A consistency check is a strategy used to harmonize data found on a computer system. The idea behind the check is to ensure that all data is synchronized between primary and secondary data groups, also known as protection groups and replicas. A consistency check may be configured to take place at designated times or implemented manually if there is suspicion of some type of conflict in data since the most recently completed check.
Resolving internal conflicts is the main focus of a consistency check. Many systems include what is known as a data protection manager that reviews data in blocks, making sure the protection group and the replica are in harmony. In the event updates in data have occurred with the protection group but not the replica, the manager adds the updates to the secondary data group, resolving the conflict.
The process of managing this type of check varies somewhat from one system to another. Usually a system administrator can establish a recurring schedule for running the check at least once every twenty-four hours. For example, the check may be set to occur just before midnight each day. It is also possible to set the recurring checks on specific days of the calendar month, or to occur on a weekly or biweekly basis. Establishing a schedule of standing or recurring checks does not limit the ability of the administrator to conduct random checks when and as desired.
The actual process of conducting a consistency check can take some time. This is because the check is not simply looking for exceptions but is actively comparing each and every block of data between the two groups. Doing so makes it possible to identify any corruption that may have occurred in one group or the other, and provides the chance to repair the damage. Some systems will flag the discrepancies, allowing a system administrator to review the conflicting data before the chances actually occur.
Attempting to restart a system while a check is underway is usually not recommended. This process may damage data or cause some other ill effect, based on how the system is configured. If an emergency consistency check is initiated, it is usually a good idea of end users to refrain from attempting to utilize the system for a any reason until the check is complete.
In addition to taking time to complete, this check can also slow down other activities on the system. This means end users may notice a change in how quickly they are able to access different databases or use any of the other programs connected with the system. For this reason, a computer consistency check is often set to occur in off-peak times, such as after the workday is completed or at night when the users of a household computer are asleep.