Main Advantages of Riak
Riak replicates key/value stores across a cluster of nodes with a default n_val of three. In the case of node outages due to network partition or hardware failures, data can still be written to a neighboring node beyond the initial three, and read-back due to its "masterless" peer-to-peer architecture.
Queries
Riak supports a REST API through HTTP and Protocol Buffers for basic PUT, GET, POST, and DELETE functions. Additional query choices are offered including secondary indices, Riak Search leveraging the Apache Solr Engine with Solr client query APIs and MapReduce. MapReduce has native support for both JavaScript (using the SpiderMonkey runtime) and Erlang.
Predictable Latency
Riak evenly distributes data across nodes with consistent hashing and can provide an excellent latency profile, even in the case of multiple node failures. Key/Values can be stored in memory, disk, or a combination depending on which pluggable backend one chooses.
Multi-Datacenter Replication
In multi-datacenter replication, one cluster acts as a "primary cluster". The primary cluster handles replication requests from one or more "secondary clusters" (generally located in other regions or countries). If the datacenter with the primary cluster goes down, a secondary cluster can take over as the primary cluster.
There are two primary modes of operation: fullsync and realtime. In fullsync mode, a complete synchronization occurs between primary and secondary cluster(s), by default every 360 minutes. In realtime mode, continual, incremental synchronization occurs - replication is triggered by new updates.
Install Riak from Source
Instructions for downloading and installing Riak from source.
Impotent thing is, You must have Xcode tools installed from Apple's Developer website
Riak requires Erlang R15B01. Installation of Erlang R15B01 from source..
First download and unpack the source:
curl -O http://erlang.org/download/otp_src_R15B01.tar.gz
tar zxvf otp_src_R15B01.tar.gz
cd otp_src_R15B01
Then configure Elang using LLVM (the default):
CFLAGS=-O0 ./configure --disable-hipe --enable-smp-support --enable-threads \
--enable-kernel-poll --enable-darwin-64bit
Now build and install, you will prompted for your sudo password.
make && sudo make install
Download and unpack Riak-1.4.8
After installing Erlang, We are going to download and unpack the source distribution of Riak-1.4.8.
wget http://s3.amazonaws.com/downloads.basho.com/riak/1.4/1.4.8/riak-1.4.8.tar.gz
tar zxvf riak-1.4.8.tar.gz
cd riak-1.4.8
make all
Setup and startup Five nodes
After successful built, we are going to setup five self-contained nodes on Riak.
First, make five nodes:
make devrel DEVNODES=5
You have just generated a dev directory. Let's go into that directory to check out its these directories dev1, dev2, dev3, dev4:
cd dev; ls
Each directory starting with dev is a complete, self-contained package containing a Riak node. We need to start all nodes, you can use a for loop to iterate through and start the available nodes::
for node in `ls`; do $node/bin/riak start; done
--ulimit warning--
At this point you may receive a warning message to increase the number of open file handles (ulimit). To check the current limits:
launchctl limit maxfiles
To adjust the maximum open file limits, edit(create) /etc/launchd.conf (using any editor with sudo previllage)and increase the limits for soft and hard as appropriate. add the lines as follows:
limit maxfiles 16384 32768
Save the file, and restart the system for the new limits to take effect. After restarting,
verify current limits:
launchctl limit
cpu unlimited unlimited
filesize unlimited unlimited
data unlimited unlimited
stack 8388608 67104768
core 0 unlimited
rss unlimited unlimited
memlock unlimited unlimited
maxproc 709 1064
maxfiles 16384 32768
After that start the all five nodes again using above for loop command and check running nodes, to do this run :
ps aux | grep beam
This should give you granular details on the five running Riak nodes. If you'd like to simply check which nodes are running and which are not, you can run the riak ping command on for loop:
for node in `ls`; do $node/bin/riak ping; done
If the response is PONG, then the node is up and running. Otherwise, the node is currently stopped
Cluster joining
The next step is to join these five nodes together to form a cluster. You can do this using the Riak Admin tool. Specifically, what we want to do is join dev2,dev3, dev4, and dev5 to dev1: , to do this run:
for n in {2..5}; do dev$n/bin/riak-admin cluster join dev1@127.0.0.1; done
To make the above joins take effect, you first must review the plan:
dev1/bin/riak-admin cluster plan
The plan will print out a synopsis of what it plans to do, and how the cluster will look after this is completed.
=============================== Staged Changes ================================
Action Nodes(s)
-------------------------------------------------------------------------------
join 'dev2@127.0.0.1'
join 'dev3@127.0.0.1'
join 'dev4@127.0.0.1'
join 'dev5@127.0.0.1'
-------------------------------------------------------------------------------
NOTE: Applying these changes will result in 1 cluster transition
###############################################################################
After cluster transition 1/1
###############################################################################
================================= Membership ==================================
Status Ring Pending Node
-------------------------------------------------------------------------------
valid 100.0% 20.3% 'dev1@127.0.0.1'
valid 0.0% 20.3% 'dev2@127.0.0.1'
valid 0.0% 20.3% 'dev3@127.0.0.1'
valid 0.0% 20.3% 'dev4@127.0.0.1'
valid 0.0% 18.8% 'dev5@127.0.0.1'
-------------------------------------------------------------------------------
Valid:5 / Leaving:0 / Exiting:0 / Joining:0 / Down:0
Transfers resulting from cluster changes: 51
12 transfers from 'dev1@127.0.0.1' to 'dev5@127.0.0.1'
13 transfers from 'dev1@127.0.0.1' to 'dev4@127.0.0.1'
13 transfers from 'dev1@127.0.0.1' to 'dev3@127.0.0.1'
13 transfers from 'dev1@127.0.0.1' to 'dev2@127.0.0.1'
Finally, you can commit the batch:
dev2/bin/riak-admin cluster commit
Test the cluster
Now we now a have a running five-node Riak cluster. Let's make sure it's working properly. For this we have a couple of options. A simple option is to run the member-status command on one of our nodes:
dev1/bin/riak-admin member-status
This will give us a high-level view of our cluster and tell us the percentage of the ring that each node manages:
================================= Membership ==================================
Status Ring Pending Node
-------------------------------------------------------------------------------
valid 20.3% -- 'dev1@127.0.0.1'
valid 20.3% -- 'dev2@127.0.0.1'
valid 20.3% -- 'dev3@127.0.0.1'
valid 20.3% -- 'dev4@127.0.0.1'
valid 18.8% -- 'dev5@127.0.0.1'
-------------------------------------------------------------------------------
Valid:5 / Leaving:0 / Exiting:0 / Joining:0 / Down:0
You should now have a five-node Riak cluster up and running.
Shortcut For running Riak node
I have written two shell script to ease for running Riak nodes.It is very ease to use in every day.
First, create riak_run.sh using text editor and add following lines and save:
#!/bin/bash
#script for initiating riak database.
echo "Initiating Riak DB..."
cd riak-1.3.2/dev/
for node in `ls`; do $node/bin/riak start; done
echo "Riak DB initiated."
echo "-----------------"
echo "Checking Riak....."
ps aux | grep beam
echo "Riak checking completed."
Second, create riak_stop.sh file, add and save below lines:
#!/bin/bash
#script for initiating riak database.
echo "Stoping Riak DB..."
cd riak-1.3.2/dev/
for node in `ls`; do $node/bin/riak stop; done
echo "Riak DB stoped."
echo "-----------------"
echo "Checking Riak....."
ps aux | grep beam
echo "Riak checking completed."
must save this two files in home directory and run the below command in your Teminal:
make it as executable
chmod +x riak_run.sh
chmod +x riak_stop.sh
For run and check the status of Riak nodes:
./riak_run.sh
For stop Riak nodes:
./riak_stop.sh
Congratulations!....Cheers!!!!
Reference: http://docs.basho.com/riak
