2.Mongostat mongostat n n:刷新秒数 反应当前mongod的负荷
http://docs.mongodb.org/manual/reference/program/mongostat/
inserts - # of inserts per second (* means replicated op)
query - # of queries per second
update - # of updates per second
delete - # of deletes per second
getmore - # of get mores (cursor batch) per second
command - # of commands per second, on a slave its local|replicated
flushes - # of fsync flushes per second
mapped - amount of data mmaped (total data size) megabytes
vsize - virtual size of process in megabytes
res - resident size of process in megabytes
faults - # of pages faults per sec
locked - name of and percent time for most locked database
idx miss - percent of btree page misses (sampled)
qr|qw - queue lengths for clients waiting (read|write)
ar|aw - active clients (read|write)
netIn - network traffic in - bits
netOut - network traffic out - bits
conn - number of open connections
set - replica set name
repl - replication type
PRI - primary (master)
SEC - secondary
REC - recovering
UNK - unknown
SLV - slave
RTR - mongos process ("router")