1. Raspberry Pi 2 B Cluster

1.1. Parts

Item	Description	Dimensions (mm)	Unit Power (W)		Unit Price (￥)	Units	Price (￥)	Power (W)	Link
Raspberry Pi 2 Model B	单板机 Single Board Computer	85 x 56 x 17	3.0	MyCase	258.00	10	2,580.00	36.0	http://cn.element14.com/raspberry-pi-accessories?ICID=ap-rpi-2-hwb
NETGEAR GS308	8 口千兆交换机 1Gbps Network Switch	158 x 102 x 26	3.8	Max	299.00	2	598.00	7.6	http://item.jd.com/672092.html
ORICO DCP-4S-BK	4 口 USB 充电器 5V2.4Ax4 USB-charger	96 x 57 x 21			79.00	3	237.00		http://item.jd.com/1208500.html
SAMZHE SZ-601BE	CAT.6E 网线 Network Cable	1000			7.90	12	98.80		http://item.jd.com/636308.html
SAMZHE BL-SZ03	AM/Micro USB 数据线 USB-cable	300			5.9	12	70.80		http://item.jd.com/922605.html
SanDisk 16G Class 10	Micro SD Card				42.90	10	429.00		http://item.jd.com/679772.html
e代家园 GRS11-35	配线箱 Case	350 x 300 x 120			142.00	1	142.00		http://detail.tmall.com/item.htm?id=40266420582
e代家园 GDC-P01	电源模块插座 Power Supply	165 x 49 x 36	40.0	Output	99.00	1	99.00	40.0	http://detail.tmall.com/item.htm?id=42224837564
MIG SL-303CB	电源转换插座 Power Outlet	54 x 40 x 33			19.90	1	19.90		http://item.jd.com/899125.html
单通铜螺柱 M2.5*20+6					0.36	36	12.96		http://detail.tmall.com/item.htm?id=26930900577
单通铜螺柱 M2.5*5+5					0.18	12	2.16		http://detail.tmall.com/item.htm?id=26930900577
双通铜螺柱 M2.5*20					0.28	12	3.36		http://detail.tmall.com/item.htm?id=19636777951
GT-140M	尼龙扎带（x1000）	140 x 2.5			30.00	1	30.00		http://detail.tmall.com/item.htm?id=36844630222
							4,914.48

Q: Why 2 x 8-port 1Gbits network switches?

A: 12 Pis use 12 ports. 2 switches will be connected together, thus use one port for each. We’ll leave 2 ports for external working network. 12 + 1x2 + 2 = 16

Q: Why choose this 4 port USB power charger?

A: The dimentions are perfect for 4 Pis, and the power input connector is standand 5V2.4A 5.5*2.5mm, which is just suitable for GDC-P01 power supply.

Q: How to connect 4 Pis together?

A: At the bottom, use 4 x M2.5*5 + 5 bolts; And 4 x M2.5*20 + 5 between two Pis; At the top, use 4 x M2.5*20. The total heigh is 90mm, when it stands on network switch (26mm heigt), it’s 116mm height, just suitable for the case’s height(120mm).

Q: Is the width of this case enough for 3 groups Pis?

A: Almost. Where you have to lower about 20mm the USB charger for the right group. Furtnately, when 2 network switches are placed one by one at the bottom, there is enough space left on the right side for the lowered USB charger.

Q: Is there still space for USB hard driver?

A: On the top-left side of the case, there is still space for about 4+ USB hard drivers, but you should choose the one that is about 110mm length, and put it vertically, Another choose is use 1.8” hard driver, just like me.

1.2. Installation - Hardware

Parts:

Bundled 4 x Raspberry Pis and 1 x USB Charger together as one group: height 90mm

The layout: 3 x groups stand on 2 x 8-port network switches

The case with PSU installed

Finished:

Lighting:

Lighting:

1.3. Installation - Software

1. check SD card device name:

$ df ­h
/dev/mmcblk0p1  7.5G  2.8G  4.8G  37% /run/media/dcaoyuan/....

2. umount SD card

$ umount /dev/mmcblk0p1

3. dd image

$ sudo dd bs=4M if=~/2015-01-31-raspbian.img of=/dev/mmcblk0
$ sudo sync

4. resizing partitions

$ ssh pi@192.168.2.201
password: raspberry
$ sudo raspi-config
  selecting menu item:
  EXPAND­ ROOTFS ­ Expand Root Partition to Fill SD Card
  reboot

5. ssh login no password

$ ssh pi@pi01 mkdir -p .ssh
pi@pi01's password:

$ cat ~/.ssh/id_rsa.pub | ssh pi@pi01 'cat >> .ssh/authorized_keys'
pi@pi01's password:

$ ssh pi@pi01

6. Extending the life of the SD card

$ vi /etc/fstab

tmpfs /tmp              tmpfs defaults,noatime,nosuid,size=100m                 0 0
tmpfs /var/tmp          tmpfs defaults,noatime,nosuid,size=30m                  0 0
tmpfs /var/log          tmpfs defaults,noatime,nosuid,mode=0755,size=100m       0 0
tmpfs /var/run          tmpfs defaults,noatime,nosuid,mode=0755,size=2m         0 0
tmpfs /var/spool/mqueue tmpfs defaults,noatime,nosuid,mode=0700,gid=12,size=30m 0 0

7. Attach external USB hard drive

# All that max_usb_current=1 does is to set GPIO38 input high, which in turn turns on a
# FET, which connects a second 39K resistor in parallel to an existing one, on pin 5 of
# U13, the AP2553W6 USB power manager, lifting the current limit from 0.6A to double
# that (1.2A)

$ sudo vi /boot/config.txt
# Added line:
max_usb_current=1

$ sudo reboot

# Verify gpio38 value (should be set to high, ie. 1)
$ ls /sys/class/gpio
export gpiochip0  unexport
$ echo 38 > /sys/class/gpio/export
$ cat /sys/class/gpio/gpio38/value
1

8. Mount external hard drive

$ sudo blkid
/dev/mmcblk0p1: SEC_TYPE="msdos" LABEL="boot" UUID="CB99-4C7E" TYPE="vfat"
/dev/mmcblk0p2: UUID="1263ae8d-aaf3-41b6-9ac0-03e7fecb5d6a" TYPE="ext4"
/dev/sda5: LABEL="NEWSMY" UUID="9A60889860887CAF" TYPE="ntfs"

$ sudo mkfs.vfat -n 'usbdisk' -I /dev/sda5
$ sudo blkid
/dev/mmcblk0p1: SEC_TYPE="msdos" LABEL="boot" UUID="CB99-4C7E" TYPE="vfat"
/dev/mmcblk0p2: UUID="1263ae8d-aaf3-41b6-9ac0-03e7fecb5d6a" TYPE="ext4"
/dev/sda5: LABEL="usbdisk" UUID="61A7-F4D8" TYPE="vfat"

$ sudo mkdir /media/usbhdd
$ sudo mount -t vfat -o uid=pi,gid=pi /dev/sdb5 /media/usbhdd

$ sudo vi /etc/fstab # add
UUID="61A7-F4D8" /media/usbhdd   vfat    defaults,uid=pi,gid=pi                 0 0

$ sudo reboot
$ df -h

9. Change hostname

$ sudo hostname pi01

$ sudo vi /etc/hostname # change to
pi01

$ sudo vi /etc/hosts # add line
127.0.0.1 pi01

$ sudo /etc/init.d/hostname.sh start

$ exit
$ ssh pi@pi01
$ echo $HOSTNAME
pi01