openstack/swift
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Update EC Support on how to build an EC ring with replicas count

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This doc is being updated to specify the replicas count parameter
to build an EC ring that enforces both data and parity placements
for each partition.

Change-Id: I770ad268e4017e610be3357e89b89f0b7d3c18af
Closes-Bug: 1487203
This commit is contained in:
Bill Huber 2015-09-14 16:01:39 -05:00 committed by Alistair Coles
parent e6937b8947
commit 530102ae07
1 changed files with 16 additions and 3 deletions
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19
doc/source/overview_erasure_code.rst
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@ -251,9 +251,22 @@ of them will be made of parity data (calculations depending on ec_type).
When deciding which devices to use in the EC policy's object ring, be sure to
carefully consider the performance impacts. Running some performance
benchmarking in a test environment for your configuration is highly recommended
before deployment. Once you have configured your EC policy in `swift.conf` and
created your object ring, your application is ready to start using EC simply by
creating a container with the specified policy name and interacting as usual.
before deployment.
To create the EC policy's object ring, the only difference in the usage of the
``swift-ring-builder create`` command is the ``replicas`` parameter. The
``replicas`` value is the number of fragments spread across the object servers
associated with the ring; ``replicas`` must be equal to the sum of
``ec_num_data_fragments`` and ``ec_num_parity_fragments``. For example::
swift-ring-builder object-1.builder create 10 14 1
Note that in this example the ``replicas`` value of 14 is based on the sum of
10 EC data fragments and 4 EC parity fragments.
Once you have configured your EC policy in `swift.conf` and created your object
ring, your application is ready to start using EC simply by creating a container
with the specified policy name and interacting as usual.
.. note::