: The error "Failed to flush file buffers" often precedes the block notification error, suggesting the NAS cannot confirm the data was written.
The Veeam error "" typically indicates a critical communication or I/O failure between the Veeam Data Mover and the backup storage, often caused by storage write issues , network timeouts , or corrupted snapshots . This specific error is frequently seen when backing up to CIFS/SMB shares or when the source disk contains bad sectors that prevent consistent block reading. Immediate Troubleshooting Steps
: On the source machine (VM or physical), run chkdsk /f to identify and repair file system errors or bad blocks that could be causing the "failed to download disk" error. : The error "Failed to flush file buffers"
: Check the Windows Event Viewer for Event ID 25 or 36 . These indicate the Shadow Copy was deleted because it could not grow, often due to high I/O load. 3. Transport Mode and Proxy Configuration
: If the backup always fails at the same block, it likely indicates a physical bad sector on the source drive. Immediate Troubleshooting Steps : On the source machine
: Sometimes the incremental backup chain becomes inconsistent. Running an Active Full backup can reset the chain and bypass metadata corruption. Common Causes and Solutions 1. Storage Protocol Issues (SMB/CIFS)
Using SMB shares as a repository is a common trigger for this error because of how it handles file buffers. often due to high I/O load.
: Use vendor-specific tools or CrystalDiskInfo to check for S.M.A.R.T. errors on the disks.