Posted! (after Sean reminded in IRC)
On 5/20/14, 12:56 PM, Josh Elser wrote:
Including plaintext for those who don't have a blog account (yet).
On 5/20/14, 12:40 PM, Josh Elser wrote:
All,
I took a few moments to write up some of the details surrounding changes
that took place in 1.6.0. It covers downloading a release from us, the
changes with native maps and how to build them, how to choose example
configurations and then init'ing and starting Accumulo
https://blogs.apache.org/roller-ui/authoring/preview/accumulo/?previewEntry=getting_started_with_apache_accumulo
Grammatical feedback and inaccuracies would be humbly accepted. This
will be open for feedback for 3 days (2014/05/23 1700 UTC) after which
I'll promote it to the main blog.
Thanks!
--- Plaintext draft content
Getting Started with Apache Accumulo 1.6.0
On May 12th, 2014, the Apache Accumulo project happily announced version
1.6.0 to the community. This is a new major release for the project
which contains many numerous new features and fixes. For the full list
of notable changes, I'd recommend that you check out the release notes
that were published alongside the release itself. For this post, I'd
like to cover some of the changes that have been made at the
installation level that are a change for users who are already familiar
with the project.
Download the release
Like always, you can find out releases on the our downloads page at
http://accumulo.apache.org/downloads/. You have the choice of
downloading the source and building it yourself, or choosing the binary
tarball which already contains pre-built jars for use.
Native Maps
One of the major components of the original BigTable design was an
"In-Memory Map" which provided fast insert and read operations. Accumulo
implements this using a C++ sorted map with a custom allocator which is
invoked by the TabletServer using JNI. Each TabletServer uses its own
"native" map. It is highly desirable to use this native map as it comes
with a notable performance increase over a Java map (which is the
fallback when the Accumulo shared library is not found) in addition to
greatly reducing the TabletServer's JVM garbage collector stress when
ingesting data.
In previous versions, the binary tarball contained a pre-compiled
version of the native library (under lib/native/). Shipping a compiled
binary was a convenience but also left much confusion when it didn't
work on systems which had different, incompatible versions of GCC
toolchains installed than what the binary was built against. As such, we
have stopped bundling the pre-built shared library in favor of users
building this library on their own, and instead include an
accumulo-native.tar.gz file within the lib directory which contains the
necessary files to build the library yourself.
To reduce the burden on users, we've also introduced a new script inside
of the bin directory:
build_native_map.sh
Invoking this script will automatically unpack, build and install the
native map in $ACCUMULO_HOME/lib/native. If you've used older versions
of Accumulo, you will also notice that the library name is different in
an attempt to better follow standard conventions: libaccumulo.so on
Linux and libaccumulo.dylib on Mac OS X.
Example Configurations
Apache Accumulo still bundles a set of example configuration files in
conf/examples. Each sub-directory contains the complete set of files to
run on a single node with the named memory limitations. For example, the
files contained in conf/examples/3GB/native-standalone will run Accumulo
on a single node, with native maps (don't forget to build them first!),
within a total memory footprint of 3GB. Copy the contents of one of
these directories into conf/ and make sure that your relevant
installation details (e.g. HADOOP_PREFIX, JAVA_HOME, etc) are properly
set in accumulo-env.sh.
The change in these scripts is that they default to using Apache Hadoop
2 packaging details, such as the Hadoop conf directory and jar
locations. It is highly recommended by the community that you use Apache
Accumulo 1.6.0 with at least Apache Hadoop 2.2.0, most notably, to
ensure that you will not lose data in the face of power failure. If you
are still running on a Hadoop 1 release (1.2.1), you will need to edit
both accumulo-env.sh and accumulo-site.xml. There are comments in each
file which instruct you what needs to be changed.
Starting Accumulo
Initializing and starting Accumulo hasn't changed at all! After you have
created the configuration files and, if you're using them, built the
native maps, run:
accumulo init
This will prompt you to name your Accumulo instance and set the Accumulo
root user's password, then start Accumulo using
$ACCUMULO_HOME/bin/start-all.sh
