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volume tuning

Question asked by brian on Aug 11, 2011
Latest reply on Aug 11, 2011 by Ted Dunning
I have a small test 5 node cluster. Each node has 16 CPU, 64GB and 12 * 2TB drives available to mapr.

I configured one volume with a replication factor of 3.  I have been testing write speeds and updates to files in this volume and noticed via the mapr cluster console (the web thingy on :8443) a couple things which have me wondering a few things as well:

 1. the one volume is only leveraging 3 of the 5 nodes in the cluster.  I assume this is because the rep. factor set to 3.  So each of these 3 nodes has complete information for the volume?
 2. on each of the 3 hosts, only 3 of the 12 disks are used for the volume.  this is particularly troublesome to me as I'd like to leverage more spindles and get more iops out of this volume.  I would like to allocate / tune this volume.  Is this possible?  How does one do it.
  I know someone will pounce on this item and make a plea to me to make more volumes.  doing so has the undesirable side effect of creating more directories, obviously.  I don't want to burden my applications to partition their data evenly across subdirectories.

a general comment / question -
is there a secret trove of documentation somewhere?  the docs on the mapr website are pretty simple and as such cover only the most basic of matters.

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