Migration from existing master-master scenario, but wsrep_sst_xtrabackup extremely slow

Dear all,

I have a master-master scenario below:

DB1: 10.1.1.33
DB2: 10.1.1.34
MON running garbd: 10.1.1.111 (garbd -a gcomm://10.1.1.33:4567 -g blah)

DB1: running Percona Cluster with XtraDB

While DB2 restart running MySQL by using Percona Cluster with XtraDB and MON running garbd, now this cluster has 3 nodes.

And DB2 is resyncing because of the cluster is not synced.
But, the resyncing speed is extremely slow (about 3KB/s)

From: http://forum.percona.com/index.php?t=msg&goto=8884&
I noticed that the ibdata is being read and write simutaneously, seems the main problem of resyncing slow.

Is there any way to speed up resyncing ?
Or is there any correct way to migrate existing master-master scenario to Percona XtraDB cluster?

Thanks a lot

stephon

And that using xtrabackup results the same situation.
the cluster sync rate also in 3~4KB/s

or is there a better way to switch MySQL multi-master scenario to Percona cluster?

Thanks a lot