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:

    name = gold
    aliases = yellow, orange
    default = yes
    name = silver

    See Storage 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- 1
    swift-ring-builder object-1.builder add r1z2- 1
    swift-ring-builder object-1.builder add r1z3- 1
    swift-ring-builder object-1.builder add r1z4- 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
    use = egg:swift#list_endpoints
  2. Check to see that your policies are reported via /info:

    swift -A -U test:tester -K testing info

    You should see this: (only showing the policy output here):

    policies: [{'aliases': 'gold, yellow, orange', 'default': True,
        'name': 'gold'}, {'aliases': 'silver', '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>' \
    curl -X PUT -v -T file0.txt -H 'X-Auth-Token: <your auth token>' \
  4. Now confirm placement of the object with the List Endpoints middleware:

    curl -X GET -v

    You should see this: (note placement on expected devices):

  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" \
    curl -X PUT -v -T file1.txt -H 'X-Auth-Token: <your auth token>' \
  6. Confirm placement of the object for policy ‘silver’:

    curl -X GET -v

    You should see this: (note placement on expected devices):

  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>' \

    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
    X-Openstack-Request-Id: tx96e7496b19bb44abb55a3-0053482c75
    Date: Fri, 11 Apr 2014 17:55:01 GMT