innobackupex fails with Errcode: 30 - Read-only file system nfs volume

Running innobackupex with nfs qtree as source and destination, backup fails with below error message

innobackupex: Can’t create/write to file /test/backup/.snapshot/db.opt’ (Errcode: 30 - Read-only file system)

[00] error: cannot open the destination stream for .snapshot/db.opt

[00] Error: backup file failed.

Failed to create file ./.snapshot/db.opt
Percona Version percona-xtrabackup-24-2.4.4-1.el6.x86_64

Mysql Version : 5.6.20

How to ignore the .snapshot hidden folder ? I have already tried with ignore_db_dirs . Still failed with same error.

mysql> show global variables like ‘ignore_db_dirs’;

±---------------±----------+

| Variable_name | Value |

±---------------±----------+

| ignore_db_dirs | .snapshot |

±---------------±----------+

Thanks
Suresh Rajagopal