What Is a Consistency Check?
Updated: April 21, 2010
Applies To: System Center Data Protection Manager 2010
Data Protection Manager (DPM) provides two methods for synchronizing a replica: incremental synchronization and synchronization with consistency check. Synchronization with consistency check, also referred to simply as a consistency check, is the process by which DPM checks for and corrects inconsistencies between a protected data source and its replica. As part of the synchronization process, a consistency check performs block-by-block verification to ensure that all the data on the replica is consistent with the protected data. This process is slower than incremental synchronization because all the data on the replica is compared rather than just applying the data changes to the replica.
DPM automatically initiates a consistency check as a daily task if you select the option to automatically perform consistency check if the replica is inconsistent or if you have scheduled a daily consistency check for a protection group.
You may need to perform synchronization with consistency check to repair inconsistencies between the data on the protected computer and the replica on the DPM server. You can configure your protection group to allow DPM to initiate a consistency check as a daily task if you select the option to automatically perform consistency check if the replica is inconsistent. We recommend you to use this option for workloads lesser than 1-terabyte or workloads within a data center
You can also schedule a daily consistency check during off-peak hours to ensure that the replica remains consistent with the protected data. A scheduled consistency check will only run if inconsistencies are detected during synchronization. We recommend you to use this option for large workloads or for data that is backed up over WAN.
If a replica becomes inconsistent because of a change journal overflow or an unexpected shutdown of the protected computer, a consistency check must be performed. You can perform a one-time manual consistency check or, if a daily consistency check is scheduled, you can wait until DPM performs the consistency check. When a consistency check is performed and inconsistencies between the protected volume and the replica volume are found, DPM makes the replica consistent.
|The performance of the protected computer and the DPM server will be affected while a consistency check is running. It is best to schedule consistency checks and perform one-time consistency checks during off-peak hours.|