Poll Interval, Msecs To wait before modification checks & Queue Name in CC

Question

Hi All,
I have 3 inter-related interfaces which is having 3 File Sender Communication channels as below charasteristics;
All 3 ccs are running on a common Queue Name inorder to cater the business scenario;
so PI should consume the files in the same sequance of files are copping into the locations;
(time gap between incoming files is around 1-3 secs)
Existing Values in Production system
IF086
Poll Interval                                                                        1 secs
Msecs To wait before modification checks                      10000
Queue Name                                                                     XI_QUE1
run sequance must be 1
IF913
Poll Interval                                                                        1 secs
Msecs To wait before modification checks                      10000
Queue Name                                                                     XI_QUE1
run sequance must be 2
IF084
Poll Interval                                                                        1 secs
Msecs To wait before modification checks                      10000
Queue Name                                                                     XI_QUE1
run sequance must be 3
we are having PI Alert email configured in the system;
when we get a big files into the locations, we get an unwanted Alert emails saying Error;
when I check PI, Overall file transfer is successful,
but we have the below error in the Message Display Audit log as
"Channel CC_Cxxx: Attempt to send file 'T201_200909141702' failed because file was modified during processing. 0 bytes expected, 1202248 bytes found. Trying to resend file" 
but Overall file transfer is successful;
Does anyone can explain the reason for this error; ?
Also to remove this error & unwanted Alert email (since final status is successfull), I changed the Poll Interval to 3 for all 3 above CCs; Now I dont get the above error;
Do you think there might be a sequance issue due to this change;?
(time gap between incoming files is around 1-3 secs)
quite lengthy to explain sorry;
Appreciate your help please
thanks
Iver

Answer 1

Hello Iver
Question 3 in the note #821267 FAQ: XI 3.0 / PI 7.0/ PI 7.1 File Adapter, explains what is happening here. This answers your first question.
The file in question was being written to by another process when the file adapter attempted to send it. Depending on the length of time/amount of data that is being written to these files, increasing the polling interval to 3 seconds will help.
Regards
Mark