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Measures reported by HPEvaVDiskTest
LUN is a Logical Unit Number. A LUN represents a logical abstraction or, if you prefer, virtualization layer between the physical disk device/volume and the applications. They are also referred to as virtual disks. A virtual disk can also be a Snapshot, Snapclone, or replication volume. This test auto-discovers the LUNs on an EVA storage array, tracks the I/O requests to each LUN, and reveals how well the cache services these requests.
The measures
made by this test are as
follows:
| Measurement |
Description |
Measurement
Unit |
Interpretation |
| Read_hit_requests |
Indicates the rate at which requests to the LUN were serviced by cache.
|
Reqs/Sec |
The detailed diagnosis of this measure reveals the LUN group to which this LUN belongs.
|
| Read_hit_data |
Indicates the rate at which this LUN read data from the cache. |
MB/Sec |
|
| Read_hit_latency |
Indicates the time taken by this LUN for reading from the cache. |
Ms |
A high value could indicate an I/O bottleneck.
|
| Read_miss_requests |
Indicates the rate at which read requests to the LUN were serviced by the disk and not the cache. |
Reqs/Sec |
Ideally, this rate should be low. A high rate indicates a large number of direct disk accesses, which in turn may expose the physical disk to overuse, and may increase the processing overheads.
|
| Read_miss_data |
Indicates the rate at which data was read from the physical disk and not the cache. |
MB/Sec |
| Read_miss_latency |
Indicates the time taken by this test for reading from the physical disk. |
Ms |
|
| Write_requests |
Indicates the rate at which write requests were serviced by vDisk. |
Reqs/Sec |
|
| Data_writes |
Indicates the rate at which data was written to the disk. |
MB/Sec |
|
| Write_latency |
Indicates the time taken for writing to the disk. |
Ms |
A high value could indicate an I/O bottleneck.
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