HP EVA physical disk group

•Read Latency—The amount of time it takes to complete a read request (from initiation to information receipt) through a host port. The time is an average of the read request latency for all virtual disks accessed through this port, and includes cache hits and misses.

•Write Req/s—The number of write requests (per second) completed from each host port.

•Write MB/s—The rate at which data is written from each host port.

•Write Latency—The amount of time it takes to complete a write request (from initiation to information receipt) through a host port. The time is an average of the write request latency for all virtual disks accessed through this port.

•Average Queue Depth—The average number of outstanding host requests against all virtual disks accessed through this host port. This number includes all host-initiated commands, including non-data transfer commands.

HP EVA physical disk

The physical disk performance object reports information on each physical disk on the system that is or has been a member of a disk group. These counters record all the activity to each disk and include all disk traffic for a host data transfer, as well as internal system support activity. This activity includes metadata updates, cache flushes, prefetch, sparing, leveling, snapclone and snapshot support, and redundancy traffic. Metrics for each controller are reported separately. Therefore, the total activity to each disk is the sum of activity to both controllers. The ID of each disk is from an internal representation and is not definitive for disk identification.

The counters are:

•Drive Queue Depth—The number of all active requests to each disk in the disk group, over all the disks in the disk group.

•Drive Latency—The amount of time from a data transfer command is sent to a disk to a command completion notification is returned from the disk. The time is not separated into read and write latencies. Completion of a disk command does not necessarily imply host request completion, because the request to a specific physical disk can be part of a larger request operation to a virtual disk. On the HSV100 series of controllers, average latency (the average of read and write latencies) is reported. Starting with the HSV200 series of controllers, separate metrics are provided for read and write latency.

•Read Req/s—The number of read requests (per second) sent to physical disks.

•Read MB/s—The rate at which data is read (per second) from physical disk.

•Read Latency—The average time it takes for a disk to complete a read request.

•Write Req/s—The number of write requests (per second) sent to physical disks.

•Write MB/s—The amount of data written (per second) to physical disks.

•Write Latency—The amount of time it takes for a disk to complete a write request.

The HP EVA physical disk group object provides information about physical disk activity per disk group. For each disk group, metrics are reported that represent the averages of various counters across all the disks in the disk group. The counters record all activity to the disks, including traffic for host data transfers and internal system support. This activity includes metadata updates, cache flushes, prefetch, sparing, leveling, snapclone and snapshot support, and redundancy traffic such as parity reads and writes or mirror copy writes. Each controller’s activity is reported separately, so the total activity to each disk group is the sum of both controllers’ activity.

For each counter, the results are an average of all disks in the disk group.

Using the graphical user interface