disk-stat

  ______   ___ _______ ___ ___  _______ _______ _______ _______
 |   _  \ |   |   _   |   Y   )|   _   |       |   _   |       |
 |.  |   \|.  |   1___|.  1  / |   1___|.|   | |.  1   |.|   | |
 |.  |    |.  |____   |.  _  \ |____   `-|.  |-|.  _   `-|.  |-'
 |:  1    |:  |:  1   |:  |   \|:  1   | |:  | |:  |   | |:  |
 |::.. . /|::.|::.. . |::.| .  |::.. . | |::.| |::.|:. | |::.|
 `------' `---`-------`--- ---'`-------' `---' `--- ---' `---'

Note: This repo can be found on npm here: disk-stat

Note: This repo can be found on github here: node-disk-stat

Caveat: Works by parsing /proc/diskstats, so will only work on nix OS.

Note: If you are interested in the amount of disk space used/free/etc check out diskusage

Install

npm install disk-stat

Examples

Require the module:

var diskStat = require('disk-stat');

By default usageRead() returns usage per second in bytes on device sda:

diskStat.usageRead(function(bytesPerSecond) {
  console.log(bytesPerSecond);
});

Specify some opts for usageRead() to customize return value, see docs below for more options:

diskStat.usageRead({
    device: 'sda1',
    units: 'MiB',
  },
  function(mbPerSecond) {
    console.log(mbPerSecond);
});

Get all fields available from /proc/diskstats formatted as an object:

var raw = diskStat.raw();
console.log(raw);

usageRead([opts,] cb)

Async function which returns data, the disk usage for reads per second in opts.units on opts.device over opts.sampleMs assuming a sector size in bytes of sectorSizeBytes

Option	Type	Default	Explanation
opts	Object	see below	Options object, specify what you need, the defaults will be filled in
opts.units	String	'bytes'	The units of the returned value, can be one of bytes, KiB, MiB or GiB
opts.sectorSizeBytes	Number	512	The number of bytes in each sector on the device
opts.device	String	'sda'	device is the device name to measure, see raw() for a list of device names
opts.sampleMs	String	1000	sampleMs is the amount of time to take the measurement over
cb	Function	none	Callback which has signature cb(usagePerSecond)

Note: get system sector size in bytes: sudo hdparm -I /dev/sda | grep Physical

Note: get system sector size in bytes: cat /sys/block/sda/queue/physical_block_size

usageWrite([opts,] cb)

Async function which returns data, the disk usage for writes per second in opts.units on opts.device over opts.sampleMs assuming a sector size in bytes of sectorSizeBytes

Option	Type	Default	Explanation
opts	Object	see below	Options object, specify what you need, the defaults will be filled in
opts.units	String	'bytes'	The units of the returned value, can be one of bytes, KiB, MiB or GiB
opts.sectorSizeBytes	Number	512	The number of bytes in each sector on the device
opts.device	String	'sda'	device is the device name to measure, see raw() for a list of device names
opts.sampleMs	String	1000	sampleMs is the amount of time to take the measurement over
cb	Function	none	Callback which has signature cb(usagePerSecond)

Note: get system sector size: sudo hdparm -I /dev/sda | grep Physical

Note: get system sector size: cat /sys/block/sda/queue/physical_block_size

raw()

Returns an object representing the data in /proc/diskstats.

{
  ram0:
   { deviceNumber: '1',
     deviceNumberMinor: '0',
     readsCompleted: '0',
     readsMerged: '0',
     sectorsRead: '0',
     msReading: '0',
     writesCompleted: '0',
     writesMerged: '0',
     sectorsWritten: '0',
     msWriting: '0',
     iosPending: '0',
     msIo: '0',
     msWeightedIo: '0' },

  ...

  loop0:
   { deviceNumber: '7',
     deviceNumberMinor: '0',
     readsCompleted: '0',
     readsMerged: '0',
     sectorsRead: '0',
     msReading: '0',
     writesCompleted: '0',
     writesMerged: '0',
     sectorsWritten: '0',
     msWriting: '0',
     iosPending: '0',
     msIo: '0',
     msWeightedIo: '0' },

  ...

  sda:
   { deviceNumber: '8',
     deviceNumberMinor: '0',
     readsCompleted: '163027',
     readsMerged: '15815',
     sectorsRead: '12564320',
     msReading: '1662800',
     writesCompleted: '421527',
     writesMerged: '525281',
     sectorsWritten: '27001720',
     msWriting: '8517992',
     iosPending: '0',
     msIo: '1962780',
     msWeightedIo: '10180908' },
  sda1:
   { deviceNumber: '8',
     deviceNumberMinor: '1',
     readsCompleted: '114879',
     readsMerged: '15186',
     sectorsRead: '4628658',
     msReading: '1397120',
     writesCompleted: '390778',
     writesMerged: '483151',
     sectorsWritten: '25718648',
     msWriting: '8096212',
     iosPending: '0',
     msIo: '1755812',
     msWeightedIo: '9493500' },
  sda2:
   { deviceNumber: '8',
     deviceNumberMinor: '2',
     readsCompleted: '2',
     readsMerged: '0',
     sectorsRead: '4',
     msReading: '36',
     writesCompleted: '0',
     writesMerged: '0',
     sectorsWritten: '0',
     msWriting: '0',
     iosPending: '0',
     msIo: '36',
     msWeightedIo: '36' },
  sda5:
   { deviceNumber: '8',
     deviceNumberMinor: '5',
     readsCompleted: '237',
     readsMerged: '193',
     sectorsRead: '3440',
     msReading: '736',
     writesCompleted: '1329',
     writesMerged: '4130',
     sectorsWritten: '43680',
     msWriting: '9672',
     iosPending: '0',
     msIo: '2704',
     msWeightedIo: '10408' },
  sda6:
   { deviceNumber: '8',
     deviceNumberMinor: '6',
     readsCompleted: '47728',
     readsMerged: '436',
     sectorsRead: '7930770',
     msReading: '264080',
     writesCompleted: '22937',
     writesMerged: '38000',
     sectorsWritten: '1239392',
     msWriting: '392228',
     iosPending: '0',
     msIo: '266864',
     msWeightedIo: '656260' }
}

  /proc/diskstats

  https://www.kernel.org/doc/Documentation/iostats.txt

  Each set of stats only applies to the indicated device; if you want
  system-wide stats you'll have to find all the devices and sum them all up.

  Field  1 -- # of reads completed
      This is the total number of reads completed successfully.
  Field  2 -- # of reads merged, field 6 -- # of writes merged
      Reads and writes which are adjacent to each other may be merged for
      efficiency.  Thus two 4K reads may become one 8K read before it is
      ultimately handed to the disk, and so it will be counted (and queued)
      as only one I/O.  This field lets you know how often this was done.
  Field  3 -- # of sectors read
      This is the total number of sectors read successfully.
  Field  4 -- # of milliseconds spent reading
      This is the total number of milliseconds spent by all reads (as
      measured from __make_request() to end_that_request_last()).
  Field  5 -- # of writes completed
      This is the total number of writes completed successfully.
  Field  6 -- # of writes merged
      See the description of field 2.
  Field  7 -- # of sectors written
      This is the total number of sectors written successfully.
  Field  8 -- # of milliseconds spent writing
      This is the total number of milliseconds spent by all writes (as
      measured from __make_request() to end_that_request_last()).
  Field  9 -- # of I/Os currently in progress
      The only field that should go to zero. Incremented as requests are
      given to appropriate struct request_queue and decremented as they finish.
  Field 10 -- # of milliseconds spent doing I/Os
      This field increases so long as field 9 is nonzero.
  Field 11 -- weighted # of milliseconds spent doing I/Os
      This field is incremented at each I/O start, I/O completion, I/O
      merge, or read of these stats by the number of I/Os in progress
      (field 9) times the number of milliseconds spent doing I/O since the
      last update of this field.  This can provide an easy measure of both
      I/O completion time and the backlog that may be accumulating.

Contributing

Just send a PR, or create an issue if you are not sure.

Areas ripe for contribution:

• testing
• cross compatability for windoze and darwin/osx
• performance
• bugs

Other Stat Modules

• cpu-stat npm git
• net-stat npm git
• disk-stat npm git
• mem-stat npm git

Note: net-stat, disk-stat, mem-stat only work on nix platforms.

License

MIT