Fail-over techniques in database mirroring.There are different techniques for database mirroring.
The following table summarizes which forms of failover are supported under each of the operating modes.
High performance
|
High-safety mode without a witness
|
High-safety mode with a witness
| |
Automatic failover
|
No
|
No
|
Yes
|
Manual failover
|
No
|
Yes
|
Yes
|
Forced service
|
Yes
|
Yes
|
No
|
Automatic Fail-Over:
To test database mirroring auto fail over solution you need to restart database engine and your Principal and Mirror servers will be reversed but you need to set your mirroring solution as (Principal – Witness - Mirror). You can view how we can test auto fail over solution look at this link.
Manual Fail-Over:
During a manual failover, the principal and mirror server roles are swapped for the database on which the failover occurs. The mirror database becomes the principal database and the principal database becomes the mirror. For example, the following table shows the how a manual failover swaps the roles of two mirroring partners: System
Forced Fail-Over:
We are now looking into Forced Service for database mirroring. This option is available against high safety but automatic failover is not available. In the event of failure of the principal, the database service becomes unavailable. You need manual intervention to make the database service available.
No comments:
Post a Comment