sorry. post again.. about write speed in mogilefs

[Eric Chang]

We launch mogilefs last week.
We use zeus's ZXTM process incomming resquest,
then pass to two perlbal and two web(php+mogilefsd tracker) and two
storage node (mogstored).
The mod_php node process incomming request and ask tracker get file
path and send reproxy
header back to perlbal.
Now they all work,but still have some questions:
1.Mogilefs database node , we only replicate data to another server,
but how to make they auto failover ? Is it possible ? How to do this
in livejournal ?
2.We provide blog service, and user post articles ,pictures , all
articles transfer to html and save to mogilefs, but we found the speed
of write to mogilefs so slow, about 10 times slow then write to local
filesystem( original way).
What's the problem ? How to enhenced the write speed?
All perlbal node (include mogstored ) already installed with IO::AIO.