Object is incorrectly updated at object storage during the AFM reconcile operation and may cause undetected data loss. IBM Storage Scale versions 5.1.9.3 - 5.1.9.5 are potentially affected.

Description

When the Manual Update (MU) mode is in use at the AFM cache site, and an existing file in the cache is renamed and recreated with the same name, the AFM reconcile operation uploads the file to the AFM home site but may incorrectly update the file at the AFM home site. With the file incorrectly updated at the AFM home site, an evict operation on the file at the AFM cache site would result in undetected data loss.

For further information about the AFM reconcile operation, visit AFM to cloud object storage policy based upload for manual updates mode in IBM Storage Scale documentation.

Users affected:
Users running AFM on IBM Storage Scale versions 5.1.9.3 - 5.1.9.5 or Storage Scale System 6.1.9.3 are potentially affected.

Problem determination:
Create one AFM Read Only (RO) mode fileset with the same object target and read the files from object storage. Read all files from this object storage to local cache and run data consistency tool (like md5sum) and list out the output for each file. Run the same data consistency tool for AFM Manual Update (MU) mode fileset files and list out the output for each file. Compare the output and find the mismatched files.

Verification steps:
Users can check through data compare for the file between AFM cache and corresponding file at object storage sites.