dd error on cluster, installing oracle 10g

Hi, I'm trying to install Oracle 10G on two nodes with OS AIX 5.3, using emc storage and powerpath 5.3

when I execute the next command at same time, on both nodes, I'm receving the next error:

{node1:root}/ -> dd if=/dev/zero of=/dev/ora_vote_raw bs=8192 count=25000
25000+0 records in.
25000+0 records out.

{node2:root}/ -> dd if=/dev/zero of=/dev/ora_vote_raw bs=8192 count=25000
dd: 0511-053 The write failed.
: The requested resource is busy.

This is the procedure executed on both nodes

1. Install EMC ODM drivers

2. run cfgmgr to detect devices

3. Install PowerPath version 5.3

4. register PowerPath
{node1:root}/ -> emcpreg –install

5. initialize PowerPath devices
{node1:root}/ -> powermt config

6. save PowerPath configuration
{node1:root}/ -> powermt save

7. Identify hdiskpower devices for ocr and voting disk

{node1:root}/ -> ls -la /dev/rhdiskpower0
crw-rw----    1 root     system       45,  0 Jun 01 10:17 rhdiskpower0

{node1:root}/ -> ls -la /dev/rhdiskpower10
crw-rw----    1 root     system       45, 10 Jun 01 10:17 rhdiskpower10

8. Create a device on each node for ocr and voting disk.

{node1:root}/ -> mknod /dev/ora_ocr_raw c 45 0

{node1:root}/ -> mknod /dev/ora_vote_raw c 45 10

9. configure the reserve_lock, attribute must be set to "no"
{node1:root}/ -> chdev -l hdiskpower0 -a reserve_lock=no
{node1:root}/ -> chdev -l hdiskpower10 -a reserve_lock=no

10. Verify the attribute is set
{node1:root}/ -> lsattr –El hdiskpower0
{node1:root}/ -> lsattr –El hdiskpower10