adop fs_clone/prepare fails with [UNEXPECTED]Invalid worker Count: 0

We recently added a node to our current EBS application. As part of the node addition steps, tried to executed adop phase=fs_clone but it failed immediately with errors.


Enter the APPS password:
Enter the SYSTEM password:
Enter the WLSADMIN password:
Validating credentials.
Initializing.
    Run Edition context  : /app/EBD//fs2/inst/apps/EBD_oraapp01/appl/admin/EBD_oraapp01.xml
    Patch edition context: /app/EBD//fs1/inst/apps/EBD_oraapp01/appl/admin/EBD_oraapp01.xml
    Patch file system free space: 41.85 GB
Validating system setup.
    [UNEXPECTED]Invalid worker Count: 0
    [UNEXPECTED]Error validating worker count

Later tried to assign worker count of value 8 manually as below but it also failed
  $ adop phase=fs_clone workers=8
 
Validating credentials.
Initializing.
    Run Edition context  : /app/EBD//fs2/inst/apps/EBD_oraapp01/appl/admin/EBD_oraapp01.xml
    Patch edition context: /app/EBD//fs1/inst/apps/EBD_oraapp01/appl/admin/EBD_oraapp01.xml
    Patch file system free space: 41.85 GB
    [UNEXPECTED]Specified value 8 is not supported by the database.
    [UNEXPECTED]A maximum of 1 workers can be invoked.
    [UNEXPECTED]Error validating worker count

Observed the same issue with prepare phase as well.

Solution:
The default worker count information(recomm & max)  is stored in a file adpawc.xml that can be found under $APPL_TOP/admin/$TWO_TASK/log

Somehow this file has been modified with recommended value as 0 and max value as 1 during node addition.

FileContent:
<?xml version="1.0"?>
<WORKER_COUNT>
        <RECOMMENDED>0</RECOMMENDED>
        <MAX>1</MAX></WORKER_COUNT>

Update recommended &  max value based on cpu count.

Here I updated recommended value as 8 and max value as 64 and saved the file.

Once the changes are made, fs_clone went smoothly.