High amount of data to be processed

Hi,

maybe you have an idear:

We have clients with 6 or more subclients. The Client is using windows file backup agent.  Al jobs are shown completed and no failed files or folders. But sometimes we getting this message:

ERROR CODE [7:331]: High amount of data to be processed in FailedFilesRetry phase is observed with bulk of the data coming from big files that can be more efficiently processed by enabling optimized backups via extent level. Review documentation to proceed.Source: XYZ, Process: clBackup (Error Lookup Site: http://kb.commvault.com/#!/?q=%227:331%22)

For some subclients it is daily for the subclients its random. And all subclients are very small maybe they have 20Gb inc change rate.