Disk Metrics

Reference information for Disk Metrics

In addition to these base metrics, many aggregate metrics are available. If an entity type has parents defined, you can formulate all possible aggregate metrics using the formula base_metric_across_parents.

In addition, metrics for aggregate totals can be formed by adding the prefix total_ to the front of the metric name.

Use the type-ahead feature in the Cloudera Manager chart browser to find the exact aggregate metric name, in case the plural form does not end in "s".

For example, the following metric names may be valid for Disk:

  • average_queue_length_across_clusters
  • total_average_queue_length_across_clusters

Some metrics, such as alerts_rate, apply to nearly every metric context. Others only apply to a certain service or role.

average_queue_length

Description
The average queue length of the requests issued to the disk. This is the same as the 'avgqu-sz' measure from iostat.
Unit
ios
Parents
cluster, host, rack
CDH Version
[CM -1.0.0..CM -1.0.0]

average_request_size

Description
The average size in sectors of the requests issued to the disk. This is the same as the 'avgrq-sz' measure from iostat.
Unit
sectors
Parents
cluster, host, rack
CDH Version
[CM -1.0.0..CM -1.0.0]

await_read_time

Description
The average time for read requests issued to the disk to be served. This includes the time spent by the requests in queue and the time spent servicing them. This is the same as the 'r_await' measure from iostat.
Unit
ms
Parents
cluster, host, rack
CDH Version
[CM -1.0.0..CM -1.0.0]

await_time

Description
The average time for requests issued to the disk to be served. This includes the time spent by the requests in queue and the time spent servicing them. This is the same as the 'await' measure from iostat.
Unit
ms
Parents
cluster, host, rack
CDH Version
[CM -1.0.0..CM -1.0.0]

await_write_time

Description
The average time for write requests issued to the disk to be served. This includes the time spent by the requests in queue and the time spent servicing them. This is the same as the 'w_await' measure from iostat.
Unit
ms
Parents
cluster, host, rack
CDH Version
[CM -1.0.0..CM -1.0.0]

read_bytes_rate

Description
The number of bytes read from the device
Unit
bytes per second
Parents
cluster, host, rack
CDH Version
[CM -1.0.0..CM -1.0.0]

read_ios_rate

Description
The number of read I/O operations issued to the device
Unit
ios per second
Parents
cluster, host, rack
CDH Version
[CM -1.0.0..CM -1.0.0]

service_time

Description
The average service time for requests issued to the disk. This is the same as the 'svctm' measure from iostat. Note the warning from iostat for this metric: Warning! Do not trust this field any more. This field will be removed in a future sysstat version.
Unit
ms
Parents
cluster, host, rack
CDH Version
[CM -1.0.0..CM -1.0.0]

utilization

Description
The percentage of CPU time during which I/O requests were issued to the device. This is the same as the 'util' measure from iostat.
Unit
percent
Parents
cluster, host, rack
CDH Version
[CM -1.0.0..CM -1.0.0]

write_bytes_rate

Description
The number of bytes written to the device
Unit
bytes per second
Parents
cluster, host, rack
CDH Version
[CM -1.0.0..CM -1.0.0]

write_ios_rate

Description
The number of write I/O operations issued to the device
Unit
ios per second
Parents
cluster, host, rack
CDH Version
[CM -1.0.0..CM -1.0.0]