# Decommissioning

Decommissiong is a mechanism in MinIO to drain older pools (usually with old hardware) and migrate the content from such pools to a newer pools (usually better hardware). Decommissioning spreads the data across all pools - for example, if you decommission `pool1`, all the data from `pool1` spreads across `pool2` and `pool3`.

## Features

	}

	// Make pool unwritable before decommissioning.
	if err := z.StartDecommission(ctx, indices...); err != nil {
		return err
	}

	go func() {
		for _, idx := range indices {
			// decommission all pools serially one after
			// the other.
			z.doDecommissionInRoutine(ctx, idx)
		}
	}()

	// Successfully started decommissioning.
	return nil
}

- Reload() of MinIO server arguments without fully restarting the process.

- Expanding 1 node at a time by automating the process of creating a new pool
  and decommissioning to provide a functionality that smaller deployments
  care about.

if [ "${expected_checksum}" != "${got_checksum}" ]; then
	echo "BUG: decommission failed on encrypted objects: expected ${expected_checksum} got ${got_checksum}"
	exit 1
fi

# after decommissioning, compare listings in bucket2 and tiered
./mc version info myminio/bucket2 | grep -q "versioning is enabled"
ret=$?
if [ $ret -ne 0 ]; then
	echo "BUG: expected versioning enabled after decommission on bucket2"

	entry.Tags = make(map[string]interface{}, len(opts.Tags))
	for k, v := range opts.Tags {
		entry.Tags[k] = v
	}

	// Merge tag information if found - this is currently needed for tags
	// set during decommissioning.
	if reqInfo := logger.GetReqInfo(ctx); reqInfo != nil {
		reqInfo.PopulateTagsMap(opts.Tags)
	}
	ctx = logger.SetAuditEntry(ctx, &entry)
	logger.AuditLog(ctx, nil, nil, nil)
}

// from healObject)
func (fi FileInfo) Healing() bool {
	_, ok := fi.Metadata[xMinIOHealing]
	return ok
}

// SetDataMov marks object (version) as being currently
// in movement, such as decommissioning or rebalance.
func (fi *FileInfo) SetDataMov() {
	if fi.Metadata == nil {
		fi.Metadata = make(map[string]string)
	}
	fi.Metadata[xMinIODataMov] = "true"
}

	er := s.getHashedSet(object)
	return er.PutObjectMetadata(ctx, bucket, object, opts)
}

// DecomTieredObject - moves tiered object to another pool during decommissioning.
func (s *erasureSets) DecomTieredObject(ctx context.Context, bucket, object string, fi FileInfo, opts ObjectOptions) error {
	er := s.getHashedSet(object)
	return er.DecomTieredObject(ctx, bucket, object, fi, opts)
}

	}
	return nil
}

// DecomTieredObject - moves tiered object to another pool during decommissioning.
func (z *erasureServerPools) DecomTieredObject(ctx context.Context, bucket, object string, fi FileInfo, opts ObjectOptions) error {
	object = encodeDirObject(object)
	if z.SinglePool() {
		return fmt.Errorf("error decommissioning %s/%s", bucket, object)
	}
	if !opts.NoLock {
		ns := z.NewNSLock(bucket, object)

		MTime: oi.ModTime,
	})
	return setRestoreHeaderFn(oi, err)
}

// DecomTieredObject - moves tiered object to another pool during decommissioning.
func (er erasureObjects) DecomTieredObject(ctx context.Context, bucket, object string, fi FileInfo, opts ObjectOptions) error {
	if opts.UserDefined == nil {
		opts.UserDefined = make(map[string]string)
	}

	SkipRebalancing bool

	SrcPoolIdx int // set by PutObject/CompleteMultipart operations due to rebalance; used to prevent rebalance src, dst pools to be the same

	DataMovement bool // indicates an going decommisionning or rebalacing

	PrefixEnabledFn func(prefix string) bool // function which returns true if versioning is enabled on prefix

	// IndexCB will return any index created but the compression.