How often a database should be backed up depends on how often its contents is modified and how important the contents is. A frequently modified database containing business critical information might be backed up several times a day. On the other hand, a database that is rarely modified, but is used for reference, might be backed up once a week or even once a month.
Backups that were made before the application of FileVault will not be encrypted. Backups made after the application of FileVault might be encrypted depending on how the backups were made.
backup
backup
Relational Database
All users should be able to access same data.A user's view is immune to changes made in other views.Users should not need to know physical database storage details.DBA should be able to change database storage structures without affecting the users' views.Internal structure of database should be unaffected by changes to physical aspects of storage.DBA should be able to change conceptual structure of database without affecting all users.
Files should be archived as often as possible. Backup programs (of which there are many to choose from) are used to create archives. Backups can be made to a variety of storage mediums including removable drives and optical discs (CD, DVD or BluRay). Removable drives are the best option in terms of storage capacity and speed and they allow backups to be kept off-site which provides an additional measure of security in the event of fire or flood damage, for instance. Cloud-based backups are also an option for maintaining off-site backups. If you have a lot of data, a RAID system makes sense as they can be used to create automatic backups by duplicating files across two or more discs. If one disc fails, the other will keep you up and running until the faulty disc is replaced. However, if both should fail (which can happen), you'll be glad you made an off-site backup. Indeed, it's good practice to have several levels of redundancy, combining a RAID with an on-site backup in a fire-proof safe, an off-site backup in a dedicated data storage facility and a cloud-based backup for when all else fails. How often you backup is entirely dependant upon how much you are prepared to lose should disaster strike. We've all had those occasions when we've been working on a lengthy document and suddenly the power goes out, losing an hours worth of work. While there are measures we can take to minimise the loss, it is nonetheless frustrating. But when a disk fails, an hours worth of work is the least of your worries; you might lose days, weeks, even months of work, depending on when you last made a backup. So it's vital that you make regular backups. It's also important to make system backups as well as data backups. System backups only need to be done after making a change to the system, such as when updating software or adding new programs but restoring a system from backup is many times quicker than re-installing from scratch. System backups don't need to be done as often as data backups but you should always have at least one full backup of the system and another of the data. Thereafter you can make incremental backups (recording the changes since the last backup) however full backups should be made periodically. To create an archive, you first choose which files should be part of that archive. If all your documents are in your personal folder then it's simply a matter of selecting that one folder and creating a complete backup. Keeping system files separate from your data, preferably on completely separate drives, makes it easy to create separate system and data archives, however backup programs allow you to create multiple backup configurations (or tasks) that you can easily recall. Note that every file on your system has an ARCHIVE attribute associated with it. Every time you backup a file, the ARCHIVE attribute is cleared. Every time you modify or create a file, the ARCHIVE attribute is set. This simple mechanism makes it possible to determine which files have changed since they were last backed up, thus allowing you to create incremental backups. So having selected the files you wish to backup, you simply choose a full backup or an incremental backup. Incremental backups obviously take less time to complete. A normal backup cycle requires that you make a full backup at the end of each week or at the end of each month, depending on how changeable your data is. In between these backups you will make incremental backups. However, it is important that you never overwrite the most recent backup, so always keep several volumes in rotation. For instance, if you perform weekly incremental backups with a full backup every month, it would be prudent to keep at least 3 full backups in circulation (covering the previous three months) and as many as 15 incremental backups, covering up to 5 weeks in each of those 3 months. So long as one of the three full backups works, the worst case would be losing 3 months work. This is why it is important to verify your backups as soon as you make them. It's no use making a backup if it cannot be relied upon. Backup programs normally include an option to automatically verify a backup after it is made. Above all else, if your data is vital, backup your backups with an off-site backup.
in 1508
A database is made up of related information in Tables and fields.
no, I don't
The process of creating and managing duplicate versions of a database. Replication not only copies a database but also synchronizes a set of replicasso that changes made to one replica are reflected in all the others. The beauty of replication is that it enables many users to work with their own local copy of a database but have the database updated as if they were working on a single, centralized database.For database applications where users are geographically widely distributed, replication is often the most efficient method of database access.
Incremental backups are the quickest method as they only back up changes made since the last backup, saving time and storage space. By backing up only the data that has changed, incremental backups are more efficient than full backups.
The process of creating and managing duplicate versions of a database. Replication not only copies a database but also synchronizes a set of replicas so that changes made to one replica are reflected in all the others. The beauty of replication is that it enables many users to work with their own local copy of a database but have the database updated as if they were working on a single, centralized database. For database applications where users are geographically widely distributed, replication is often the most efficient method of database access.