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<p class="MsoPlainText"><span lang="EN-US">Sorry if my question is not clear.<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US">When I create a new replicated volume, using only 2 nodes, I use this command line : ‘gluster volume create
<i>vol_name</i> replica 2 transport tcp <i>server1</i>:/export/brick1/1 <i>server2</i>:/export/brick1/1’<o:p></o:p></span></p>
<p class="MsoPlainText"><i><span lang="EN-US">server1 </span></i><span lang="EN-US">and<i> server2</i> are in 2 different datacenters.
<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US">Now, if I want to expand gluster volume, using 2 new servers (ex :
<i>server3 </i>and<i> server4)</i> , I use those command lines : <o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US">‘gluster volume add-brick <i>vol_name</i> server3: /export/brick1/1’<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US">‘gluster volume add-brick <i>vol_name</i> server4: /export/brick1/1’<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US">‘gluster volume rebalance <i>vol_name</i> fix-layout start’<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US">‘gluster volume rebalance <i>vol_name </i>
start’<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US">How the rebalance command work ?<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US">How to be sure that replicated data are not stored on servers hosted in the same datacenter ?<o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoPlainText"><span lang="EN-US">Sébastien<o:p></o:p></span></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText"><span style="mso-fareast-language:FR">-----Message d'origine-----<br>
De : Jeff Darcy [mailto:jdarcy@redhat.com] <br>
Envoyé : vendredi 18 avril 2014 18:52<br>
À : COCHE Sébastien<br>
Cc : gluster-users@gluster.org<br>
Objet : Re: [Gluster-users] Glusterfs Rack-Zone Awareness feature...</span></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">> I do not understand why it could be a problem to place the data's
<o:p></o:p></p>
<p class="MsoPlainText">> replica on a different node group.<o:p></o:p></p>
<p class="MsoPlainText">> If a group of node become unavailable (due to datacenter failure, for<o:p></o:p></p>
<p class="MsoPlainText">> example) volume should remain online, using the second group.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">I'm not sure what you're getting at here. If you're talking about initial placement of replicas, we can place all members of each replica set in different node groups (e.g. racks). If you're talking about adding new replica members
when a previous one has failed, then the question is *when*.<o:p></o:p></p>
<p class="MsoPlainText">Re-populating a new replica can be very expensive. It's not worth starting if the previously failed replica is likely to come back before you're done.<o:p></o:p></p>
<p class="MsoPlainText">We provide the tools (e.g. replace-brick) to deal with longer term or even permanent failures, but we don't re-replicate automatically. Is that what you're talking about?<o:p></o:p></p>
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