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<p class="MsoNormal"><span style="font-size:11.0pt">Hello everyone,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">We have an existing LFS that is dual-homed on ethernet (mainly for our workstations) and IB (for the computational cluster), ZFS backend for the MDT and OST's. We just got a new computational cluster and
need to add another IB NID. The procedure for doing this is straight forward (14.5 in the admin manual) and amounts to:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Unmount the clients<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Unmount the MDT<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Unmount all OSTs<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">mount -t lustre MDT partition -o nosvc mount_point<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">lctl replace_nids devicename nid1[,nid2,nid3 ...]<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">We haven't had to update a NID in a while so I was happy to see you can do this with "lctl replace_nids" instead of "tunsfs.lustre --writeconf". <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">I know this is dangerous, but we will sometime make minor changes to the servers by unmounting lustre on the servers (but leaving the clients up), make the changes, then remount the servers. If we are confident
we can do this quickly, the clients recover just fine. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">While this isn't such a minor change, I'm a little tempted to do that in this case since nothing will really change for the existing clients – they don't need the new NID. Am I asking for trouble here or
do you think I can get away with this? I'm not too concerned about the possibility of it taking too long and getting the existing clients evicted. I'm (obviously) more concerned about doing something that would lead to corrupting the FS. I should probably
schedule an outage and do this right but... :)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Darby<o:p></o:p></span></p>
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