A few weeks ago I received my first Intel Edison in the mail. After a bit of tinkering I was able to bootstrap a small Cassandra cluster on this little SoC. I tweeted a picture showing it up and running with OpsCenter connected in the background.
— Christopher Bradford (@bradfordcp) February 15, 2015
I will ouline how to bootstrap the Intel Edison and install a functioning Cassandra cluster. Note that even though you can run Cassandra on the Edison, that doesn’t necessarily mean you should.
What is an Intel Edison?
The Intel Edison is a development platform for embedded applications boasting impressive specs:
- Dual core Intel Atom SoC (500MHz)
- 1GB LPDDR3 RAM
- 802.11 a/b/g/n Wifi
- Bluetooth 4.0 LE
In this project we’re going to need to provide power, serial console access, and some additional storage capacity. These features can be stacked on to the Edison through blocks. If you’re framiliar with Arduino shields, the concept is the same.
- Intel Edison
- SparkFun Block for Intel® Edison – Console
- SparkFun Block for Intel® Edison – microSD
- Intel Edison Hardware Pack
- SanDisk Ultra 32GB UHI-I/Class 10 Micro SDHC Memory Card
At the time of publication a single node in our cluster costs approximately $119 USD.
After all of the components have arrived it is time to start assembling the node. Each node is comprised of 3 layers (Edison => Console Block => MicroSD Block) which are connected via 70-pin connectors on the top and bottom of the blocks. The order of the Console and MicroSD blocks are not important, but the Edison must be placed on the top. In our assembly we have placed the MicroSD block on the bottom as fewer components are exposed in this configuration.
- Begin assembly by attaching two standoffs from the hardware pack onto the top of the console board with the small phillips head bolts. This will expose two posts that will support the Edison.
- Attach 4 standoffs to the bottom of the board with nuts
- Connect the Edison to the Console block and affix it to the standoffs with two nuts.
- Next add the MicroSD block securing it with 4 additional standoffs.
Bootstrap the Edison
With the node assembled it is time to start setting up the software side. Intel provides a step by step getting started guide. For our setup we should configure the password and connect the device to our wifi network.
Connect to the Edison via the USB serial device. Note that on your device the value A402YSYU may be different
screen /dev/tty.usbserial-A402YSYU 115200 –L
- Press enter twice and a login prompt should appear
rootand press enter
- Run the
configure_edisonprogram. This will prompt you for a name for the device, a new root password and walkthrough the wifi setup process.
Prepare the MicroSD card. We first unmount the card (which is auto-mounted at
/media/sdcard). Next we run fdisk and repartition the card. Finally we create the filesystem.
umount /media/sdcard fdisk /dev/mmcblk1 d # Delete the current partition (There is usually only 1 if any) n # Create a new partition p # Mark the partition as primary 1 # Assign it the number 1
# Select the first block on the device # Select the last block on the device w # Write the change to the disk and exit mkfs.ext4 /dev/mmcblk1p1
Setup the Cassandra data directory
mount /dev/mmcblk1p1 /media/sdcard mkdir /media/sdcard/cassandra
exitand press enter. Future setup will be performed over SSH.
Cassandra is written in java and requires the JRE to run. It is recommended that we use Oracle’s JRE version 7.
- Download the
jre-7u75-linux-i586.tar.gzfrom the Oracle download page. This requires accepting a license agreement before downloading the file.
- Copy the file to the Edison via SFTP
Extract the file
tar xvzpf jre-7u75-linux-i586.tar.gz
Set the JAVA_HOME environment variable to point at the extracted directory
It may be worthwhile to place this in your
.bash_profileto prevent having to run this every time we start Cassandra.
Cassandra’s start script utilizes the getopt command. The Yocto Linux distribution running on the Edison does not ship with this utility. This package may be found through Yocto’s Recipe reporting system. From here there is a link to the source code which we will pull down and compile on the Edison.
Download the util-linux package from kernel.org
Extract the package
tar xvf util-linux-2.25.2.tar.xz
Build the source
cd util-linux ./configure make getopt
Install the built binary
mkdir -p /usr/local/bin cp getopt /usr/local/bin
Install & Configure Apache Cassandra
Download Cassandra 2.1.3
Extract the package
tar xvzpf apache-cassandra-2.1.3-bin.tar.gz
Configure Cassandra – be sure to edit the values listed below instead of replacing the file
cluster_name: "Edison Cluster" listen_address:
rpc_address: seed_provider: - class_name: org.apache.cassandra.locator.SimpleSeedProvider parameters: - seeds: " ip here>" data_file_directories: - /media/sdcard/cassandra/data commitlog_directory: /media/sdcard/cassandra/commitlog saved_caches_directory: /media/sdcard/cassandra/saved_caches
/etc/hosts– The hostname must be in /etc/hosts or DNS
Intel Edison Micro-Cluster Benchmarks
nodetool -h 192.168.1.50 statusDatacenter: datacenter1=======================Status=Up/Down|/ State=Normal/Leaving/Joining/Moving-- Address Load Tokens Owns (effective) Host ID RackUN 192.168.1.50 70.54 KB 256 100.0% 2395b793-2d8b-4c31-931c-64fa94097cc5 rack1
Cassandra Stress Writes
./cassandra-stress write n=100000 -node 192.168.1.50Created keyspaces. Sleeping 1s for propagation.Warming up WRITE with 50000 iterations...INFO 18:36:16 Using data-center name 'datacenter1' for DCAwareRoundRobinPolicy (if this is incorrect, please provide the correct datacenter name with DCAwareRoundRobinPolicy constructor)Connected to cluster: Edison ClusterDatatacenter: datacenter1; Host: /192.168.1.50; Rack: rack1INFO 18:36:16 New Cassandra host /192.168.1.50:9042 addedSleeping 2s...Running WRITE with 200 threads for 100000 iteration...Results:op rate : 1922partition rate : 1922row rate : 1922latency mean : 104.0latency median : 87.9latency 95th percentile : 176.9latency 99th percentile : 381.7latency 99.9th percentile : 696.5latency max : 1855.3total gc count : 4total gc mb : 569total gc time (s) : 2avg gc time(ms) : 474stdev gc time(ms) : 19Total operation time : 00:00:52END
Cassandra Stress Reads
./cassandra-stress read n=100000 -node 192.168.1.50Warming up READ with 50000 iterations...Failed to connect over JMX; not collecting these statsINFO 18:41:53 Using data-center name 'datacenter1' for DCAwareRoundRobinPolicy (if this is incorrect, please provide the correct datacenter name with DCAwareRoundRobinPolicy constructor)Connected to cluster: Edison ClusterINFO 18:41:53 New Cassandra host /192.168.1.50:9042 addedDatatacenter: datacenter1; Host: /192.168.1.50; Rack: rack1Sleeping 2s...... id, total ops , adj row/s, op/s, pk/s, row/s 4 threads, 100000 , 238, 238, 238, 238 8 threads, 100000 , -0, 399, 399, 399 16 threads, 100000 , 588, 588, 588, 588 24 threads, 100000 , 725, 722, 722, 722 36 threads, 100000 , -0, 873, 873, 873 54 threads, 100000 , -0, 1096, 1096, 1096 81 threads, 100000 , -0, 1247, 1247, 1247121 threads, 100000 , -0, 1376, 1376, 1376181 threads, 100000 , -0, 1444, 1444, 1444271 threads, 99688 , -0, 1532, 1532, 1532406 threads, 100000 , -0, 1515, 1515, 1515609 threads, 100000 , -0, 1500, 1500, 1500913 threads, 100000 , 1509, 1501, 1501, 1501END
Overall we’re seeing ~1,900 writes per second and ~1,500 reads per second. That’s respectable for a tiny SoC storing the data on a MicroSD card and communicating over wifi. Bringing up our Access Point’s (AP) interface we can take a look at the wireless performance of our nodes. The node used in these stress tests was connected via 802.11 g/n from approximately 10 feet away from the AP. Looking at the graphs we see the node connected at 75mpbs and some issues with retried frames (both in and out). A second node was brought online which didn’t have these issues. It connected at 150mbps via 802.11 a/n and didn’t have as many retries in either direction.
The Edison is a quite capable SoC. It handled running Cassandra with no problem. The configuration may be futher tuned to match the hardware. Remember even though you can run Cassandra on the Edison, that doesn’t necessarily mean you should. If you’re stuck trying to tune and configure Cassandra, be sure to contact us! Don’t hesitate to get in touch to let us know if you have any thoughts, feedback or criticisms of this article!