Upgrade MongoDB v2.4.9 => 2.6.6 ref: http://qiita.com/mknkisk/items/ee826d485430e018cd3c

file0.txt

pacman -Syu

file1.txt

vim /usr/lib/systemd/system/mongodb.service

[Unit]
Description=High-performance, schema-free document-oriented database
After=network.target

[Service]
User=mongodb
ExecStart=/usr/bin/mongod --quiet --config /etc/mongodb.conf
# Add this line
LimitNOFILE=64000

[Install]
WantedBy=multi-user.target

file2.txt

mongo admin
> db.auth('user', 'pass')
> 
> // slaveOkにしないとcheckできない！
> db.getMongo().setSlaveOk()
> db.upgradeCheckAllDBs()
...
true # true を確認する

file3.txt

mongo
> rs.stepDown();

file4.txt

systemctl daemon-reload

file5.txt

systemctl restart mongodb

file6.txt

db admin
db.auth('user', 'pass')
db.getSiblingDB("admin").runCommand({authSchemaUpgrade: 1 });