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<div class=Section1>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Simon,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>This one actually was. <span
style='mso-spacerun:yes'> </span>And Phil took a different approach where we
would use the <span class=SpellE>usermode_helper</span>. Below is that exchange
for completeness:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'>Ernest,<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'>Over
the weekend I realized that the split brain event is quite similar to a number
of events we already signal back to <span class=SpellE>userspace</span>.<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'>The
invocation of handlers is also visible through the "<span class=SpellE>drbdsetup</span>
events"<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><span
class=GramE><font size=2 face="Courier New"><span style='font-size:10.0pt;
font-family:"Courier New"'>interface</span></font></span><font size=2
face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'>.<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'>The
attached patch creates <span class=GramE>an</span> handler called
"split-brain". If you can live with that interface as well, I will
commit that...<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'>In
the future I want to go this way:<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'><span
style='mso-spacerun:yes'> </span>* Allow one to set the <span class=SpellE>usermode_helper</span>
to the empty string. Then it <o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'><span
style='mso-spacerun:yes'> </span><span class=GramE>is</span> still possible
to get all events through the "<span class=SpellE>drbdsetup</span>
events"<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'><span
style='mso-spacerun:yes'> </span><span class=GramE>interface</span>.<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'><span
style='mso-spacerun:yes'> </span>* The "outdate-peer" <span
class=SpellE>usermode_helper</span> sends an exit code back<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'><span
style='mso-spacerun:yes'> </span><span class=GramE>to</span> kernel space.
This is not yet possible when one only uses<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'><span
style='mso-spacerun:yes'> </span><span class=GramE>the</span> "<span
class=SpellE>drbdsetup</span> events" interface. This should get fixed.<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'>-Phil<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'>--
<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'>:
<span class=SpellE>Dipl-Ing</span> Philipp <span class=SpellE>Reisner</span><span
style='mso-spacerun:yes'> </span>Tel +43-1-8178292-<span
class=GramE>50 :</span><o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'>:
LINBIT Information Technologies GmbH<span style='mso-spacerun:yes'>
</span>Fax +43-1-8178292-<span class=GramE>82 :</span><o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'>:
<span class=SpellE>Vivenotgasse</span> 48, 1120 <st1:place w:st="on"><st1:City
w:st="on">Vienna</st1:City>, <st1:country-region w:st="on">Austria</st1:country-region></st1:place><span
style='mso-spacerun:yes'> </span><span style='mso-spacerun:yes'> </span><a
href="http://www.linbit.com/">http://www.linbit.com</a> :<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'>_______________________________________________<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><span
class=SpellE><span class=GramE><font size=2 face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New"'>drbd</span></font></span></span><span
class=GramE><font size=2 face="Courier New"><span style='font-size:10.0pt;
font-family:"Courier New"'>-dev</span></font></span><font size=2
face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'>
mailing list<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'>drbd-dev@lists.linbit.com<o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'><a
href="http://lists.linbit.com/mailman/listinfo/drbd-dev">http://lists.linbit.com/mailman/listinfo/drbd-dev</a><o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> drbd-dev-bounces@linbit.com
[mailto:drbd-dev-bounces@linbit.com] <b><span style='font-weight:bold'>On
Behalf Of </span></b>Graham, Simon<br>
<b><span style='font-weight:bold'>Sent:</span></b> Friday, January 11, 2008
10:25 AM<br>
<b><span style='font-weight:bold'>To:</span></b> drbd-dev@linbit.com<br>
<b><span style='font-weight:bold'>Subject:</span></b> [Drbd-dev] [DRBD-8.0
PATCH] Add split-brain event to netlink</span></font><font size=3
face="Times New Roman"><span style='font-size:12.0pt;font-family:"Times New Roman"'><o:p></o:p></span></font></p>
</div>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'>I’m
not sure if this was previously submitted or not, but this change adds an
explicit split-brain event to the netlink notifications so that user mode code
can know when a split-brain situation is encountered.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'>Simon<o:p></o:p></span></font></p>
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