Moving Delta data between Databricks tenants: storage copy, Delta Sharing or deep clone

#1. Options

#2. Option A: keep the storage

• External tables in the source can be registered as external tables in the target UC once the target's access connector/IAM role can read the storage (cross-tenant managed identity access isn't possible directly; you'd typically move the storage account's subscription to the target tenant, then grant the new access connector).
• Managed tables in the source live in the source metastore's managed storage — use B or C for those.

#3. Option B: copy files, then register

Copy the whole table folder (data files and _delta_log):

azcopy copy "https://stsrclake.dfs.core.windows.net/silver/sales/orders/?<src-sas>" \
            "https://sttgtlake.dfs.core.windows.net/silver/sales/orders/?<tgt-sas>" --recursive

For managed tables, find the storage path with DESCRIBE DETAIL and copy that folder. Then register in the target:

CREATE TABLE prod_sales.orders.orders USING DELTA
LOCATION 'abfss://silver@sttgtlake.dfs.core.windows.net/sales/orders';

This creates an external table with full history. If you want UC managed tables, CREATE TABLE ... DEEP CLONE from the external table into a managed catalog, then drop the external copy (or use the external-to-managed conversion command where available in your runtime).

Copy while writes are paused, or copy and then re-copy changed files (azcopy sync) at cutover. Never copy a table while it's being vacuumed.

#4. Option C: Delta Sharing between accounts

1. In the source: create a recipient for the target metastore's sharing identifier; create a share with the tables (enable history sharing / CDF if you want incremental reads).

CREATE SHARE migr_sales;
ALTER SHARE migr_sales ADD TABLE prod.sales.orders WITH HISTORY;
CREATE RECIPIENT newco_metastore USING ID 'azure:centralindia:<target-metastore-uuid>';
GRANT SELECT ON SHARE migr_sales TO RECIPIENT newco_metastore;

2. In the target: create a catalog from the share, then materialise:

CREATE CATALOG src_share USING SHARE oldco_provider.migr_sales;
CREATE TABLE prod_sales.orders.orders AS SELECT * FROM src_share.sales.orders;

3. Incremental sync until cutover: MERGE using change data feed (table_changes) from the shared table, or reload partitions.

#5. Validate

SELECT COUNT(*), SUM(hash(*)) FROM prod.sales.orders;   -- run in source and target and compare

Plus schema comparison (DESCRIBE TABLE), partition counts, and spot checks on recent data. Check table properties (CDF, retention, clustering) were reapplied.

#6. Plan the volume

Measure throughput with one large table first. Copy cold, large tables early; leave small, hot tables for the cutover window.

Warning

Copying _delta_log and data files separately or out of order can produce a broken table (log entries pointing to missing files). Copy the full folder in one operation, and verify with DESCRIBE HISTORY and a full read in the target.