HP 6100 HP StorageWorks 4x00/6x00/8x00 Enterprise Virtual Array Updating Produ - Page 28

Description, Counter, Sample virtual disk statistics display

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Figure 6 Sample virtual disk statistics display . Table 3 HP Command View EVAPerf virtual disk statistics Counter Read Hit Req/s Read Hit MB/s Read Hit Latency Read Miss Req/s Read Miss Data Rate Read Miss Latency Write Req/s Write Data Rate Write Latency Flush Data Rate Description 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. The rate at which data is read from the array cache memory because of read hit requests. The average time it takes to complete a read request (from initiation to information receipt) from the array cache memory. The number of read requests (per second) that failed to complete from the array cache memory and were completed from physical disks instead. The rate at which data is read from physical disks because the data was not present in the array cache memory. The average time it takes to complete a read request (from initiation to information receipt) from the physical disks. 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. 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. This average time it takes to complete a write request (from initiation to receipt of write completion). 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. 28 Pre-upgrade tasks

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Figure 6 Sample virtual disk statistics display
.
Table 3 HP Command View EVAPerf virtual disk statistics
Description
Counter
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
Pre-upgrade tasks
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