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Accumulo >> mail # user >> deployment architecture

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Re: deployment architecture
On 1/5/14, 12:44 PM, Arshak Navruzyan wrote:
> Is there a document that describes best practices for Accumulo deployments?

I'm guessing the Accumulo user-manual[1] covers some of this, but I'm
not positive.

> In particular:
> 1.  Should you run Accumulo on HD data nodes and name nodes? (Is
> enabling HDFS short-circuit local reads a good idea?)

Datanodes and tasktrackers/nodemanagers, yes. I wouldn't run it on the
Namenode though.

> 2.  If so do you disable map/reduce for nodes that run Accumulo tservers?

With conscious awareness of your resource allocation (make sure there
are still physical resources for Accumulo) this should be fine, but be
careful if you're running a heavy M/R load.

> 3.  Is auto-splitting (by size) done in the real world or do most real
> apps have pre-set split points?

Adding some split points is probably always a good idea. Making sure
each tabletserver has at least a few tablets for your table is good,
after that, you can increase the size of the split threshold (default is
1GB) for that table so you get a good distribution of tablets/tservers
for the amount of data you're storing (100-200 tablets is a good
target). The splits themselves obviously depend on your data, though.

> 4.  Do you let Accumulo decide when to flush and compact or do people
> write these into their apps (based on their knowledge of app behavior)

Unless you have retention policies which are stringent upon data being
physically removed from disk (as opposed to not visible through
Accumulo's API), I'm not coming up with a reason that you would have to
automate flush/compact. If you're doing data age-off (e.g. keeping N
months of data, and rolling off the oldest day of data each data), it's
probably not a bad idea to just do a range compaction on that old day to
clean it up before your users are hitting your system full swing.

> I know the generic answer is "it all depends on your app/workload" but
> if anyone wants to still describe their environment it would be helpful.
> Thanks.

[1] http://accumulo.apache.org/1.5/accumulo_user_manual.html