swift/doc/source/policies_saio.rst
Paul Luse e52e8bc917 Add Storage Policy Documentation
Add overview and example information for using Storage Policies.

DocImpact
Implements: blueprint storage-policies
Change-Id: I6f11f7a1bdaa6f3defb3baa56a820050e5f727f1
2014-06-19 10:18:34 -07:00

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===========================================
Adding Storage Policies to an Existing SAIO
===========================================
Depending on when you downloaded your SAIO environment, it may already
be prepared with two storage policies that enable some basic functional
tests. In the event that you are adding a storage policy to an existing
installation, however, the following section will walk you through the
steps for setting up Storage Policies. Note that configuring more than
one storage policy on your development environment is recommended but
optional. Enabling multiple Storage Policies is very easy regardless of
whether you are working with an existing installation or starting a
brand new one.
Now we will create two policies - the first one will be a standard triple
replication policy that we will also explicitly set as the default and
the second will be setup for reduced replication using a factor of 2x.
We will call the first one 'gold' and the second one 'silver'. In this
example both policies map to the same devices because it's also
important for this sample implementation to be simple and easy
to understand and adding a bunch of new devices isn't really required
to implement a usable set of policies.
1. To define your policies, add the following to your ``/etc/swift/swift.conf``
file::
[storage-policy:0]
name = gold
default = yes
[storage-policy:1]
name = silver
See :doc:`overview_policies` for detailed information on ``swift.conf`` policy
options.
2. To create the object ring for the silver policy (index 1), add the following
to your ``bin/remakerings`` script and re-run it (your script may already have
these changes)::
swift-ring-builder object-1.builder create 10 2 1
swift-ring-builder object-1.builder add r1z1-127.0.0.1:6010/sdb1 1
swift-ring-builder object-1.builder add r1z2-127.0.0.1:6020/sdb2 1
swift-ring-builder object-1.builder add r1z3-127.0.0.1:6030/sdb3 1
swift-ring-builder object-1.builder add r1z4-127.0.0.1:6040/sdb4 1
swift-ring-builder object-1.builder rebalance
Note that the reduced replication of the silver policy is only a function
of the replication parameter in the ``swift-ring-builder create`` command
and is not specified in ``/etc/swift/swift.conf``.
3. Copy ``etc/container-reconciler.conf-sample`` to
``/etc/swift/container-reconciler.conf`` and fix the user option::
cp etc/container-reconciler.conf-sample /etc/swift/container-reconciler.conf
sed -i "s/# user.*/user = $USER/g" /etc/swift/container-reconciler.conf
------------------
Using Policies
------------------
Setting up Storage Policies was very simple, and using them is even
simpler. In this section, we will run some commands to create a few
containers with different policies and store objects in them and see how
Storage Policies effect placement of data in Swift.
1. We will be using the list_endpoints middleware to confirm object locations,
so enable that now in your ``proxy-server.conf`` file by adding it to the pipeline
and including the filter section as shown below (be sure to restart your proxy
after making these changes)::
pipeline = catch_errors gatekeeper healthcheck proxy-logging cache bulk \
slo dlo ratelimit crossdomain list-endpoints tempurl tempauth staticweb \
container-quotas account-quotas proxy-logging proxy-server
[filter:list-endpoints]
use = egg:swift#list_endpoints
2. Check to see that your policies are reported via /info::
swift -A http://127.0.0.1:8080/auth/v1.0 -U test:tester -K testing info
You should see this: (only showing the policy output here)::
policies: [{'default': True, 'name': 'gold'}, {'name': 'silver'}]
3. Now create a container without specifying a policy, it will use the
default, 'gold' and then put a test object in it (create the file ``file0.txt``
with your favorite editor with some content)::
curl -v -X PUT -H 'X-Auth-Token: <your auth token>' \
http://127.0.0.1:8080/v1/AUTH_test/myCont0
curl -X PUT -v -T file0.txt -H 'X-Auth-Token: <your auth token>' \
http://127.0.0.1:8080/v1/AUTH_test/myCont0/file0.txt
4. Now confirm placement of the object with the :ref:`list_endpoints` middleware::
curl -X GET -v http://127.0.0.1:8080/endpoints/AUTH_test/myCont0/file0.txt
You should see this: (note placement on expected devices)::
["http://127.0.0.1:6030/sdb3/761/AUTH_test/myCont0/file0.txt",
"http://127.0.0.1:6010/sdb1/761/AUTH_test/myCont0/file0.txt",
"http://127.0.0.1:6020/sdb2/761/AUTH_test/myCont0/file0.txt"]
5. Create a container using policy 'silver' and put a different file in it::
curl -v -X PUT -H 'X-Auth-Token: <your auth token>' -H \
"X-Storage-Policy: silver" \
http://127.0.0.1:8080/v1/AUTH_test/myCont1
curl -X PUT -v -T file1.txt -H 'X-Auth-Token: <your auth token>' \
http://127.0.0.1:8080/v1/AUTH_test/myCont1/
6. Confirm placement of the object for policy 'silver'::
curl -X GET -v http://127.0.0.1:8080/endpoints/AUTH_test/myCont1/file1.txt
You should see this: (note placement on expected devices)::
["http://127.0.0.1:6010/sdb1/32/AUTH_test/myCont1/file1.txt",
"http://127.0.0.1:6040/sdb4/32/AUTH_test/myCont1/file1.txt"]
7. Confirm account information with HEAD, make sure that your container-updater
service is running and has executed once since you performed the PUTs or the
account database won't be updated yet::
curl -i -X HEAD -H 'X-Auth-Token: <your auth token>' \
http://127.0.0.1:8080/v1/AUTH_test
You should see something like this (note that total and per policy stats
object sizes will vary)::
HTTP/1.1 204 No Content
Content-Length: 0
X-Account-Object-Count: 2
X-Account-Bytes-Used: 174
X-Account-Container-Count: 2
X-Account-Storage-Policy-Gold-Object-Count: 1
X-Account-Storage-Policy-Gold-Bytes-Used: 84
X-Account-Storage-Policy-Silver-Object-Count: 1
X-Account-Storage-Policy-Silver-Bytes-Used: 90
X-Timestamp: 1397230339.71525
Content-Type: text/plain; charset=utf-8
Accept-Ranges: bytes
X-Trans-Id: tx96e7496b19bb44abb55a3-0053482c75
Date: Fri, 11 Apr 2014 17:55:01 GMT