thin_metadata_size: new metadata size calculation tool

thin-provisioning/thin_metadata_size

@@ -0,0 +1,121 @@
+#!/usr/bin/env ruby
+#
+# Copyright (C) 2013 Red Hat, GmbH
+# 
+# This file is released under the GPL
+#
+#
+# Script to calculate device-mapper thin privisioning
+# metadata device size based on pool, block size and
+# maximum expected thin provisioned devices.
+#
+
+require 'optparse'
+require 'pathname'
+
+#----------------------------------------------------------------
+
+$prg = Pathname.new($0).basename
+$btree_entrysize = 16
+$btree_nodesize = 4096
+
+def init_units
+  units = Hash.new
+  units[:chars] = "sKkMmGgTtPpEeZzYy"
+  units[:strings] = [ 'sectors',
+                      'kilobytes', 'kibibytes', 'megabytes',  'mebibytes',
+                      'gigabytes', 'gibibytes', 'terabytes',  'tebibytes',
+                      'petabytes', 'pebibytes', 'exabytes',   'ebibytes',
+                      'zetabytes', 'zebibytes', 'yottabytes', 'yobibytes' ]
+  units[:factors] =  Array.new
+
+  units[:factors][0] = 512
+  1.step(8) do |e|
+    units[:factors][(e - 1) * 2 + 1] = 1024**e
+    units[:factors][(e - 1) * 2 + 2] = 1000**e
+  end
+  units
+end
+
+def check_opts(opts)
+  abort "#{$prg} - 3 arguments required!" if opts.length < 3
+  abort "#{$prg} - poolsize must be much larger than blocksize" if opts[:poolsize] < opts[:blocksize] * 16
+  abort "#{$prg} - maximum number of thin provisioned devices must be > 0" if opts[:maxthins].nil? || opts[:maxthins] == 0
+end
+
+def to_sectors(size, units)
+  unit_chars = units[:chars]
+
+  a = size.split(/[#{unit_chars}]/)
+  s = size.to_i.to_s
+  abort "#{$prg} - only one unit character allowed!" if a.length > 1 || size.length - s.length > 1
+  abort "#{$prg} - invalid unit specifier!" if s != a[0]
+  idx = unit_chars.index(size[a[0].length])
+  r = size.to_i * units[:factors][idx] / 512
+  r
+end
+
+def parse_command_line(argv, units)
+  opts = {}
+  unit_chars = units[:chars]
+
+  os = OptionParser.new do |o|
+    o.banner = "Thin Provisioning Metadata Size Calculator.\nUsage: #{$prg} [opts]"
+    o.on('-b', '--blocksize BLOCKSIZE', String,
+         "Block size, ie. allocation unit size for thin provisioned devices.") do |bs|
+      opts[:blocksize] = to_sectors(bs, units)
+    end
+    o.on('-s', '--poolsize SIZE', String, "Size of the pool device.") do |ps|
+      opts[:poolsize] = to_sectors(ps, units)
+    end
+    o.on('-m', '--maxthins MAXTHINS', Integer, "Size of the pool device.") do |mt|
+      opts[:maxthins] = mt
+    end
+    o.on('-u', '--units [skKmMgGtTpP]', String, "Output unit specifier.") do |u|
+      if u =~ /[#{unit_chars}]/
+        opts[:units] = u
+      else
+        abort "#{$prg} - output unit specifier invalid."
+      end
+    end
+    o.on('-n', '--numeric-only', "Output numeric value only.") do
+      opts[:numeric] = true || nil
+    end
+    o.on('-h', '--help', "Outout this help.") do
+      puts o
+      exit
+    end
+  end
+
+  begin
+    os.parse(argv)
+  rescue OptionParser::ParseError => e
+    abort "#{$prg} #{e}\n#{$prg} #{os}"
+  end
+
+  check_opts(opts)
+  opts
+end
+
+def entries_per_node
+  btree_node_headersize = 64
+  ($btree_nodesize - btree_node_headersize) / $btree_entrysize
+end
+
+def estimated_result(opts, units)
+  idx = opts[:units] ? units[:chars].index(opts[:units]) : 0
+  r = 1.0 + ((opts[:poolsize] / opts[:blocksize] / entries_per_node) + opts[:maxthins]) * 512 / 8
+  r /= units[:factors][idx]
+  tmp = "%.2f" % r
+  # FIXME: avoid zero decimal places
+  r = tmp.to_f > 0.0 ? tmp : "%.4e" % r
+  r = "#{$prg} estimated metadata area size is #{r} #{units[:strings][idx]}." if !opts[:numeric]
+  r
+end
+
+
+#----------------------------------------------------------------
+# Main
+
+units = init_units
+puts estimated_result(parse_command_line(ARGV, units), units)