Methods and systems for monitoring quality of service (QOS) data for a plurality of storage volumes from a storage operating system of a storage system are provided. A performance manager collects QOS data for a storage volume from among the plurality of storage volumes and the QOS data includes a response time in which the storage volume responds to an input/output (I/O) request; determines that the collected QOS data is noisy by comparing an average number of I/O requests processed within a time duration for the storage volume with a first threshold value; uses comparable QOS data of another storage volume for generating an expected range for future QOS data; and monitors QOS data for the storage volume for determining whether a current QOS data for the storage volume is within the expected range.