HP StorageWorks Enterprise Virtual Array Updating Product Software Guide (XCS 09534000) (5697-0754, October 2010)

Figure 7 Sample virtual disk statistics display
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Table 3 HP Command View EVAPerf virtual disk statistics
DescriptionCounter
The number of read requests per second completed from the array cache
memory. Data may reside in the cache memory due to a previous cache miss
or because of a prefetch operation generated by a sequential read data stream.
Read Hit Req/s
The rate at which data is read from the array cache memory because of read
hit requests.
Read Hit MB/s
The average time it takes to complete a read request (from initiation to informa-
tion receipt) from the array cache memory.
Read Hit Latency
The number of read requests (per second) that failed to complete from the array
cache memory and were completed from physical disks instead.
Read Miss Req/s
The rate at which data is read from physical disks because the data was not
present in the array cache memory.
Read Miss Data Rate
The average time it takes to complete a read request (from initiation to informa-
tion receipt) from the physical disks.
Read Miss Latency
The number of write requests per second completed to a virtual disk that were
received from all hosts. Write requests may include transfers from a source array
to this array for data replication and host data written to snapshot or snapclone
volumes.
Write Req/s
The rate at which data is written to the virtual disk by all hosts and includes
transfers from the source array to the destination array.
Write Data Rate
This average time it takes to complete a write request (from initiation to receipt
of write completion).
Write Latency
The rate at which data is written to a physical disk for the associated virtual
disk. The sum of flush counters for all virtual disks on both controllers is the rate
at which data is written to the physical drives and is equal to the total host write
data. Data written to the destination array is included. Host writes to snapshots
and snapclones are included in the flush statistics, but data flow for internal
snapshot and snapclone normalization and copy-before-write activity are not
included.
Flush Data Rate
Preparing for the upgrade30