In versions earlier than 5.7.1, if the HDLM driver fails to allocate memory for an I/O operation when reading or writing from the HDLM device, it returns an error instead of retrying.
In version 5.7.1 or later, the system tries to allocate the memory again and the I/O operation is executed successfully. The number of retries can be set by the user. By default, the system retries the operation until memory is allocated.