Class: ServerMetrics::Disk

Inherits:
MultiCollector show all
Defined in:
lib/server_metrics/collectors/disk.rb

Overview

Collects Disk metrics on eligible filesystems. Reports a hash of hashes, with the first hash keyed by device name.

TODO: Currently, this reports on devices that begins with /dev as listed by ‘mount`. Revisit this. TODO: relies on /proc/diskstats, so not mac compatible. Figure out mac compatibility

Instance Attribute Summary

Attributes inherited from Collector

#collector_id, #data, #error

Instance Method Summary collapse

Methods inherited from MultiCollector

#counter, #memory, #remember, #report

Methods inherited from Collector

#convert_to_mb, #counter, from_hash, #initialize, #linux?, #memory, #option, #osx?, #remember, #report, #run, #to_hash

Constructor Details

This class inherits a constructor from ServerMetrics::Collector

Instance Method Details

#build_report ⇒ Object 



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# File 'lib/server_metrics/collectors/disk.rb', line 8

def build_report
  ENV['LANG'] = 'C' # forcing English for parsing
  @df_output = `df -Pkh`.split("\n")
  @devices = `mount`.split("\n").grep(/^\/dev/).map{|l|l.split.first} # any device that starts with /dev
  @disk_stats = `cat /proc/diskstats`.split("\n")

  @devices.each do |device|
    get_sizes(device) # does its own reporting
    get_stats(device) if linux? # does its own reporting
  end
end

#get_sizes(device) ⇒ Object

called from build_report for each device



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# File 'lib/server_metrics/collectors/disk.rb', line 21

def get_sizes(device)
  header_line=@df_output.first
  headers = header_line.split(/\s+/,6) # limit to 6 columns - last column is "mounted on"
  parsed_lines=[] # Each line will look like {"%iused" => "38%","Avail" => "289Gi", "Capacity=> "38%", "Filesystem"=> "/dev/disk0s2","Mounted => "/", "Size" => "465Gi", "Used" => "176Gi", "ifree" => "75812051", "iused"  => "46116178"}

  @df_output[1..@df_output.size-1].each do |line|
    values=line.split(/\s+/,6)
    parsed_lines<<Hash[headers.zip(values)]
  end

  # select the right line
  hash = parsed_lines.select{|l| l["Filesystem"] == device}.first
  result = {}
  hash.each_pair do |key,value|
    key=normalize_key(key) # downcase, make a symbol, etc
    value = convert_to_mb(value) if [:avail, :capacity, :size, :used].include?(key)
    result[key]=value
  end

  report(device, result)
end

#get_stats(device) ⇒ Object

called from build_report for each device



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# File 'lib/server_metrics/collectors/disk.rb', line 44

def get_stats(device)
  stats = iostat(device)

  if stats
    counter(device, :rps,   stats['rio'],        :per => :second)
    counter(device, :wps,   stats['wio'],        :per => :second)
    counter(device, :rps_kb, stats['rsect'] / 2,  :per => :second)
    counter(device, :wps_kb, stats['wsect'] / 2,  :per => :second)
    counter(device, :utilization,  stats['use'] / 10.0, :per => :second)
    # Not 100% sure that average queue length is present on all distros.
    if stats['aveq']
      counter(device, :average_queue_length,  stats['aveq'], :per => :second)
    end

    if old = memory(device, "stats")
      ios = (stats['rio'] - old['rio']) + (stats['wio']  - old['wio'])

      if ios > 0
        await = ((stats['ruse'] - old['ruse']) + (stats['wuse'] - old['wuse'])) / ios.to_f

        report(device, :await => await)
      end
    end

    remember(device, "stats" => stats)
  end
end