Does macOS support SMB transparent failover in HA NAS clusters?
Applicable Products
QuTS hero h5.3.0 or later
Answer
No. When a failover occurs in a high-availability (HA) cluster of QNAP NAS devices, any ongoing SMB file transfers between the cluster and a macOS client will be interrupted and will not resume after the failover. You must reinitiate the file transfer manually.
Details
QNAP HA clusters support SMB transparent failover with Persistent Handles. However, the feature currently only works with Windows clients.
Persistent Handle—also known as Durable Handle v2 (DH2C)—is a feature introduced by Microsoft that allows file operations to automatically resume after a temporary SMB connection drop. This improves connection reliability and data consistency.
However, the SMB implementation in macOS, which is based on Apple's own SMB stack, does not currently support DH2C.
Further Reading
Does Linux support SMB transparent failover in HA NAS clusters?
