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# Disk Technology metrics

Unisphere collects and displays metrics for disk technologies.

Within the PM metrics section, V4 is used to denote that the metric is supported only by a storage system (array) running PowerMaxOS 10 (6079). V3 is used to denote that the metric is supported only by a storage system (array) running HYPERMAX OS 5977 or PowerMaxOS 5978. Metrics without the denotation are supported by all storage systems (arrays).

The following table lists all metrics that are available for disk technologies.

Table 1. Disk technology metrics
Metric | Description
--- | ---
% Busy | The percentage of time that the disk group is busy serving I/Os
% Free Capacity | The percentage of the disk group capacity that is free
% Idle | The percentage of time the disk group is idle
% Used Capacity | The percentage of the disk group capacity that is allocated
Avg Read Size (KB) | The average number of kilobytes for a single read command
Avg Write Size (KB) | The average number of kilobytes for a single write command
IO Density | The number of BE requests per GB of disk. (BE Reads + BE Writes) /allocated capacity
IOs/sec | The total number of read and write I/Os per second
Number of Spare Hypers | Number of spare hypers (V4)
Read RT | The average time that it took the disk group to serve one read command
Reads/sec | The number of reads per second for the disk group
Rebuild Blocks Read/sec | The rebuild blocks read (V4)
Rebuild Blocks Written/sec | The rebuild blocks written (V4)
Response Time | The average time that it took the disk group to service I/Os
Throughput | The total number of MBs per second for the disk group
Throughput Read | The read throughput (MBs) of the disk group per second
Throughput Written | The write throughput (MBs) of the disk group per second
Total Capacity | The total capacity (in GB) of all the disks in the disk group
Total SCSI Commands/sec | The total number of read commands, write commands, skip mask commands, verify commands, XOR write commands, and XOR write-read commands performed by the disk group each second
Unmap Command Count | Unmap command count
Used Capacity (GB) | The total capacity (in GB) allocated for all the disks in the disk group
Write RT | The average time that it took the disk group to serve one write command
Writes/sec | The number of writes per second for the disk group