Two ZooKeepers cannot be started caused some HBASE regional servers cannot be started too

[a...@hsk.hk]

Hi,

I have 3 Zookeepers, 2 of them cannot be started:

./bin/zkServer.sh start
        JMX enabled by default
        Using config: /usr/local/ZooKeeper/bin/../conf/zoo.cfg
        Starting zookeeper ... STARTED

However when I used "ps axu | grep ZooKeeper", I found there was no any 
ZooKeeper running which caused some HBASE regional servers were not started.
Question: Any idea where is the log file of ZooKeeper if any? Or please advise 
what I should check?

Thanks