Understanding Consistency Checks in Alike
This article explains how consistency checks work in Alike, and the difference between Optimize consistency checks and forced consistency checks.Consistency checks perform verifications on Alike's Data Store, checking for corruption. Running an Optimize job without a consistency check will perform some checks. Running a full or quick check is more comprehensive, and is recommended on a weekly or monthly basis.
Consistency & Quick Checks
You can perform a consistency check after any Optimize job by selecting either “Perform a full consistency check of the Alike data store” or “Perform a quick consistency check of the Alike data store”. Full checks verify all data stored, while quick checks verify meta-information. Quick checks are about 30% faster.
Periodic System Consistency Checks
Starting in Alike 1.3.5, Alike automatically triggers a job that checks system consistency. This job will run while your scheduled backup and restore jobs proceed as usual. This job will run every 35 days unless another Optimize job with a full Consistency Check occurs before that time. It will also run for the first time shortly after you upgrade from an install of Alike older than 1.3.5. If there are errors during this job, Alike attempts to isolate the errors and will report its progress to you in the Activity page under the job "Alike System Consistency Check".
Forced Consistency Checks
If an Optimize job encounters bad data during its run, it will automatically switch to a Consistency Check. This will cause running jobs to fail. New jobs that attempt to run during this forced check will also fail.
In versions of Alike prior to 1.3.6, Quick Consistency Checks are forced at startup if Alike detected a discrepancy between its installation files and the BDB files (located where you have configured your Data Store). The most common reason for this discrepancy is if you have restored your BDB files from a backup, or restored your Alike installation from a backup. It's also possible that a consistency check is needed if Alike is stopped abruptly when the OS crashes or loses power.
If a check is forced at startup, Alike will only examine BDBs it believes are out of sync, making the process faster than a check run from an Optimize job. However, during this time, jobs will fail with the message "BDB refused putBlock since it is not initialized”. After the check completes, jobs will run normally.
Repairing an Out-of-Sync Installation
Starting in Alike 1.3.6, if Alike notices a discrepancy between its installation files and the data store, the services will not start, and the following error will be logged:
If you encountered this while attempting to recover your Alike installation or its data, please contact QuorumSoft Support for assistance.
Otherwise, you may run 'DSRepairTool.exe' to correct this situation. Please run an Optimize job with a full consistency check asap.
While unusual, you may see this error if the machine crashed while Alike was running a backup job. If this is the case, you may safely run DSRepair.exe and restart Alike. After you restart Alike, you should run an Optimize job with a full consistency check.
If you see this message after you have recovered your Alike installation directory from a tape or disk archive, or recovered your Data Store from a tape or disk archive, proceed with caution. You will probably need to run a repair installation to correct this issue. Contact support if you have questions on how to proceed.
See Also:
Data Reclamation in Alike
Disaster Recovery in Alike Standard
Services Will not Start
