DFSMSdss was unable to read the high relative page number due to I/O errors. Therefore, DFSMSdss was unable to determine how much of the data set was actually used. If this error occurs during a logical DUMP or a COPY, all of the allocated space for the data set will be dumped or copied. If this error occurs during RESTORE processing, to a target device that has a different track capacity than the source device, there can be allocation problems because of residual data. It is therefore a good idea to restore the data set to a like device. If this error occurs during RELEASE processing, no space is released because the amount of releasable space cannot be determined.