col_stats.js

PRIMARY> db.dsl.stats();
{
	"ns" : "sel.dsl",
	"count" : 1044631,
	"size" : 10300275040,
	"avgObjSize" : 9860.20426351506,
	"storageSize" : 10732134320,
	"numExtents" : 5,
	"nindexes" : 2,
	"lastExtentSize" : 2146426864,
	"paddingFactor" : 1.5399999986061403,
	"flags" : 1,
	"totalIndexSize" : 73715072,
	"indexSizes" : {
		"_id_" : 31543264,
		"name_1" : 42171808
	},
	"ok" : 1
}
PRIMARY> db.dsl.findOne()
{
	"_id" : ObjectId("4e1ac7b079f9089b6c378a0a"),
	"name" : "String",
	"vals" : [
		"String"
	]
}
PRIMARY> db.dsl.getIndexes()
[
	{
		"v" : 1,
		"key" : { "_id" : 1 },
		"ns" : "sel.dsl",
		"name" : "_id_"
	},
	{
		"v" : 1,
		"key" : { "name" : 1 },
		"ns" : "sel.dsl",
		"name" : "name_1"
	}
]

iostat_xm5

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.10    0.00    0.06    6.91    0.00   92.92

Device:         rrqm/s   wrqm/s   r/s   w/s    rMB/s    wMB/s avgrq-sz avgqu-sz   await  svctm  %util
sda               0.00   698.80 15.60 267.20     0.40     3.87    30.91    78.75  284.23   3.54 100.02
sda1              0.00     0.00  0.00  0.00     0.00     0.00     0.00     0.00    0.00   0.00   0.00
sda2              0.00     0.00  0.00  0.00     0.00     0.00     0.00     0.00    0.00   0.00   0.00
sda3              0.00     0.00  0.00  0.00     0.00     0.00     0.00     0.00    0.00   0.00   0.00
sda4              0.00     0.00  0.00  0.00     0.00     0.00     0.00     0.00    0.00   0.00   0.00
sda5              0.00   698.80 15.60 267.20     0.40     3.87    30.91    78.75  284.23   3.54 100.02
dm-0              0.00     0.00 15.40 961.00     0.41     3.83     8.88   330.21  340.91   1.02 100.02
dm-1              0.00     0.00  0.00  0.00     0.00     0.00     0.00     0.00    0.00   0.00   0.00

update.rb

# upsert
@mongo.update({:name => key}, {'$push' => { 'vals' => value}}, :upsert => true)
# pop oldest if vals.size > 50
@mongo.update({:name => key, :vals => {'$size' => 51} }, {'$pop' => { 'vals' => -1 }})