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<div class="moz-cite-prefix">On 13/06/13 10:37, Dan Barker wrote:<br>
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<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">rsync
will not be able to synchronize from a “failed” disk, drbd
already has done so.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Dan
in Atlanta<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext">
<a class="moz-txt-link-abbreviated" href="mailto:drbd-user-bounces@lists.linbit.com">drbd-user-bounces@lists.linbit.com</a>
[<a class="moz-txt-link-freetext" href="mailto:drbd-user-bounces@lists.linbit.com">mailto:drbd-user-bounces@lists.linbit.com</a>]
<b>On Behalf Of </b>Robinson, Eric<br>
<b>Sent:</b> Wednesday, June 12, 2013 6:20 PM<br>
<b>To:</b> Dirk Bonenkamp - ProActive<br>
<b>Cc:</b> <a class="moz-txt-link-abbreviated" href="mailto:drbd-user@lists.linbit.com">drbd-user@lists.linbit.com</a><br>
<b>Subject:</b> Re: [DRBD-user] drbd+mysql+innodb<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hi
Dirk – Thanks for the feedback. I do need some
clarification, though. DRBD replicates disk block changes
to a standby volume. If the primary node suddenly fails,
the cluster manager promotes the standby node to primary
and starts the MySQL service. Logically, this seems
exactly the same as simply rsyncing the data to the new
server and starting the MySQL service. Why would it work
with DRBD but not with rsync? Thanks for your patience
while I explore this.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Note:
we have over 500 separate MySQL database instances using
MyISAM. I am totally not stoked about the idea of using
300% more disk space and gobs more memory.<o:p></o:p></span></p>
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I think the real issue with rsync is that it will start copying the
file, but new writes may come in during the copy process, therefore
the destination copy is not a point in time copy of the source. This
is the same issue with using rsync for disk images of VM's that are
running during the rsync. As explained, this is not an issue for
DRBD replication, because at any instant in time, the replica
(destination copy) is an exact copy of the source at some point in
time, even if it is not the latest point in time.<br>
<br>
Regards,<br>
Adam<br>
<br>
<pre class="moz-signature" cols="72">--
Adam Goryachev
Website Managers
<a class="moz-txt-link-abbreviated" href="http://www.websitemanagers.com.au">www.websitemanagers.com.au</a>
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