We’ve kept parallel clusters on the same network for nearly a year now while transitioning to RH7 from CentOS 6. Initially copied the hosts and nodelist and MAC tables into the new xcat database. Carefully controlled use of makedhcp so that nodes moving to the new cluster were first added to new dhcp server and then deleted from the old. ( Didn’t want a repeat of what happened when I left some deleted from the old but not added to the new cluster and they lost their lease. The postscript hardeths also helped. ). Make new images and use nodeset to point to them. Reboot and test.
Drawback is having to make parallel changes on both management servers all the time, but we needed both clusters to access gpfs so it was a necessary evil. -- ddj Dave Johnson > On Dec 6, 2018, at 4:23 PM, Kevin Keane <kke...@sandiego.edu> wrote: > > I'm in the middle of upgrading our existing HPC (from RHEL 6 to RHEL 7). I'm > doing most of my testing on a separate "sandbox" test bed, but now I'm close > to going live. I'm trying to figure out how to do this with minimal > disruption. > > My question: how can I install the new management node and keep it *almost* > completely operational, without interfering with the existing cluster? Is it > enough to disable DHCP, or do I need to do anything else? > > How do I prevent DHCP from accidentally getting enabled before I'm ready? Is > makedhcp responsible for that? > > Step-by-step, here is what I plan to do: > > - Set up the new management node, but keep it inactive. > - Test > - Bring down all compute nodes. > - Via IPMI, reset all the compute nodes' BMC controllers to DHCP > - Other migration steps (home directories, modifications on the storage node, > etc.) > - De-activate the old management node (but keep it running) > - Activate the new management node. > - Discover and boot compute nodes > > Is there anything glaringly obvious that I overlooked? > > Thanks! > _______________________________________________________________________ > Kevin Keane | Systems Architect | University of San Diego ITS | > kke...@sandiego.edu > Maher Hall, 192 |5998 Alcalá Park | San Diego, CA 92110-2492 | 619.260.6859 > > REMEMBER! No one from IT at USD will ever ask to confirm or supply your > password. > These messages are an attempt to steal your username and password. Please do > not reply to, click the links within, or open the attachments of these > messages. Delete them! > > > > _______________________________________________ > xCAT-user mailing list > xCAT-user@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/xcat-user
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