xtrabackup too slow, The copying transaction log migh be overtaken already by the target

After changing the transactions in my app, my innodb binlog is increasing fast than before change.

Now I have getting error in my backups and it never ends. Before backup take about 3,5 hours or so and now after 7 hours it has taken about 25% of total backup size.

I have tried with version 1.6.4 and 2.0.2 and the error is:
Version 1.6.4:

###Warning###: The copying transaction log migh be overtaken already by the target.
: Waiting log block no 80669053, but the bumber is already 84765037.
: If the number equals 80669053 + n * 2047992, it should be overtaken already

Version 2.0.2:
xtrabackup: error: log block numbers mismatch:
xtrabackup: error: expected log block no. 410098410, but got no. 412146402 from the log file.
xtrabackup: error: it looks like InnoDB log has wrapped around before xtrabackup could process all records due to either log copying being too slow, or log files being too small.
xtrabackup: Error: xtrabackup_copy_logfile() failed.

Why is it running so slow ?

I need to explain that I have already increased the size of binlog from 100MB to 500MB and from 500MB to 1GB. The result is always the same

OK, this was caused by a problem with io troughput