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List: veritas-ha
Subject: Re: [Veritas-ha] I/O Fencing non-CFS
From: Gene Henriksen <gene_henriksen () symantec ! com>
Date: 2010-10-13 16:42:16
Message-ID: 3469AF22E7D82A46A12B6612437B8DF56500B470 () TUS1XCHEVSPIN38 ! SYMC ! SYMANTEC ! COM
[Download RAW message or body]
The server that had it imported would not notice the change.. Both servers =
can access the storage.
If you didn't have link-lowpri, then bringing up the IP would probably stop=
the process as it got a ping on the other IP already running.
________________________________
From: veritas-ha-bounces@mailman.eng.auburn.edu [mailto:veritas-ha-bounces@=
mailman.eng.auburn.edu] On Behalf Of Everett Henson
Sent: Wednesday, October 13, 2010 11:40 AM
To: Gene Henriksen; 'veritas-ha@mailman.eng.auburn.edu'
Subject: Re: [Veritas-ha] I/O Fencing non-CFS
Thanks Gene. I understand it's possible to import the group manually, but t=
he discussion here was around how VCS would behave normally, without manual=
intervention. Wouldn't a vxdg -C to clear the private region give the serv=
er with the group already imported heartburn? Would it allow both servers s=
imultaneous access to the storage?
BTW, We are using two private interconnects as well as a link-lowpri alread=
y.
From: Gene Henriksen [mailto:gene_henriksen@symantec.com]
Sent: Wednesday, October 13, 2010 11:34 AM
To: Everett Henson; 'veritas-ha@mailman.eng.auburn.edu'
Subject: RE: I/O Fencing non-CFS
IO Fencing works with VCS. Even without CFS/RAC it is the best protection a=
gainst split-brain. You CAN import a DG on multiple systems by using vxdg -=
C import <dg> to clear the name in the private region.
Alternatives include the preonline_ipc trigger (in sample_triggers, copy to=
triggers, rename preonline and enable PreOnline in service groups). Also l=
ink-lowpri.
________________________________
From: veritas-ha-bounces@mailman.eng.auburn.edu [mailto:veritas-ha-bounces@=
mailman.eng.auburn.edu] On Behalf Of Everett Henson
Sent: Wednesday, October 13, 2010 11:04 AM
To: 'veritas-ha@mailman.eng.auburn.edu'
Subject: [Veritas-ha] I/O Fencing non-CFS
Group,
There has been a discussion in my workplace over the usefulness of I/O Fenc=
ing in the absence of CFS or Oracle RAC. The question is whether I/O Fencin=
g is necessary when Standard Storage Foundation is being used. My understan=
ding is that without CFS or RAC, only one node can have a Disk Group import=
ed at a time, and even in the event of split brain, no two servers can have=
the same access to the same storage simultaneously. Any attempt by one ser=
ver to import storage already imported on another server should result in a=
FAULT or an error.
In all the documentation on Veritas I've read over the years, I/O Fencing i=
s only mentioned in connection with shared storage, and never with standard=
SF.
So, what is the consensus, does implementing I/O Fencing with Standard SF p=
rovide any advantage?
Everett Henson
________________________________
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Visit our website at http://www.nyse.com
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Note: The information contained in this message and any attachment to it is=
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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>The server that had it imported would not
notice the change.. Both servers can access the storage.<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><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>If you didn’t have link-lowpri, then
bringing up the IP would probably stop the process as it got a ping on the
other IP already running.<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>
<div>
<div class=MsoNormal align=center style='text-align:center'><font size=3
face="Times New Roman"><span style='font-size:12.0pt;font-family:"Times New Roman"'>
<hr size=3 width="100%" align=center tabindex=-1>
</span></font></div>
<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'> \
veritas-ha-bounces@mailman.eng.auburn.edu \
[mailto:veritas-ha-bounces@mailman.eng.auburn.edu] <b><span style='font-weight: \
bold'>On Behalf Of </span></b>Everett Henson<br> <b><span \
style='font-weight:bold'>Sent:</span></b> Wednesday, October 13, 2010 11:40 AM<br>
<b><span style='font-weight:bold'>To:</span></b> Gene Henriksen;
'veritas-ha@mailman.eng.auburn.edu'<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [Veritas-ha] I/O
Fencing non-CFS</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 color="#1f497d" face=Calibri><span
style='font-size:11.0pt;color:#1F497D'>Thanks Gene. I understand it’s possible
to import the group manually, but the discussion here was around how VCS would
behave normally, without manual intervention. Wouldn’t a vxdg –C to clear \
the private region give the server with the group already imported heartburn? Would
it allow both servers simultaneous access to the \
storage?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span
style='font-size:11.0pt;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span
style='font-size:11.0pt;color:#1F497D'>BTW, We are using two private
interconnects as well as a link-lowpri already. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span
style='font-size:11.0pt;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span
style='font-size:11.0pt;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span
style='font-size:11.0pt;color:#1F497D'><o:p> </o:p></span></font></p>
<div>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<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'> Gene Henriksen \
[mailto:gene_henriksen@symantec.com] <br>
<b><span style='font-weight:bold'>Sent:</span></b> Wednesday, October 13, 2010
11:34 AM<br>
<b><span style='font-weight:bold'>To:</span></b> Everett Henson;
'veritas-ha@mailman.eng.auburn.edu'<br>
<b><span style='font-weight:bold'>Subject:</span></b> RE: I/O Fencing \
non-CFS<o:p></o:p></span></font></p>
</div>
</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 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>IO Fencing works with VCS. Even without
CFS/RAC it is the best protection against split-brain. You CAN import a DG on
multiple systems by using vxdg –C import <dg> to clear the name in the
private region.<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><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Alternatives include the preonline_ipc
trigger (in sample_triggers, copy to triggers, rename preonline and enable
PreOnline in service groups). Also link-lowpri.<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>
<div>
<div class=MsoNormal align=center style='text-align:center'><font size=3
face="Times New Roman"><span style='font-size:12.0pt;font-family:"Times New Roman"'>
<hr size=3 width="100%" align=center>
</span></font></div>
<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'>
veritas-ha-bounces@mailman.eng.auburn.edu
[mailto:veritas-ha-bounces@mailman.eng.auburn.edu] <b><span style='font-weight:
bold'>On Behalf Of </span></b>Everett Henson<br>
<b><span style='font-weight:bold'>Sent:</span></b> Wednesday, October 13, 2010
11:04 AM<br>
<b><span style='font-weight:bold'>To:</span></b>
'veritas-ha@mailman.eng.auburn.edu'<br>
<b><span style='font-weight:bold'>Subject:</span></b> [Veritas-ha] I/O Fencing
non-CFS</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'>Group,<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'>There
has been a discussion in my workplace over the usefulness of I/O Fencing in the
absence of CFS or Oracle RAC. The question is whether I/O Fencing is necessary
when Standard Storage Foundation is being used. My understanding is that
without CFS or RAC, only one node can have a Disk Group imported at a time, and
even in the event of split brain, no two servers can have the same access to
the same storage simultaneously. Any attempt by one server to import storage
already imported on another server should result in a FAULT or an \
error.<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'>In
all the documentation on Veritas I’ve read over the years, I/O Fencing is only
mentioned in connection with shared storage, and never with standard \
SF.<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'>So,
what is the consensus, does implementing I/O Fencing with Standard SF provide
any advantage? <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><st1:City w:st="on"><st1:place w:st="on"><font size=2
face=Calibri><span \
style='font-size:11.0pt'>Everett</span></font></st1:place></st1:City> \
Henson<o:p></o:p></p>
<div class=MsoNormal align=center style='text-align:center'><font size=3
face="Times New Roman"><span style='font-size:12.0pt;font-family:"Times New Roman"'>
<hr size=1 width="100%" align=center>
</span></font></div>
<p><strong><b><font size=3 color=green face="Times New Roman"><span
style='font-size:12.0pt;color:green'>Please consider the environment before
printing this email.</span></font></b></strong><o:p></o:p></p>
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<strong><b><font face="Times New \
Roman">***************************************************************************** \
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confidential and protected from disclosure. If the reader of this message is not the \
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<pre><font size=2 face="Courier New"><span \
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<strong><b><font face="Times New \
Roman">***************************************************************************** \
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information contained in this message and any attachment to it is privileged, \
confidential and protected from disclosure. If the reader of this message is not the \
intended recipient, or an employee or agent responsible for delivering this message \
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<pre><font size=2 face="Courier New"><span \
style='font-size:10.0pt'><o:p> </o:p></span></font></pre></div>
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