我使用macports安装了MongoDB，并try 运行mongo命令来启动mongo shell.我收到了以下错误:
warning: Failed to connect to 127.0.0.1:27017, reason: errno:61 Connection refused
Error: couldn't connect to server 127.0.0.1:27017 (127.0.0.1), connection attempt failed
at src/mongo/shell/mongo.js:146
然后我运行了mongod次，收到了以下错误:
$ [initandlisten] MongoDB starting : pid=11984 port=27017 dbpath=/data/db 64-bit host=Nikitas-MacBook-Air.local
$ [initandlisten]
$ [initandlisten] ** WARNING: soft rlimits too low. Number of files is 256, should be at least 1000
$ [initandlisten] db version v2.6.0
$ [initandlisten] git version: nogitversion
$ [initandlisten] build info: Darwin tennine-slave.macports.org 13.1.0 Darwin Kernel Version
13.1.0: Thu Jan 16 19:40:37 PST 2014; root:xnu-2422.90.20~2/RELEASE_X86_64 x86_64 BOOST_LIB_VERSION=1_55
$ [initandlisten] allocator: tcmalloc
$ [initandlisten] options: {}
$ [initandlisten] exception in initAndListen: 10296
*********************************************************************
ERROR: dbpath (/data/db) does not exist.
Create this directory or give existing directory in --dbpath.
See http://dochub.mongodb.org/core/startingandstoppingmongo
*********************************************************************
, terminating
$ [initandlisten] dbexit:
$ [initandlisten] shutdown: going to close listening sockets...
$ [initandlisten] shutdown: going to flush diaglog...
$ [initandlisten] shutdown: going to close sockets...
$ [initandlisten] shutdown: waiting for fs preallocator...
$ [initandlisten] shutdown: lock for final commit...
$ [initandlisten] shutdown: final commit...
$ [initandlisten] shutdown: closing all files...
$ [initandlisten] closeAllFiles() finished
$ [initandlisten] dbexit: really exiting now
我在哪里创建/data/db目录，根目录？当我运行mongo时，第二个错误是errno:61的原因吗？