Object storage migration

Backblaze B2 → Amazon S3

Move buckets, object keys, and binary content, checksums, etags, and integrity evidence, metadata, tags, and content headers, versions and delete markers, acls, bucket policy, and public access, encryption and customer-managed keys, lifecycle rules and storage classes, cors, events, and application integrations from Backblaze B2 to Amazon S3 with a reversible cutover, explicit exception ledger, and evidence-backed verification.

Typical timeline15–45 business days70–180 hours active work

Statusneeds review

Source profileBackblaze B2 documentation reviewed 2026-07-20

Destination profileAmazon S3 documentation reviewed 2026-07-20

Documentation date2026-07-20

Review window2026-07-202026-10-20

Evidence2 sources

This route needs review.Use it as a planning baseline, then verify the dated sources and test with representative data before production.

Before you migrate

Should you make this move?

Both platforms have a case. Compare what you gain with what you give up before scheduling the cutover.

Current platform

Backblaze B2

Reasons to stay

Straightforward object storage and predictable economics offer strong value for backups and large files
Managed sync, sharing, version history, and access controls reduce file-server work

Reasons to leave

Its regional footprint and surrounding cloud-service ecosystem are narrower than hyperscale alternatives
Shared links, permissions, comments, and ownership models do not map cleanly

New platform

Amazon S3

What gets better

Exceptional durability, scale, ecosystem reach, and storage-class breadth make it an industry default
Managed sync, sharing, version history, and access controls reduce file-server work

What gets worse

Policies, networking, replication, lifecycle rules, and request pricing are powerful but intricate
Shared links, permissions, comments, and ownership models do not map cleanly

Best of the move

Amazon S3: Exceptional durability, scale, ecosystem reach, and storage-class breadth make it an industry default. This removes a major source-side concern: Its regional footprint and surrounding cloud-service ecosystem are narrower than hyperscale alternatives.

Worst of the move

What you lose: Straightforward object storage and predictable economics offer strong value for backups and large files. What you inherit: Policies, networking, replication, lifecycle rules, and request pricing are powerful but intricate.

Jump to a section

01At a glance

Know the shape of the move.

Transfer outcome10 features audited

Clean0

Partial5

Manual4

Lost1

Mapping route9 of 9 fields have a destination path

SourceBackblaze B29 mapped fields

Automatic0

Transform5

Manual4

Unsupported0

DestinationAmazon S39 supported paths

This timeline assumes

Up to 500 TB, 500 million objects, 100 buckets, and 10 PB of monthly transfer
Administrators control both Backblaze B2 and Amazon S3, including billing, identity, APIs, integrations, and export permissions.
Backblaze B2 remains intact and recoverable until Amazon S3 completes one representative operating cycle.
A production-shaped pilot includes every object type, access class, edge case, and failure path.
The migration team preserves stable source identifiers and records durable evidence for every blocking check.

02What transfers

What survives the move.

“Partial” and “manual” are not footnotes. They are work that must be scheduled and verified.

Item	Outcome	Impact	What happens	Mitigation
Buckets, object keys, and binary content	partial	critical	Object bytes can move while namespace, region, naming limits, and multipart behavior differ. A successful bulk job therefore does not prove semantic parity between Backblaze B2 and Amazon S3.	Map buckets, object keys, and binary content explicitly, pilot every feature class, and reconcile accepted, changed, rejected, and excluded items.
Checksums, ETags, and integrity evidence	partial	critical	ETags are not universal content hashes and checksum support varies by upload and provider. A successful bulk job therefore does not prove semantic parity between Backblaze B2 and Amazon S3.	Map checksums, etags, and integrity evidence explicitly, pilot every feature class, and reconcile accepted, changed, rejected, and excluded items.
Metadata, tags, and content headers	partial	high	User metadata, tags, content type, disposition, encoding, and cache headers require explicit preservation. A successful bulk job therefore does not prove semantic parity between Backblaze B2 and Amazon S3.	Map metadata, tags, and content headers explicitly, pilot every feature class, and reconcile accepted, changed, rejected, and excluded items.
Versions and delete markers	partial	critical	Version IDs, delete markers, retention, and restore semantics are provider-specific. A successful bulk job therefore does not prove semantic parity between Backblaze B2 and Amazon S3.	Map versions and delete markers explicitly, pilot every feature class, and reconcile accepted, changed, rejected, and excluded items.
ACLs, bucket policy, and public access	manual	critical	Identity principals, ACLs, policy languages, public controls, and inherited access do not map safely. A successful bulk job therefore does not prove semantic parity between Backblaze B2 and Amazon S3.	Inventory and rebuild acls, bucket policy, and public access, then test normal, edge, failure, and rollback behavior.
Encryption and customer-managed keys	manual	critical	Key services, encryption headers, rotations, grants, and audit ownership change. A successful bulk job therefore does not prove semantic parity between Backblaze B2 and Amazon S3.	Inventory and rebuild encryption and customer-managed keys, then test normal, edge, failure, and rollback behavior.
Lifecycle rules and storage classes	manual	high	Transition timing, minimum duration, retrieval cost, and supported storage tiers differ. A successful bulk job therefore does not prove semantic parity between Backblaze B2 and Amazon S3.	Inventory and rebuild lifecycle rules and storage classes, then test normal, edge, failure, and rollback behavior.
CORS, events, and application integrations	manual	critical	CORS rules, notifications, queues, functions, and event schemas require replacement. A successful bulk job therefore does not prove semantic parity between Backblaze B2 and Amazon S3.	Inventory and rebuild cors, events, and application integrations, then test normal, edge, failure, and rollback behavior.
Signed URLs and S3 API compatibility	partial	critical	Endpoints, regions, signature behavior, unsupported API operations, and URL lifetimes can change clients. A successful bulk job therefore does not prove semantic parity between Backblaze B2 and Amazon S3.	Map signed urls and s3 api compatibility explicitly, pilot every feature class, and reconcile accepted, changed, rejected, and excluded items.
Replication, inventory, analytics, and billing history	lost	high	Provider-native reports, replication state, access logs, and cost history do not transfer as services. A successful bulk job therefore does not prove semantic parity between Backblaze B2 and Amazon S3.	Archive replication, inventory, analytics, and billing history as dated source evidence and define the new destination baseline.

03Field and feature mapping

Where each thing goes.

Source	Destination	Method	Notes
Backblaze B2: Buckets, object keys, and binary content	Amazon S3: approved buckets, object keys, and binary content representation	transform	Preserve source IDs, ownership, timestamps, access intent, and an explicit exception status for buckets, object keys, and binary content.
Backblaze B2: Checksums, ETags, and integrity evidence	Amazon S3: approved checksums, etags, and integrity evidence representation	transform	Preserve source IDs, ownership, timestamps, access intent, and an explicit exception status for checksums, etags, and integrity evidence.
Backblaze B2: Metadata, tags, and content headers	Amazon S3: approved metadata, tags, and content headers representation	transform	Preserve source IDs, ownership, timestamps, access intent, and an explicit exception status for metadata, tags, and content headers.
Backblaze B2: Versions and delete markers	Amazon S3: approved versions and delete markers representation	transform	Preserve source IDs, ownership, timestamps, access intent, and an explicit exception status for versions and delete markers.
Backblaze B2: ACLs, bucket policy, and public access	Amazon S3: approved acls, bucket policy, and public access representation	manual	Preserve source IDs, ownership, timestamps, access intent, and an explicit exception status for acls, bucket policy, and public access.
Backblaze B2: Encryption and customer-managed keys	Amazon S3: approved encryption and customer-managed keys representation	manual	Preserve source IDs, ownership, timestamps, access intent, and an explicit exception status for encryption and customer-managed keys.
Backblaze B2: Lifecycle rules and storage classes	Amazon S3: approved lifecycle rules and storage classes representation	manual	Preserve source IDs, ownership, timestamps, access intent, and an explicit exception status for lifecycle rules and storage classes.
Backblaze B2: CORS, events, and application integrations	Amazon S3: approved cors, events, and application integrations representation	manual	Preserve source IDs, ownership, timestamps, access intent, and an explicit exception status for cors, events, and application integrations.
Backblaze B2: Signed URLs and S3 API compatibility	Amazon S3: approved signed urls and s3 api compatibility representation	transform	Preserve source IDs, ownership, timestamps, access intent, and an explicit exception status for signed urls and s3 api compatibility.

04Before you begin

Make the move recoverable.

Backup procedure

Create the source-of-truth backup

Preserve Backblaze B2 data, configuration, access, and operating evidence before any destination write.

Export every available Backblaze B2 object and binary in scope, including buckets, object keys, and binary content, checksums, etags, and integrity evidence, metadata, tags, and content headers, versions and delete markers.
Capture configuration and runtime dependencies for acls, bucket policy, and public access, encryption and customer-managed keys, lifecycle rules and storage classes, cors, events, and application integrations.
Record counts, sizes, owners, timestamps, access classes, financial totals where applicable, and known exceptions.
Hash immutable exports, record tool versions and commands, and transform working copies only.

Proof to capture: A signed manifest accounts for every scoped record class, configuration object, binary, count, total, exception, and hash.

Transformation · Version-controlled migration workbook, SQL, or typed transformation code

Identity, schema, and disposition registry

Preserve stable identity and make every mapping or exclusion reviewable.

Inventory source types, identifiers, owners, states, and access.
Define one approved destination representation or explicit archive decision.
Reject unmapped critical items and produce an exception ledger.

Proof to capture: Save the input, output, command or tool settings, warnings, and final item counts.

Transformation · Official APIs, provider importers, checksums, and reconciliation scripts

Dependency-ordered migration package

Load prerequisite identities and configuration before dependent records and runtime actions.

Normalize encoding, timestamps, identifiers, nulls, and destination limits.
Run a representative pilot and retain request, response, and rejection evidence.
Reconcile the final delta before enabling destination production writers.

Proof to capture: Save the input, output, command or tool settings, warnings, and final item counts.

05Handle with care

The things most likely to hurt.

These are operating limits. Treat every “Stop if” condition as a blocked migration, not a suggestion.

Import

A completed migration hides missing or altered buckets, object keys, and binary content

criticalpossible likelihood

Headline counts look plausible while semantic, access, or relationship checks fail.

Consequence: The destination becomes authoritative with incomplete or misleading business data.
Mitigation: Reconcile by type, state, owner, access class, and representative record rather than total count alone.

Stop if: Any critical item lacks a verified destination, approved transformation, explicit exclusion, or recoverable archive.

Cutover

Backblaze B2 and Amazon S3 both perform production actions

criticalpossible likelihood

Users, schedules, webhooks, integrations, or traffic continue changing both systems.

Consequence: State diverges or customers receive duplicate, contradictory, or unsafe actions.
Mitigation: Freeze source writers and transfer one production owner at a time with an approved rollback.

Stop if: An unapproved source writer or destination duplicate action appears after the freeze.

Verification

Destination access or security is broader than approved

criticalpossible likelihood

A representative restricted user can read, change, export, or trigger an unauthorized item.

Consequence: Confidential, regulated, financial, or security-sensitive data is exposed or changed.
Mitigation: Apply least privilege before bulk loading and test every access class using ordinary identities.

Stop if: Any unauthorized read, write, export, administrative action, or secret access succeeds.

06Precise timeline

Do the work in this order.

Estimate forUp to 500 TB, 500 million objects, 100 buckets, and 10 PB of monthly transfer

Total elapsed15–45 business days

Active work70–180 hours

BufferAdd time for large Backblaze B2 exports, destination rate limits, unsupported features, identity exceptions, regulated data, or a strict downtime objective.

Days 1–4Inventory and decisions2–4 days

Days 3–8Backup and reconcile2–5 days

Days 6–20Map, transform, and pilot5–12 days

Days 18–35Bulk load, final delta, and switch2–8 days

Days 25–45Observe and close7–14 days

1
Days 1–4 · inventory
Inventory and decisions
8–16 hours active2–4 days elapsedOwner, legal, security, and finance review waiting
- Inventory Backblaze B2 data, configuration, identities, integrations, limits, and billing.
- Approve scope, owners, mappings, exclusions, acceptance thresholds, and rollback authority.
Depends on: Backblaze B2 and Amazon S3 administrator access
Stop / go checkpoint
Export?
Go when: Every critical item and production action has an owner and disposition.
Stop when: Authority, retention, billing, access, or system ownership is unclear.
2
Days 3–8 · backup
Backup and reconcile
8–20 hours active2–5 days elapsedProvider export processing waiting
- Create immutable data, configuration, binary, and audit exports.
- Reconcile source counts, totals, sizes, access classes, and hashes.
Depends on: Approved inventory and retention location
Stop / go checkpoint
Transform?
Go when: The signed source manifest and exports agree.
Stop when: Any critical dataset, binary, configuration, or recovery path is absent.
3
Days 6–20 · pilot
Map, transform, and pilot
25–70 hours active5–12 days elapsedDestination processing and owner review waiting
- Configure Amazon S3 and transform a production-shaped pilot.
- Test normal records, every feature class, edge cases, permissions, failures, and rollback.
Depends on: Verified source backup and approved mapping registry
Stop / go checkpoint
Scale?
Go when: Every pilot mapping and blocking verification check passes.
Stop when: Any critical invariant, access boundary, or production action lacks a safe destination.
4
Days 18–35 · cutover
Bulk load, final delta, and switch
20–55 hours active2–8 days elapsedImports, propagation, indexing, or synchronization waiting
- Freeze production writes and automated actions in Backblaze B2.
- Apply and reconcile the final delta, switch ownership to Amazon S3, and run all blocking checks.
Depends on: Passed pilot, stakeholder go decision, and rehearsed rollback
Stop / go checkpoint
Open production?
Go when: Amazon S3 is the sole production owner and every critical exception is resolved.
Stop when: A source writer remains active, a blocking check fails, or rollback is unavailable.
5
Days 25–45 · observe
Observe and close
9–19 hours active7–14 days elapsedRepresentative operating-cycle evidence waiting
- Monitor correctness, access, failures, latency, delivery, cost, and user outcomes.
- Sign the verification report and close rollback only after stable evidence.
Depends on: Verified cutover
Stop / go checkpoint
Close rollback?
Go when: No trigger occurs during the approved observation period.
Stop when: Data, access, delivery, routing, cost, or business results regress.

07The point of change

Cut over with a way back.

Go live

Cutover

Make Amazon S3 the only production system without losing the final Backblaze B2 delta.

Recommended window: A low-volume weekday morning with platform, data, security, networking, finance, and business owners available.

Freeze user, integration, schedule, and API writes in Backblaze B2.
Capture and reconcile the final source delta against the last verified checkpoint.
Apply the approved delta and configuration changes to Amazon S3.
Switch traffic, domains, integrations, credentials, automation, and user entry points in dependency order.
Run every blocking verification check and keep the source intact.

Proof to capture: Amazon S3 alone owns production, totals reconcile, exceptions are signed, and every blocking check has durable evidence.

Return to safety

Rollback

Return production ownership to Backblaze B2 without losing destination-era changes.

Deadline: Within seven days and before source data, plans, credentials, domains, keys, or retention settings are changed.

Stop new user, integration, schedule, and API writes in Amazon S3.
Restore prior Backblaze B2 traffic, domains, credentials, automation, and integration ownership.
Export and classify the Amazon S3 post-cutover delta.
Apply safe destination-era changes back to Backblaze B2 without duplicating actions.
Run the same blocking checks against the restored source.

Proof to capture: Backblaze B2 again owns production with current data and no duplicate destination action.

Rollback immediately when

Unexplained critical count, value, relationship, or checksum variance
Missing, corrupted, or exposed critical data
Duplicate production action or unresolved split-brain state
Failed access, security, delivery, routing, performance, or integration check
A critical feature has no safe destination replacement or rollback path

08Verification report

Prove the migration worked.

Every blocking check must pass. Capture the evidence before cleanup begins.

ID	Check	Method	Expected result	Evidence
`V-01`Blocking	Buckets, object keys, and binary content reconciliation	Compare source inventory, transformed output, destination results, and a stratified sample for buckets, object keys, and binary content.	Every in-scope item is present, intentionally transformed, explicitly excluded, or retained in the signed source archive.	Buckets, object keys, and binary content ledger with counts, exceptions, sample IDs, and owner sign-off.
`V-02`Blocking	Checksums, ETags, and integrity evidence reconciliation	Compare source inventory, transformed output, destination results, and a stratified sample for checksums, etags, and integrity evidence.	Every in-scope item is present, intentionally transformed, explicitly excluded, or retained in the signed source archive.	Checksums, ETags, and integrity evidence ledger with counts, exceptions, sample IDs, and owner sign-off.
`V-03`Blocking	Metadata, tags, and content headers reconciliation	Compare source inventory, transformed output, destination results, and a stratified sample for metadata, tags, and content headers.	Every in-scope item is present, intentionally transformed, explicitly excluded, or retained in the signed source archive.	Metadata, tags, and content headers ledger with counts, exceptions, sample IDs, and owner sign-off.
`V-04`Blocking	Versions and delete markers reconciliation	Compare source inventory, transformed output, destination results, and a stratified sample for versions and delete markers.	Every in-scope item is present, intentionally transformed, explicitly excluded, or retained in the signed source archive.	Versions and delete markers ledger with counts, exceptions, sample IDs, and owner sign-off.
`V-05`Blocking	ACLs, bucket policy, and public access reconciliation	Compare source inventory, transformed output, destination results, and a stratified sample for acls, bucket policy, and public access.	Every in-scope item is present, intentionally transformed, explicitly excluded, or retained in the signed source archive.	ACLs, bucket policy, and public access ledger with counts, exceptions, sample IDs, and owner sign-off.
`V-06`Blocking	Encryption and customer-managed keys reconciliation	Compare source inventory, transformed output, destination results, and a stratified sample for encryption and customer-managed keys.	Every in-scope item is present, intentionally transformed, explicitly excluded, or retained in the signed source archive.	Encryption and customer-managed keys ledger with counts, exceptions, sample IDs, and owner sign-off.
`V-07`	Lifecycle rules and storage classes reconciliation	Compare source inventory, transformed output, destination results, and a stratified sample for lifecycle rules and storage classes.	Every in-scope item is present, intentionally transformed, explicitly excluded, or retained in the signed source archive.	Lifecycle rules and storage classes ledger with counts, exceptions, sample IDs, and owner sign-off.
`V-08`Blocking	CORS, events, and application integrations reconciliation	Compare source inventory, transformed output, destination results, and a stratified sample for cors, events, and application integrations.	Every in-scope item is present, intentionally transformed, explicitly excluded, or retained in the signed source archive.	CORS, events, and application integrations ledger with counts, exceptions, sample IDs, and owner sign-off.

09Post-migration cleanup

Remove the scaffolding safely.

Safe after: One complete operating cycle, at least seven stable days, and owner sign-off on every blocking check and exception.

Create final Backblaze B2 exports and archive verification, access, financial, and rollback evidence.
Revoke temporary credentials, API keys, webhooks, elevated roles, and migration network access.
Remove obsolete jobs, embeds, domains, integrations, collectors, routes, and DNS records.
Keep the source intact and read-only through the approved legal and operational retention window.
Cancel paid plans only after billing, legal, security, evidence, and recovery review.
Schedule the next Amazon S3 backup, restore test, access review, and migration-playbook review.

Sources and evidence

Verify against the primary material.

Platform behavior changes. Check these sources and the review dates above before executing a production migration.

Backblaze B2: official portability and migration documentationAccessed 2026-07-20
Amazon S3: official portability and migration documentationAccessed 2026-07-20

Know the shape of the move.

This timeline assumes

What survives the move.

Where each thing goes.

Make the move recoverable.

Create the source-of-truth backup

Identity, schema, and disposition registry

Dependency-ordered migration package

The things most likely to hurt.

A completed migration hides missing or altered buckets, object keys, and binary content

Backblaze B2 and Amazon S3 both perform production actions

Destination access or security is broader than approved

Do the work in this order.

Inventory and decisions

Export?

Backup and reconcile

Transform?

Map, transform, and pilot

Scale?

Bulk load, final delta, and switch

Open production?

Observe and close

Close rollback?

Cut over with a way back.

Cutover

Rollback

Prove the migration worked.

Remove the scaffolding safely.

Verify against the primary material.