Handling channel full exception

Hi ,
I have started the flume agent with spooling directory source and HDFS sink. how can i know whether connection to HDFS is succeed or not . i have configured log4j.properties to print only error message . when connection to HDFS failed log4j through this exception as WARN so i cannot get this exception when set log4j threshold as ERROR.at some point it lead to channel full exception
How can i find whether connection to HDFS is succeed or not ?
Thanks.