eG Monitoring
 

Measures reported by IGELDiskActivityTest

This test reports statistics pertaining to the input/output utilization of each physical disk on each IGEL Endpoint.

Outputs of the test :One set of results for every combination of IGEL Endpoint:disk_partition

The measures made by this test are as follows:

Measurement Description Measurement Unit Interpretation
Percent_busy Indicates the percentage of elapsed time during which the disk is busy processing requests (i.e., reads or writes). Percent Comparing the percentage of time that the different disks are busy, an administrator can determine whether load is properly balanced across the different disks.

The detailed diagnosis of this measure provides information such as the Process IDs executing on the disk, the Process names, the rate at which I/O read and write requests were issued by each of the processes , and the rate at which data was read from and written into the disk by each of the processes. In the event of excessive disk activity, the details provided in the detailed diagnosis page will enable users to figure out which process is performing the I/O operation that is keeping the disk busy.
Percent_disk_reads Indicates the percentage of elapsed time that the selected disk drive is busy servicing read requests. Percent  
Percent_disk_writes Indicates the percentage of elapsed time that the selected disk drive is busy servicing write requests. Percent  
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  
Avg_queue_length Indicates the average number of both read and write requests that were queued for the selected disk during the sample interval. Number  
Current_queue_length The number of requests outstanding on the disk at the time the performance data is collected. Number This measure includes requests in service at the time of the snapshot. This is an instantaneous length, not an average over the time interval. Multi-spindle disk devices can have multiple requests active at one time, but other concurrent requests are awaiting service. This counter might reflect a transitory high or low queue length, but if there is a sustained load on the disk drive, it is likely that this will be consistently high. Requests experience delays proportional to the length of this queue minus the number of spindles on the disks. This difference should average less than two for good performance.
Read_rate Indicates the number of reads happening on a logical disk per second. Reads/Sec A dramatic increase in this value may be indicative of an I/O bottleneck on the IGEL Endpoint.
Data_read_rate 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 IGEL Endpoint.
Write_rate Indicates the number of writes happening on a local disk per second. Writes/Sec A dramatic increase in this value may be indicative of an I/O bottleneck on the IGEL Endpoint.
Data_write_rate 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 IGEL Endpoint.
Service_time Indicates the average time that this disk took to service each transfer request ( i.e., the average I/O operation time. Seconds 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.
Queue_time Indicates the average time that transfer requests waited idly on queue for this disk. Seconds Ideally, the value of this measure should be low.
Queue_time Indicates the average time that transfer requests waited idly on queue for this disk. Seconds Ideally, the value of this measure should be low.
IO_time Indicates the average time taken for read and write operations of this disk. Seconds The value of this measure is the sum of the values of the Service_timeand Queue_time measures.

A consistent increase in the value of this measure could indicate a latency in I/O processing.
Avg_io_read_size Indicates the average number of bytes transferred from disk during read operations. KB Larger I/Os tend to have higher latency (for example, BACKUP/RESTORE operations issue 1 MB transfers by default).
Avg_io_write_size Indicates the average number of bytes transferred into disk during write operations. KB Larger I/Os tend to have higher latency (for example, BACKUP/RESTORE operations issue 1 MB transfers by default).
Split_io Reports the rate at which the operating system divides I/O requests to the disk into multiple requests. Splits/Sec A split I/O request might occur if the program requests data in a size that is too large to fit into a single request or if the disk is fragmented. Factors that influence the size of an I/O request can include application design, the file system, or drivers. A high rate of split I/O might not, in itself, represent a problem. However, on single-disk systems, a high rate for this counter tends to indicate disk fragmentation.