IBM Cloud Object Storage cross-region timestamp drift affecting object version ordering

Context

IBM Cloud Object Storage (COS) supports multi-region and cross-region bucket configurations where object versions are time-stamped by the system clock of the receiving endpoint. In deployments spanning multiple regions, each data center operates on its own clock, introducing potential drift of tens to hundreds of milliseconds.

Uncertainty

The eventual consistency model for metadata updates means a PUT request routed to one regional endpoint may receive a timestamp that differs from a subsequent PUT routed to another region. Applications that rely on strict version ordering—such as audit logs, immutable event streams, or conflict-resolution logic—may observe versions appearing out of sequence when listed via a global endpoint or when replicating across regions.

Goal

Determine whether the observed timestamp drift is bounded and documented, and whether COS provides any mechanism (such as logical clocks, version IDs, or conditional writes) to establish a total order of object versions across regions without sacrificing the latency benefits of regional endpoints.

Specific questions:

1. What is the maximum expected clock drift between IBM COS regional endpoints, and is it published in any SLA or technical specification?
2. Can applications safely use the VersionId returned on PUT as a globally monotonic identifier, or does it only reflect local endpoint ordering?
3. Are there recommended patterns—such as client-side logical timestamps or conditional If-Match headers—to achieve cross-region version ordering without routing all writes through a single regional endpoint?