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CSA Loom — the Microsoft Fabric experience for Azure tenants where Fabric isn't yet available: lakehouses, warehouses, notebooks, semantic models, Activator rules, Data Agents, across Commercial, GCC, GCC-High, and DoD IL5

Multi-cloud data virtualization

Comparative positioning note

This document is written from the perspective of Microsoft Azure, Cloud Scale Analytics, and CSA Loom. Any description of third-party or competing products, services, pricing, or capabilities is derived from publicly available documentation and sources believed accurate at the time of writing, and is provided for general comparison only. We do not claim expertise in, or authority over, any non-Microsoft product or service; the respective vendor's official documentation is the authoritative source for their offerings, which may change over time. Nothing here is intended to disparage any vendor — where a competing product has genuine advantages, we aim to note them honestly. Verify all third-party details against the vendor's current official documentation before making decisions.

CSA Loom is Azure-first but supports read-side virtualization across cloud boundaries via ADLS Gen2 shortcuts + Loom's Shortcuts service (covered in OneLake parity).

Supported cross-cloud reads

Source Mechanism
AWS S3 ADLS Gen2 shortcut via Loom Shortcuts service; IAM role for delegated credential
Google Cloud Storage ADLS Gen2 shortcut; GCS workload identity federation
ADLS Gen2 (another tenant) Cross-tenant shortcut with delegated SAS / Entra B2B
Snowflake (read-only) External data sharing via Delta Sharing protocol (v1.1)
Databricks (other workspace) Delta Sharing protocol

All cross-cloud reads: - Are customer-controlled — Loom doesn't initiate cross-cloud data movement - Carry an audit trail — every shortcut access logged - Honor per-boundary egress rules — IL5 restricts which external destinations are reachable via Azure Firewall app rules

When to use cross-cloud virtualization

Scenario Pattern
Read public datasets from S3 (NOAA, Census, etc.) ADLS Gen2 shortcut with anonymous public access
Enrich Loom analytics with partner data in another cloud Cross-tenant shortcut + B2B identity
Cross-cloud analytics across hybrid Fabric Commercial + Loom Gov OneLake shortcut from Fabric to Loom ADLS Gen2 path (when Fabric reaches Gov)
Migrate from S3 / GCS to ADLS Gen2 Use shortcut as bridge; gradually copy to native ADLS

When NOT to use cross-cloud

  • Customer hasn't approved the cross-cloud egress
  • The data is restricted by IL5 / ITAR / CUI policies that prevent external read
  • Latency-sensitive use cases (cross-cloud reads have 100-500 ms per-request latency)

What Loom doesn't support

  • Cross-cloud writes — Loom doesn't write to S3 / GCS
  • Federated query joining S3 + GCS + ADLS in one query — joins require landing data in ADLS first (via shortcut + materialize)
  • Cross-cloud Power BI Direct Lake — Direct Lake reads from ADLS / OneLake only

Cross-cloud B2B identity

For human cross-cloud collaboration: - Entra ID Cross-Cloud Settings configures B2B trust between Azure Commercial + Azure Gov tenants - Users invited as guests can read approved resources - Conditional Access policies on both sides enforce MFA + compliance - Documented in Hybrid topology use case