MSS Efficiency Data

Explanation of Metrics for MSS Efficiency

1. Total Rate - The total volume of data transferred divided by the number of seconds that a drive is occupied serving the request. This includes mounting and positioning time, data transfer time and unmounting time. It is expressed in MB/s.

2. File Size - The average file size in MB transferred to or from the tape drive. The performance of tape drives varies according to the file size. The larger the file size, the higher the drive performance since it is able to achieve full data streaming. Smaller file sizes require the drive to stop/start more frequently, reducing performance as well as increasing wear and tear on the drives and tapes.

3. Tape Repeat Mounting - The remounting metrics track the average number of times a tape is mounted for all of the tapes which were touched that day. When the migration and recalling strategies are working well, this should be a low number. A tape mount and positioning takes between 3 and 5 minutes and the tape drive is not being used for data transfer during this period so a large number of repeat mounting wastes potential data transfer time. For example, if 10 tapes were touched in that day. One of the tapes were mounted 5 times and the rest only once, the total mounts were: 9 + 5 = 14. So the answer is 14/10 = 1.4. So Tape Repeat Mounting is 1.4.

4. Data Transferred / Mount - The volume of data in MB transferred on average for mounts during the day. Higher values indicate that the work for mounting is being effectively used.

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