errDecommissionRebalanceAlreadyRunning = errors.New("Decommission cannot be started, rebalance is already in progress")
)

func (a adminAPIHandlers) StartDecommission(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()

	objectAPI, _ := validateAdminReq(ctx, w, r, policy.DecommissionAdminAction)
	if objectAPI == nil {
		return
	}

	if len(indices) == 0 {
		return errInvalidArgument
	}

	if z.SinglePool() {
		return errInvalidArgument
	}

	// 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.

			adminRouter.Methods(http.MethodPost).Path(adminVersion+"/pools/decommission").HandlerFunc(adminMiddleware(adminAPI.StartDecommission, traceAllFlag)).Queries("pool", "{pool:.*}")
			adminRouter.Methods(http.MethodPost).Path(adminVersion+"/pools/cancel").HandlerFunc(adminMiddleware(adminAPI.CancelDecommission, traceAllFlag)).Queries("pool", "{pool:.*}")