ajayverghese · February 14, 2013 18:50 · Feb 14, 2013
diff --git a/graphite-diskusage.py b/graphite-diskusage.py
@@ -0,0 +1,63 @@
+#!/usr/bin/python
+
+'''
+Calculate disk space required for given graphite retention policy and number of
+metrics
+'''
+
+#######################################
+
+# retention policy
+retentions = '10s:6h,1m:7d,10m:2y'
+
+# number of metrics to be stored
+num_metrics = 3000
+
+#######################################
+
+# time translations
+second = 1
+minute = 60 * second
+hour = 60 * minute
+day = 24 * hour
+week = 7 * day
+month = 30 * day
+year = 52 * week
+time_map = {
+   's': second,
+   'h': hour,
+   'd': day,
+   'w': week,
+   'm': minute,
+   'y': year
+}
+
+datapoint_size = 12 # 12 bytes per datapoint
+
+def get_num_datapoints(retention):
+   '''
+   calculate number of datapoints based on the given retention policy string
+   '''
+   total_datapoints = 0
+   for policy in retentions.split(','):
+      resolution, period = policy.split(':')
+      resolution_num, resolution_type = resolution[:-1], resolution[-1]
+      period_num, period_type = period[:-1], period[-1]
+      resolution_points = int(resolution_num) * time_map[resolution_type]
+      period_points = int(period_num) * time_map[period_type]
+      points = period_points / resolution_points
+      print '%s for %s => %s data points' % (resolution, period, points)
+      total_datapoints += points
+   return total_datapoints
+
+datapoints = get_num_datapoints(retentions)
+disk_required_per_metric = (datapoints * datapoint_size * 1.0) / (1024 * 1024)
+total_disk_required = disk_required_per_metric * num_metrics
+
+print '=' * 30
+print 'Number of metrics: %s' % num_metrics
+print 'Retention policy: %s' % retentions
+print 'Num datapoints per metric: %s' % datapoints
+print 'Disk space per metric: %s MB' % disk_required_per_metric
+print 'Total disk space for %s metrics: %s MB' % (num_metrics, total_disk_required)
+print '=' * 30