REplication performance issue

[Chityphong Banchong <chityphong.banchong@xxxxxxxxxxx>]

Hi Guys,

I have a problem here with  my replication setting, it is really slow.   
I have setup a replication on 2 servers,  4Go memory, 3 HDD RAID0, 1 
quad core Xeon, Mysql 5. The replication is working fine.

The problem is that the performance drop really bad when I move the 
application from the single DB to the DB server with the replication on.

I did the benchmark on the DB with the replication on with sysbench, I 
got following result:


1- Benchmark on the table which is not replicated:

thread number: 16
transaction per second :  634.45
Wait IO (from top):         7.6
server Load:                   10

It is not fantastic but ok

2- Benchmark on the table which is replicated:

thread number: 16
transaction per second : 80.69 !!!!
wait IO (from top):         19.5
server Load:                  0.8

As you can see when use a tables that is replicated the performance drop 
badly 8x , the IO is slower, and the load of the server drop cause 
waiting for the IO.

Does anyone has face this problem before?  Is there any way to slow that ??

Thanks a lot in advance .