Patent ID: 8566483

Claim:
A method for use in measuring data access activity in a data storage system, wherein the data storage system comprises data storage devices in a RAID group, the method comprising: capturing I/O data describing I/O activity for slices in the RAID group, wherein the I/O data describes I/O response time for the slices in the RAID group; based on the I/O data, determining a first value of data access activity for a first slice in the RAID group, wherein the first value of data access activity describes a first I/O response time corresponding to a first time period; based on the I/O data, determining a first average I/O response time for the RAID group comprising the first slice, wherein the first average I/O response time corresponds to the first time period; based on the first I/O response time and the first average I/O response time, determining a normalized first I/O response time; based on the I/O data, determining a second value of data access activity for the first slice in the RAID group, wherein the second value of data access activity describes a second I/O response time corresponding to a second time period; based on the I/O data, determining a second average I/O response time for the RAID group comprising the first slice, wherein the second average I/O response time corresponds to the second time period; based on the second I/O response time and the second average I/O response time, determining a normalized second I/O response time; and deriving, from the normalized first and second I/O response times, an exponential moving average of data access activity for the first slice.