What foreground verification is

Foreground verification is a user-initiated process that checks if all expected object data exists on a Storage Node. Foreground verification is used to verify the integrity of a storage device.

Foreground verification is a faster alternative to background verification that checks the existence, but not the integrity, of object data on a Storage Node. If foreground verification finds that many items are missing, there might be an issue with all or part of a storage device associated with the Storage Node.

Foreground verification checks both replicated object data and erasure-coded object data, as follows:

Replicated objects: If a copy of replicated object data is found to be missing, StorageGRID automatically attempts to replace the copy from copies stored elsewhere in the system. The Storage Node runs an existing copy through an ILM evaluation, which will determine that the current ILM policy is no longer being met for this object because the missing copy no longer exists at the expected location. A new copy is generated and placed to satisfy the system's active ILM policy. This new copy might not be placed in the same location that the missing copy was stored.
Erasure-coded objects: If a fragment of an erasure-coded object is found to be missing, StorageGRID automatically attempts to rebuild the missing fragment in place on the same Storage Node using the remaining fragments. If the missing fragment cannot be rebuilt (because too many fragments have been lost), the Corrupt Copies Detected (ECOR) attribute is incremented by one. ILM then attempts to find another copy of the object, which it can use to generate a new erasure-coded copy.
If foreground verification identifies an issue with erasure coding on a storage volume, the foreground verification task pauses with an error message that identifies the affected volume. You must perform a recovery procedure for any affected storage volumes.

If no other copies of a missing replicated object or a corrupted erasure-coded object can be found in the grid, the Objects lost alert and the LOST (Lost Objects) legacy alarm are triggered.