VAN0591E: READ OF VTOC ON VOL=xxxx FAILED. RC=00000004 CVAF stat=49

Products

• Vantage Storage Resource Manager

Issue/Introduction

For some weeks now, from time to time, DTOC4SYS data becomes unavailable and the Vantage Host (SAMS) STC is reporting several errors / system abends.

After recycling the STC it works again for a while. The SAMS log has the following errors.

The SAMS STC log has the following errors.
VAN0591E: READ OF VTOC ON VOL=xxxx FAILED. RC=00000004 CVAF stat=49         

Resolution

Vantage is trying to read information from the volumes, but can't. This looks internal to the volumes themselves.  The sysprog might want to check some of these volumes, and any IGGN311E messages, etc. May need to contact IBM if the problem persists.

The customer was able to resolve the VAN0591E messages by removing unneeded uncataloged data sets from the volumes getting the error. 

Additional Information

The combination of RC=00000004 (Return Code 4) and CVAF stat=49 (Catalog Volume Access Method status) generally indicates a warning or minor error condition during a catalog operation [1.1, 1.11].
Specifically, CVAF status 49 indicates that a parameter area storage obtain request failed, or in some contexts, it indicates a "DEF DREFOFF" failure where the specified area is incorrect [1.1, 1.4].
Key Details:
RC=4: Usually indicates a warning, a successful operation with an exception, or that the requested data was not found, but the overall operation was not a fatal error [1.1, 1.3].
CVAF Stat 49: Points to an issue with memory management (storage) or a specific parameter error within the Catalog Volume Access Method [1.4].
Context: These codes typically appear in z/OS DFSMStvs or Catalog management diagnostic logs [1.11, 1.14]. 
Action Required:
If this error is recurring, it is recommended to review the specific IGGN311E message or the surrounding diagnostics to identify the invalid dataset format or specific parameter error [1.11].