Disk Activity Test
When executed on Windows, Solaris, AIX, and HP-UX systems, this test reports statistics pertaining to the input/output utilization of each physical disk on a system.
Target of the test : Any host system
Agent deploying the test : An internal agent
Outputs of the test : One set of results for each host monitored
|
Measurement | Description | Measurement Unit | Interpretation |
---|---|---|---|
Disk read time: |
Indicates the average time in seconds of a read of data from the disk. |
Secs |
|
Disk write time: |
Indicates the average time in seconds of a write of data from the disk. |
Secs |
|
Disk read rate: |
Indicates the number of reads happening on a logical disk per second. |
Operations/Sec |
A dramatic increase in this value may be indicative of an I/O bottleneck on the server. |
Data read rate from disk: |
Indicates the rate at which bytes are transferred from the disk during read operations. |
KB/Sec |
A very high value indicates an I/O bottleneck on the server. |
Disk write rate: |
Indicates the number of writes happening on a local disk per second. |
Operations/Sec |
A dramatic increase in this value may be indicative of an I/O bottleneck on the server. |
Data write rate to disk: |
Indicates the rate at which bytes are transferred from the disk during write operations. |
KB/Sec |
A very high value indicates an I/O bottleneck on the server. |
Disk service time: |
Indicates the average time that this disk took to service each transfer request ( i.e., the average I/O operation time) |
Secs |
A sudden rise in the value of this measure can be attributed to a large amount of information being input or output. A consistent increase however, could indicate an I/O processing bottleneck. |
Disk queue time: |
Indicates the average time that transfer requests waited idly on queue for this disk. |
Secs |
Ideally, the value of this measure should be low. |
Disk I/O time: |
Indicates the avarage time taken for read and write operations of this disk. |
Secs |
The value of this measure is the sum of the values of the Disk service time and Disk queue time measures. A consistent increase in the value of this measure could indicate a latency in I/O processing. |
Note:
- For this test to report measures on Unix systems, the sysstat package must be installed on the server (check for the existence of the iostat command on the target system).
- If the sysstat version installed on the target server is less than 4.0.7, the following measures also will not be available – Data read rate from disk and Data write rate to disk.
- As the HPUX operating system only provides the overall transfer rate to and from the disk, the eG agent reports this value for both the Disk read rate and the Disk write rate. Likewise, the Data read rate from disk and Data write rate to disk are also reported as the same values (i.e., equal to the data transfer rate from the disk). Likewise, the Disk read time and Disk write time are also reported as the same values (i.e., equal to the seconds per average seek).
- Detailed diagnosis will not be available for systems operating on HPUX platforms.