Xtrabackup 2.0 stalling near the end of making a full snapshot, causing replication stall

I am running Percona 5.1 server and trying to make full snapshots using xtrabackup 2.0 (the GA release)

The snapshot behaves fine until near the end. Then the Disk IO crawls to near stop, and replication (I run this on a dedicated replication slave) seems not to run any queries…this goes on for hours with the transaction log stuck at the same position until I kill the job.

I am using ‘parallel=100’ which was the setting back with 1.6.5 with no problem.

OS verions: Debian Lucid Lenny
MySQL version: Percona 5.1 (tried this on 2 diff minor versions with same symptom)