CBR Indexing : FileNotFoundException

When do the CBR indexing, got this error in p8 trace log as below. The reason is document injecting is slower than indexing.  We got the FileStorage I/O bottleneck issue, or it can be resolved by optimizing indexing.

/gpfs/gpfsdev/icf_contentfiles/content/FN0/FN7/28E9F203-84FA-4809-871E-4977D32B654D{BEA940A5-1480-4150-BF72-96ADD540F595}0 (No such file or directory)\n at com.filenet.engine.content.RetryableFileIO.getExistingFileInputStream(RetryableFileIO.java:109)\n at com.filenet.engine.cbr.br.CBRFileInfo.fetchContentTypeResult(CBRFileInfo.java:337)\n at com.filenet.engine.cbr.br.CBRFileInfo.<init>(CBRFileInfo.java:274)\n at com.filenet.engine.cbr.spi.IndexHandle.init(IndexHandle.java:760)\n at com.filenet.engine.cbr.spi.IndexHandle.<init>(IndexHandle.java:429)\n at com.filenet.engine.cbr.spi.CSEIndexProcessor.processRequestList(CSEIndexProcessor.java:1672)\n at com.filenet.engine.cbr.spi.CSEIndexProcessor.submitRequestsForOneIndex(CSEIndexProcessor.java:1161)\n at com.filenet.engine.cbr.spi.CSEIndexProcessor.getAndProcessBatches(CSEIndexProcessor.java:730)\n at com.filenet.engine.cbr.spi.CSEIndexProcessor.indexRequests(CSEIndexProcessor.java:418)\n at com.filenet.engine.cbr.CBRExecutor.execute(CBRExecutor.java:187)\n at com.filenet.engine.tasks.BackgroundTask.safeExecute(BackgroundTask.java:248)\n at com.filenet.engine.tasks.BackgroundTask$BackgroundTaskPriviledgedExceptionAction.run(BackgroundTask.java:1036)\n at com.filenet.engine.context.CallState.doAsSystem(CallState.java:417)\n at com.filenet.engine.tasks.BackgroundTask.run(BackgroundTask.java:204)\n at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:908)\n at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:931)\n at java.lang.Thread.run(Thread.java:773)\nCaused by: java.io.FileNotFoundException: