frameworks_base/docs/html/guide/topics/data/testingbackup.jd

page.title=Testing Backup and Restore
page.tags=backup, marshmallow, androidm
page.keywords=backup, restore, testing

@jd:body

<div id="qv-wrapper">
<div id="qv">
  <h2>In this document</h2>
  <ol>
    <li><a href="#HowBackupWorks">How backup works</a></li>
    <li><a href="#Prerequisites">Prerequisites</a></li>
    <li><a href="#Preparing">Preparing your device or emulator</a></li>
    <li><a href="#TestingBackup">Testing backup</a></li>
    <li><a href="#TestingRestore">Testing restore</a></li>
    <li><a href="#Troubleshooting">Troubleshooting</a></li>
  </ol>

</div>
</div>

<p>This page shows you how to manually trigger Auto Backup, Key/Value Backup, and restore operations to
ensure your app saves and restores data properly.

<h2 id="HowBackupWorkso">How backup works</h2>
<p>The section describes various pieces in the Android backup framework and how they
interact with apps that support Auto Backup and Key/Value Backup. During the app
development phase, most of the inner working of the framework were abstracted away, so you didn't need to know this information. However, during the
testing phase, an understanding of these concepts is important.

<p>The following diagram illustrates how data flows during backup and restore:

<img src="images/backup-framework.png" alt="backup-framework">

<p>The <em>Backup Manager Service</em> is an Android system
service which orchestrates and initiates backup and restore operations. The service
is accessible through the {@link android.app.backup.BackupManager}
API. During a backup operation, the service queries your app for backup data,
then hands it to the <em>backup transport</em>, which then archives the data.
During a restore operation, the backup manager service retrieves the backup data
from the backup transport and restores the data to the device.

<p><em>Backup Transports</em> are Android components that are responsible
for storing and retrieving backups. An Android device can have zero or more
backup transports, but only one of those transports can be marked active. The
available backup transports may differ from device to device (due to
customizations by device manufacturers and service providers), but most Google
Play enabled devices ship with the following transports:
</p><ul>
<li><strong>Google GMS Transport</strong>(default) - the active backup
transport on most devices, part of <a href="https://www.android.com/gms/">Google Mobile Services</a>. This documentation assumes that users are using the
Google GMS transport. This transport stores Auto Backup data in a private folder in the
user's Google Drive account. Key/Value Backup data is stored in the <a href="{@docRoot}google/backup/index.html">Android Backup Service</a>.
<li><strong>Local Transport</strong> - stores backup data locally on the device.
This transport is typically used for development/debugging purposes and is not
useful in the real world.</li></ul>

<p>If a device does not have any backup transports, then the data cannot be
backed up. Your app is not adversely affected.

<p class="caution"><strong>Caution:</strong> Because the backup transport
can differ from device to device, Android cannot guarantee the security
of your data while using backup. Be cautious about using backup to store
sensitive data, such as usernames and passwords.

<h2 id="Prerequisites">Prerequisites</h2>
<p>You need to know a bit about the following tools:

<ul>
  <li><a href="{@docRoot}studio/command-line/adb.html">adb</a>
- to run commands on the device or emulator
  <li><a href="{@docRoot}studio/command-line/bmgr.html">bmgr</a> - to
perform various backup and restore operations
  <li><a href="{@docRoot}studio/command-line/logcat.html">logcat</a>
- to see the output of backup and restore operations.</li></ul>

<h2 id="Preparing">Preparing your device or
emulator</h2>
<p>Prepare your device or emulator for backup testing by working through the
following checklist:
<ul>
  <li>For Auto Backup, check that you are using a device or emulator running
Android 6.0 (API level 23) or higher.</li>
  <li>For Key/Value Backup, check that you are using a device or emulator running
Android 2.2 (API level 8) or higher.</li>
  <li>Check that backup and restore is enabled on the device or emulator. There
are two ways to check: <ul>
    <li>On the device, go to <strong>Settings -> Backup &amp; Restore</strong>.
    <li>From adb shell, run <code>bmgr enable</code></li></ul>
    <p>On physical devices, backup and restore is typically enabled during the
initial setup wizard. Emulators do not run the setup wizard, so don't forget to
enable backup and specify a backup account in device settings.
  <li>Make sure the GMS Backup Transport is available and active by running the
command from adb shell:
  <pre class="prettyprint">$ bmgr list transports</pre>
  <p>Then, check the console for the following output:
  <pre class="prettyprint">android/com.android.internal.backup.LocalTransport
* com.google.android.gms/.backup.BackupTransportService</pre>
  <p>Physical devices without Google Play and emulators without Google APIs
might not include the GMS Backup Transport. This article assumes you are using
the GMS Backup Transport. You can test backup and restore with other backup
transports, but the procedure and output can differ.
</ul>

<h2 id="TestingBackup">Testing backup</h2>
<p>To initiate a backup of your app, run the following command:

<pre class="prettyprint">$ bmgr backupnow &lt;PACKAGE></pre>

<p>The <code>backupnow</code> command runs either a Key/Value Backup or Auto Backup depending on
the package's manifest declarations. Check logcat to see the output of the
backup procedure. For example:

<pre class="prettyprint">D/BackupManagerService: fullTransportBackup()
I/GmsBackupTransport: Attempt to do full backup on &lt;PACKAGE>

---- or ----

V/BackupManagerService: Scheduling immediate backup pass
D/PerformBackupTask: starting key/value Backup of BackupRequest{pkg=&lt;PACKAGE>}
</pre>

<p>If the <code>backupnow</code> command is not available on your device, you need to run one
of the following commands:
<ul>
  <li>For Auto Backups, run: <code>bmgr fullbackup &lt;PACKAGE></code>
  <li>For Key/Value Backups, schedule and run your backup with the following
commands:
  <pre class="prettyprint">$ bmgr backup &lt;PACKAGE>
$ bmgr run</pre>
  <p><code>bmgr backup</code> adds your app to the Backup Manager's queue. <code>bmgr run</code> initiates the
backup operation, which forces the Backup Manager to perform all backup requests
that are in its queue.
  </li></ul>

<h2 id="TestingRestore">Testing restore</h2>
<p>To manually initiate a restore, run the following command:

<pre class="prettyprint">$ bmgr restore &lt;PACKAGE></pre>

<p>Warning: This action stops your app and wipes its data before performing the
restore operation.

<p>Then, check logcat to see the output of the restore procedure. For example:

<pre class="prettyprint">V/BackupManagerService: beginRestoreSession: pkg=&lt;PACKAGE> transport=null
V/RestoreSession: restorePackage pkg=&lt;PACKAGE> token=368abb4465c5c683
...
I/BackupManagerService: Restore complete.
</pre>

<p>You also can test automatic restore for your app by uninstalling and
reinstalling your app either with <code>adb</code> or through the Google
Play Store app.

<h2 id="Troubleshooting">Troubleshooting</h2>
<p><strong>Exceeded Quota</strong>

<p>If you see the the following messages in logcat:

<pre class="prettyprint">I/PFTBT: Transport rejected backup of &lt;PACKAGE>, skipping

--- or ---

I/PFTBT: Transport quota exceeded for package: &lt;PACKAGE>
</pre>

<p>Your app has exceeded the quota and has been banned from backing up
data on this device. To lift the ban, either factory reset your device or change
the backup account.

<p><strong>Full Backup Not Possible</strong>

<p>If you see the the following message in logcat:

<pre class="prettyprint">I/BackupManagerService: Full backup not currently possible -- key/value backup not yet run?
</pre>

<p>The fullbackup operation failed because no Key/Value Backup operation has yet
occurred on the device. Trigger a Key/Value Backup with the command <code>bmgr
run </code>and then try again.