diff --git a/src/main/java/com/amazon/opendistroforelasticsearch/ad/ml/CheckpointDao.java b/src/main/java/com/amazon/opendistroforelasticsearch/ad/ml/CheckpointDao.java
index f4c41de3..d6c388e4 100644
--- a/src/main/java/com/amazon/opendistroforelasticsearch/ad/ml/CheckpointDao.java
+++ b/src/main/java/com/amazon/opendistroforelasticsearch/ad/ml/CheckpointDao.java
@@ -151,8 +151,10 @@ public CheckpointDao(
         this.clock = clock;
         this.checkpointInterval = checkpointInterval;
         this.indexUtil = indexUtil;
+        // each checkpoint with model initialized is roughly 250 KB if we are using shingle size 1 with 1 feature
+        // 1k limit will send 250 KB * 1000 = 250 MB
         this.maxBulkRequestSize = maxBulkRequestSize;
-        // 1 bulk request per minute. 1 / 60 seconds = 0. 02
+        // 1 bulk request per 1/bulkPerSecond seconds.
         this.bulkRateLimiter = RateLimiter.create(bulkPerSecond);
     }
 
@@ -283,6 +285,10 @@ private void flush(BulkRequest bulkRequest) {
         clientUtil.<BulkRequest, BulkResponse>execute(BulkAction.INSTANCE, bulkRequest, ActionListener.wrap(r -> {
             if (r.hasFailures()) {
                 requests.addAll(BulkUtil.getIndexRequestToRetry(bulkRequest, r));
+            } else if (requests.size() >= maxBulkRequestSize / 2) {
+                // during maintenance, we may have much more waiting in the queue.
+                // trigger another flush if that's the case.
+                flush();
             }
         }, e -> {
             logger.error("Failed bulking checkpoints", e);
diff --git a/src/main/java/com/amazon/opendistroforelasticsearch/ad/transport/EntityResultTransportAction.java b/src/main/java/com/amazon/opendistroforelasticsearch/ad/transport/EntityResultTransportAction.java
index 655b1feb..cbf23734 100644
--- a/src/main/java/com/amazon/opendistroforelasticsearch/ad/transport/EntityResultTransportAction.java
+++ b/src/main/java/com/amazon/opendistroforelasticsearch/ad/transport/EntityResultTransportAction.java
@@ -93,7 +93,8 @@ public EntityResultTransportAction(
     @Override
     protected void doExecute(Task task, EntityResultRequest request, ActionListener<AcknowledgedResponse> listener) {
         if (adCircuitBreakerService.isOpen()) {
-            listener.onFailure(new LimitExceededException(request.getDetectorId(), CommonErrorMessages.MEMORY_CIRCUIT_BROKEN_ERR_MSG));
+            listener
+                .onFailure(new LimitExceededException(request.getDetectorId(), CommonErrorMessages.MEMORY_CIRCUIT_BROKEN_ERR_MSG, false));
             return;
         }