Table of Contents
MinIO supports server-side and client-side replication of objects between source and destination buckets.
- Server-Side Bucket Replication
Configure per-bucket rules for automatically synchronizing objects between buckets within the same MinIO cluster or between two independent MinIO Clusters. MinIO applies rules as part of object write operations (e.g.
PUT) and automatically synchronizes new objects and object mutations, such as new object versions or changes to object metadata.
MinIO server-side bucket replication only supports MinIO clusters for the remote replication target.
- Client-side Bucket Replication
mc mirrorprocess to synchronize objects between buckets within the same S3-compatible cluster or between two independent S3-compatible clusters. Client-side replication using
mc mirrorsupports MinIO-to-S3 and similar replication configurations.
MinIO server-side bucket replication is an automatic bucket-level configuration that synchronizes objects between a source and destination bucket. MinIO server-side replication requires the source and destination bucket be MinIO clusters. The source and destination bucket may be the same MinIO cluster or two independent MinIO clusters.
For each write operation to the bucket, MinIO checks all configured replication rules for the bucket and applies the matching rule with highest configured priority. MinIO synchronizes new objects and object mutations, such as new object versions or changes to object metadata. This includes metadata operations such as enabling or modifying object locking or retention settings.
MinIO server-side bucket replication is functionally similar to Amazon S3 replication while adding the following MinIO-only features:
Source and destination bucket names can match, supporting site-to-site use cases such as Splunk or Veeam BC/DR.
Simplified implementation than S3 bucket replication configuration, removing the need to configure settings like AccessControlTranslation, Metrics, and SourceSelectionCriteria.
Active-Active (Two-Way) replication of objects between source and destination buckets.
Multi-Site replication of objects between three or more MinIO deployments (New in RELEASE.2021-09-23T04-46-24Z).
MinIO uses a replication queuing system with multiple concurrent replication workers operating on that queue. MinIO continuously works to replicate and remove objects from the queue while scanning for new unreplicated objects to add to the queue.
MinIO sets the
X-Amz-Replication-Status metadata field according to the
replication state of the object:
The object has not yet been replicated. MinIO applies this state
if the object meets one of the configured replication rules on the
bucket. MinIO continuously scans for
For multi-site replication, objects remain
The object has successfully replicated to the remote cluster.
The object failed to replicate to the remote cluster.
MinIO continuously scans for
The object is itself a replica from a remote source.
The replication process generally has one of the following flows:
PENDING -> COMPLETED
PENDING -> FAILED -> COMPLETED
MinIO supports specifying either asynchronous (default) or synchronous replication for a given remote target.
With the default asynchronous replication, MinIO completes the originating
PUT operation before placing the object into a replication queue. The originating client may therefore see a
PUT operation before the object is replicated. While
this may result in stale or missing objects on the remote, it mitigates
the risk of slow write operations due to replication load.
With synchronous replication, MinIO attempts to replicate the object prior to
completing the originating
PUT operation. MinIO returns a successful
operation whether or not the replication attempts succeeds. While this may
result in more reliable synchronization between the source and remote target,
it may also increase the time of each write operation due to replication load.
mc replicate resync command can reset replication synchronization
for a remote target. The resynchronization process attempts to queue all
objects on the source bucket regardless of their
replication status. Resynchronization
primarily supports recovery after partial or total loss of a remote
Initiating resynchronization on a bucket uses the same core replication scanner and queue system for detecting and synchronizing objects. MinIO does not prioritize objects in the target bucket, nor does it empty or otherwise modify the queue to favor objects in the target bucket. MinIO skips synchronizing those objects whose remote copy exactly match the source, including object metadata.
mc replicate resync operates at the bucket level and does
not support prefix-level granularity. Initiating resynchronization on a large
bucket may result in a significant increase in replication-related load
and traffic. Use this command with caution and only when necessary.
MinIO supports replicating delete operations, where MinIO synchronizes deleting specific object versions and new delete markers. Delete operation replication uses the same replication process as all other replication operations.
MinIO only replicates explicit client-driven delete operations. MinIO does not replicate objects deleted due to lifecycle management expiration rules.
For delete marker replication, MinIO begins the replication process after
a delete operation creates the delete marker. MinIO uses the
X-Minio-Replication-DeleteMarker-Status metadata field for tracking
delete marker replication status. In
replication configurations, MinIO may produce duplicate delete markers if
both clusters concurrently create a delete marker for an object or
if one or both clusters were down before the replication event synchronized.
For replicating the deletion of a specific object version, MinIO marks the
object version as
PENDING until replication completes. Once the remote
target deletes that object version, MinIO deletes the object on the source.
While this process ensures near-synchronized version deletion, it may result
in listing operations returning the object version after the initial
delete operation. MinIO uses the
tracking delete version replication status.
MinIO requires explicitly enabling versioned deletes and delete marker
replication . Use the
mc replicate add --replicate field to
specify both or either
delete-marker to enable versioned
deletes and delete marker replication respectively. To enable both, specify both
strings using a comma separator
MinIO Trims Empty Object Prefixes on Source and Remote Bucket
If a delete operation removes the last object in a bucket prefix, MinIO
recursively removes each empty part of the prefix up to the bucket root.
MinIO only applies the recursive removal to prefixes created implicitly as
part of object write operations - that is, the prefix was not created using
an explicit directory creation command such as
If a replication rule enables replication delete operations, the replication process also applies the implicit prefix trimming behavior on the destination MinIO cluster.
For example, consider a bucket
photos with the following object prefixes:
photos/NYE21 is the only prefix explicitly created using
All other prefixes were implicitly created as part of writing the object
located at that prefix.
A command removes
myphoto.jpg. MinIO automatically trims the empty
A command then removes the
myotherphoto.jpg. MinIO automatically trims the
/februaryprefix and the now-empty
A command removes the
NewYears.jpgobject. MinIO leaves the
/NYE21prefix remains in place since it was explicitly created.
MinIO by default does not enable existing object replication. Objects
created before replication was configured or while replication is
disabled are not synchronized to the target deployment.
mc RELEASE.2021-06-13T17-48-22Z and
RELEASE.2021-06-07T21-40-51Z, MinIO supports enabling
replication of existing objects in a bucket.
Enabling existing object replication marks all objects or object prefixes that satisfy the replication rules as eligible for synchronization to the source cluster, even if those objects were created prior to configuring or enabling replication. You can enable existing object replication while configuring or modifying a replication rule:
For new replication rules, include
"existing-objects"to the list of replication features specified to
mc replicate add --replicate.
For existing replication rules, add
"existing-objects"to the list of existing replication features using
mc replicate edit --replicate. You must specify all desired replication features when editing the replication rule.
Enabling existing object replication does not increase the priority of objects pending replication. MinIO uses the same core replication scanner and queue system for detecting and synchronizing objects regardless of the enabled replication feature. The time required to fully synchronize a bucket depends on a number of factors, including but not limited to the current cluster replication load, overall cluster load, and the size of the namespace (all objects in the bucket).
MinIO does not synchronize existing unversioned objects. Specifically, the
bucket must have versioning enabled when the
object was created. You can use the
mc cp command to create a
“versioned” copy of that object. Once that object replicates successfully,
you can delete the unversioned object (versionid =
MinIO existing object replication implements functionality similar to AWS: Replicating existing objects between S3 buckets without the overhead of contacting technical support.