Recovery

    Although an effective backup strategy is a prerequisite for the efficient recovery of the database, it does not mean that only the backup strategy is enough. Instead, recovery methods also need to be handy enough to facilitate streamlined database recovery.

    Following are two basic methods which are being used solely to recover the database:

    Log-based Recovery

    In this recovery method, database transactional logs are saved. This is done so as to recover updated database data, in case it gets failed. For effective recovery, it is necessary that certain database information such as transaction time and nature of the data should be logged on the system.

    Shadow Paging

    In this recovery method, once the transaction is done, its data will be stored in a safe directory for the purpose of safety. This is done to formulate the contingency plan in case of a system crash. Such recovery methods avoid the situation where the system gets crashed in between the transaction. Consequently, any changes made during this phase won’t be reflected in the database.

    Final Note

    With the above literature, it is quite evident that although basics are the same, still there exists a substantial difference between the backup and recovery methods for database and conventional data. On account of the sensitivity of the data, databases are very crucial for the sustainability and security of the business. Owing to such sensitivity, it totally makes sense to formulate a proper backup and recovery strategy for the databases.