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Reference Hardware
mc admin rebalance
Permission
This command requires that the user performing it have the admin:Rebalance policy action for the deployment.
Description
The mc admin rebalance command allows starts, monitors, or stops a rebalancing operation on a MinIO deployment.
Rebalancing redistributes objects across all pools in the deployment.
MinIO does not automatically rebalance objects when adding a new server pool. Instead, MinIO writes new objects to the pool with relatively more free space compared to the other available pools on the deployment. Triggering a manual rebalancing procedure prompts MinIO to scan the entire deployment and move objects as necessary to achieve a similar available free space across all pools.
This is an expensive and time consuming operation. Consider only running a rebalance procedure during light or no use of the deployment. If write operations do occur during a rebalance operation, they process in parallel and write to a pool not actively in rebalancing.
You can stop a rebalance and start it again later as needed.
Follow the progress of an ongoing rebalance operation using the following command:
mc admin trace --call rebalance ALIAS
Use mc admin on MinIO Deployments Only
MinIO does not support using mc admin commands with other
S3-compatible services, regardless of their claimed compatibility with MinIO
deployments.
The mc admin rebalance command has the following subcommands:
Subcommand |
Description |
|---|---|
Starts a rebalance operation on a MinIO deployment. |
|
Outputs the current status of an in-progress rebalance operation. |
|
Stops an in-progress rebalance operation. |
Syntax
- mc admin rebalance start
Start a rebalance operation for a MinIO deployment.
Consider a MinIO deployment with two pools with an assigned alias of
minio1. One pool has 250 GB of free space while the other pool has 3 TB of free space.The
mc admin rebalancecommand shifts objects from the pool with less free space to the pool with more free space so that there is roughly equal free space on both pools.mc admin rebalance start minio1
The command has the following syntax:
mc [GLOBALFLAGS] admin rebalance start ALIAS
Replace ALIAS with the alias of a MinIO deployment to rebalance.
- mc admin rebalance status
Queries the deployment with an active rebalance process and returns information about the status of the rebalance process.
The status returns the ID of the rebalance operation, the time of the operation, and details for each pool on the deployment. For each pool, the status shows the pool ID, the pool’s rebalance status, the percentage of used space, and rebalance progress for the pool.
mc admin rebalance status minio1
The command has the following syntax:
mc [GLOBALFLAGS] admin rebalance ALIAS
Replace ALIAS with the alias of the MinIO deployment.
- mc admin rebalance stop
Ends an in-progress rebalance job on the specified deployment.
mc admin rebalance stop minio1
The command has the following syntax:
mc [GLOBALFLAGS] admin rebalance stop ALIAS
Replace ALIAS with the alias of the MinIO deployment.
Global Flags
This command supports any of the global flags.
Behavior
Back Up Cluster Settings First
Use the mc admin cluster bucket export and mc admin cluster iam export commands to take a snapshot of the bucket metadata and IAM configurations respectively prior to starting decommissioning.
You can use these snapshots to restore bucket/IAM settings to recover from user or process errors as necessary.
Rebalancing Ignores Expired Objects and Trailing DeleteMarker
Starting with https://github.com/minio/minio/releases/tag/RELEASE.2023-06-23T20-26-00Z, rebalancing ignores object versions which have expired based on the configured lifecycle rules for the parent bucket.
Rebalancing also ignores objects where the only remaining version is a delete marker. This avoids inter-pool I/O for objects already considered fully deleted.
MinIO relies on the scanner to capture and remove those expired objects or trailing DeleteMarker objects.
