Recovery of a VSAM data set has been in progress when either a deletion of the existing data set fails for a reason other than its catalog entry has not been found, or an allocation error has occurred. Message ARC1001I gives the base cluster name being recovered. For a deletion error, the reason code is the VSAM catalog return code, as documented by Message IDC3009I in z/OS MVS System Messages, Vol 6 (GOS-IEA). For an allocation error, the preceding message ARC0503E gives the base cluster name being allocated. Message ARC0503E also gives the return code, reason code, and information code from dynamic allocation. The reason code in preceding message ARC1001I is the return code from dynamic allocation.