Disk

Documentation for disk performance metrics.

Metrics

disk.ioInProgress

The number of I/O operations currently in progress. The metric is incremented as requests are submitted and decremented as requests finish. The metric does not include requests that are in queue waiting to be submitted.

Min	Max	Units	Metric Type	Data Type
0	MAX_UNSIGNED_LONG	I/O	raw	integer

disk.readsIssued

The number of reads completed successfully.

Min	Max	Units	Metric Type	Data Type
0	MAX_UNSIGNED_LONG	reads	raw	count

disk.readsMerged

The number of adjacent reads merged for read efficiency. For example, two 4K reads may become one 8K read before being ultimately handed to the disk. The merged read will be queued (and counted) as only one I/O.

Min	Max	Units	Metric Type	Data Type
0	MAX_UNSIGNED_LONG	reads	raw	count

disk.sectorsRead

The number of sectors read successfully.

Min	Max	Units	Metric Type	Data Type
0	MAX_UNSIGNED_LONG	sectors	raw	count

disk.sectorsWritten

The number of sectors written successfully.

Min	Max	Units	Metric Type	Data Type
0	MAX_UNSIGNED_LONG	sectors	raw	count

disk.timeDoingIO

The number of milliseconds spent processing IO requests. This metric only increases when the number of I/Os in progress is nonzero.

Min	Max	Units	Metric Type	Data Type
0	MAX_UNSIGNED_LONG	ms	raw	time

disk.timeReading

The number of milliseconds spent by all reads.

Note: A possibility exists that this value will overflow and wrap on a 32-bit system that has been continuously running for an extended time.

Min	Max	Units	Metric Type	Data Type
0	MAX_UNSIGNED_LONG	ms	raw	time

disk.timeWriting

The number of milliseconds spent by all writes.

Note: A possibility exists that this value will overflow and wrap on a 32-bit system that has been continuously running for an extended time.

Min	Max	Units	Metric Type	Data Type
0	MAX_UNSIGNED_LONG	ms	raw	time

disk.writesCompleted

The number of writes completed successfully.

Min	Max	Units	Metric Type	Data Type
0	MAX_UNSIGNED_LONG	writes	raw	count

disk.writesMerged

The number of adjacent writes merged for write efficiency. For example, two 4K writes may become one 8K write before being ultimately handed to the disk. The merged write will be queued (and counted) as only one I/O.

Min	Max	Units	Metric Type	Data Type
0	MAX_UNSIGNED_LONG	writes	raw	count

disk.weightedTimeDoingIO

The weighted amount of time processing I/Os that is incremented every time the number of I/Os in progress is updated. The stepwise increment is equal to the number of I/Os in progress multiplied by the number of milliseconds spent doing I/Os since the last time number of I/Os in progress was updated. This can provide an easy measure of both I/O completion time and the backlog that may be accumulating.

Min	Max	Units	Metric Type	Data Type
0	MAX_UNSIGNED_LONG	ms	raw	time

disk.size

The total size of the file system.

Min	Max	Units	Metric Type	Data Type
0	null	GB	raw	numeric

disk.used

The amount of disk space allocated to existing files in the file system.

Note: The maximum value is the total size of the file system.

Min	Max	Units	Metric Type	Data Type
0	null	GB	raw	numeric

disk.available

The amount of space available within the file system for the creation of new files by unprivileged users. When this value is less than or equal to zero, it will not be possible to create any new files on the file system without first deleting others, unless the process has appropriate privileges.

Note: The maximum value is the total size of the file system. The minimum value can be less than 0.

Min	Max	Units	Metric Type	Data Type
null	null	GB	raw	numeric

disk.spaceUtilization

The disk space utilization (used storage divided by total size) for an individual disk.

Min	Max	Units	Metric Type	Data Type
0	1	utilization	derived	percentage

disk.spaceUtilizationAverage

The average disk space utilization (used storage divided by total size) across all disks.

Min	Max	Units	Metric Type	Data Type
0	1	utilization	derived	percentage

disk.timeUtilization

The disk time utilization (time spent doing I/O operations in a measurement interval divided by that interval) for an individual disk.

Min	Max	Units	Metric Type	Data Type
0	1	utilization	derived	percentage

disk.timeUtilizationAverage

The average disk time utilization (time spent doing I/O operations in a measurement interval divided by that interval) across all disks.

Min	Max	Units	Metric Type	Data Type
0	1	utilization	derived	percentage

disk.readRate

The amount of data read divided by the time spent reading on an individual disk since the last reboot.

Min	Max	Units	Metric Type	Data Type
0	null	MB/s	derived	numeric

disk.readRateAverage

The average of data read divided by time spent reading across all disks since the last reboot.

Min	Max	Units	Metric Type	Data Type
0	null	MB/s	derived	numeric

disk.writeRate

The amount of data written divided by the time spent writing on an individual disk since the last reboot.

Min	Max	Units	Metric Type	Data Type
0	null	MB/s	derived	numeric

disk.writeRateAverage

The average of data written divided by time spent writing across all disks since the last reboot.

Min	Max	Units	Metric Type	Data Type
0	null	MB/s	derived	numeric

disk.readWriteRatio

The ratio of data read divided by data written on an individual disk since the last reboot.

Min	Max	Units	Metric Type	Data Type
0	inf	null	derived	numeric

disk.readWriteRatioAverage

The average ratio of data read divided by data written across all disks since the last reboot.

Min	Max	Units	Metric Type	Data Type
0	inf	null	derived	numeric

Notes

Disk Types

• dm-<disk_number>
  • Logical drives mapped by the Linux kernel's logical volume manager (LVM).
• loop<disk_number>
  • Loop devices used to mount filesystems not associated with block devices.
• md<disk_number>
  • Metadisk (RAID) devices. The metadisk driver is used to span a filesystem across multiple physical disks.
• ram<disk_number>
  • RAM disks.
  • The Linux kernel allows for a maximum of 250 RAM disks.
• sd<disk_letter>
  • Small computer system interface (SCSI) disk devices.
  • The Linux kernel allows disk letters ranging from a to p (a maximum of 16 devices), where each device can have a maximum of 15 partitions.
• sd<disk_letter><partition_number>
  • Partitions on the SCSI device.
  • The Linux kernel allows each device to have a maximum of 15 partitions.

Contributing

To contribute to this documentation, see the contributing guide. Any updates to the documentation should be tagged.

$ git tag -a <major.minor.patch> -m "[UPDATE] version."
$ git push origin <major.minor.patch>

Use semantic versioning (semvar) for communicating versions.

• Any new metrics should be communicated as minor updates.
• Any corrections/value modifications should be patches.
• Any documentation restructuring (changing field names, removing fields, etc) should be communicated as a major update.

Usage

The documentation is stored as JSON, a lightweight data-interchange format. Many languages provide JSON support: JavaScript, Python, Go, PHP, Java, Haskell, and others.

You are free to use the JSON documentation, as is. Simply copy the file and use accordingly.

For those using package managers to manage dependencies, we provide package manager support, as outlined below.

Bower

The documentation is registered as a Bower package. Bower provides a straightforward means for managing dependencies.

In order to use Bower, you must first install Node.js and Git. Once the prerequisites are installed,

$ npm install -g bower

To install the latest documentation,

$ bower install doc-metrix-disk

Bower will place the documentation in a bower_components/ directory within the current working directory.

To update to the latest documentation,

$ bower update doc-metrix-disk

Utilities

List of utilities using this documentation:

• Node.js Module

---

License

MIT license.

---

Copyright

Copyright © 2014. NodePrime.