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     <h4 class="title">
      <a name="mysql-cluster-backup-troubleshooting">
      </a>
      25.6.8.4 NDB Cluster Backup Troubleshooting
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  <p>
   If an error code is returned when issuing a backup request, the
        most likely cause is insufficient memory or disk space. You
        should check that there is enough memory allocated for the
        backup.
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    Important
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   <p>
    If you have set
    <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-backupdatabuffersize">
     <code class="literal">
      BackupDataBufferSize
     </code>
    </a>
    and
    <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-backuplogbuffersize">
     <code class="literal">
      BackupLogBufferSize
     </code>
    </a>
    and their sum is greater than 4MB, then you must also set
    <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-backupmemory">
     <code class="literal">
      BackupMemory
     </code>
    </a>
    as well.
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  <p>
   You should also make sure that there is sufficient space on the
        hard drive partition of the backup target.
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  <p>
   <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4">
    <code class="literal">
     NDB
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   </a>
   does not support repeatable
        reads, which can cause problems with the restoration process.
        Although the backup process is
   <span class="quote">
    “
    <span class="quote">
     hot
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    ”
   </span>
   , restoring an
        NDB Cluster from backup is not a 100%
   <span class="quote">
    “
    <span class="quote">
     hot
    </span>
    ”
   </span>
   process. This is due to the fact that, for the duration of the
        restore process, running transactions get nonrepeatable reads
        from the restored data. This means that the state of the data is
        inconsistent while the restore is in progress.
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