Dell EMC Unity: Multiprotocol batch jobs failing since migration to Unity from VNX due to file locking (User Correctable)

Migration from VNX to Dell EMC Unity Platform.

Multiprotocol batch jobs failing since migration to Unity from VNX due to file locking

Unity uses a different default policy for locking in Multiprotocol environments, this can affect some operations that previously ran on VNX and used the VNX default nolock locking policy for Multiprotocol environments.


Unity File system locking policies
SMB and NFS have their own lock range. Protocol specifications define lock ranges as mandatory for SMB but may be advisory for NFS. NFSv3/v3 uses a separate protocol (NLM) that is always advisory. NFSv4 has the lock management integrated in the protocol itself, but may also be advisory or mandatory, depending of the implementation.

A locking policy property is used to define the alternate behavior. You can select one of the following locking policies for a multiprotocol file system:

 

Setting	Description
Mandatory (Default)	Uses the SMB and NFSv4 protocols to manage range locks for a file that is in use by another user. A mandatory locking policy prevents data corruption if there is concurrent access to the same locked data.
Advisory	In response to lock requests, reports that there is a range lock conflict, but does not prevent access to the file. This policy allows NFSv3 applications that are not range-lock compliant to continue working, but risks data corruption if there are concurrent writes.

VNX File System Locking Policies
 

nolock	wlock	rwlock
No locks: Treats all locks as advisory for NFS (v2 or v3) clients (default setting, least secure)	Write lock: Enforces CIFS or NFSv4 write locks for NFSv2 or NFSv3 client access.	Read/write lock: Enforces CIFS or NFSv4 read and write locks for NFSv2 or NFSv3 client access (most secure).
Lock requests: If a CIFS or NFS client locks a file, no other client can lock that file.	Lock requests: If a CIFS or NFS client locks a file, no other client can lock that file.	Lock requests: If a CIFS or NFS client locks a file, no other client can lock that file.
Access requests:	Access requests:	Access requests:
CIFS clients ignore locks set by NFS. NFSv2 or NFSv3 clients can read and write to files locked by CIFS or NFSv4.	CIFS clients denying concurrent access for write cannot open files locked by NFS for exclusive access. NFSv2 or NFSv3 clients can read but cannot write to or delete, files locked by CIFS or NFSv4	CIFS clients denying concurrent access for read or write cannot open files locked by NFS for exclusive or shared access. NFSv2 or NFSv3 clients cannot read, write, or delete files locked by CIFS.

Documentation Reference: Managing a Multiprotocol Environment on VNX

The user should consider changing the locking Policy on MP File Systems to Advisory from Unity Default of Mandatory

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