[LU-15418] I need clarification on using lctl replace_nids

• Type: Question/Request
• Resolution: Unresolved
• Priority: Blocker
• Affects Version/s: Lustre 2.12.8
• Labels: lctl
• Environment: Clients 2.12.7 - CentOS 7.9 ; Current Lustre servers - 2.12.7 kernel-3.10.0-1160.25.1.el7_lustre.x86_64 ; New Lustre Server - 2.12.8 kernel-3.10.0-1160.49.1.el7_lustre.x86_64

Epic/Theme

lnet

• Assignee: Artem Blagodarenko
• Reporter: Roger Sersted

Description

I'm moving some OSTs to a different server within the same subnet as my existing Lustre servers, so the module configs won't change.  However, the man page replace_nids is really vague.

Given the following:

lctl list_nids  #current server

172.17.1.104@o2ib
172.16.1.104@tcp

Current failover NIDs

172.17.1.105@o2ib
172.16.1.106@tcp

And the new OSS

172.17.1.236@o2ib
172.16.1.236@tcp

New Failover OSS

172.17.1.237@o2ib
172.16.1.237@tcp

The device would be lustrefc-OST000e

Would this be the correct command

lctl replace_nids lustrefc-OST000e \ 172.17.1.236@o2ib,172.16.1.236@tcp:172.17.1.237@o2ib,172.16.1.237@tcp

The above command would be run on the MGS server and the MGT is the only service mounted/running.  I'll be moving about 8 OSTs.  I'm guessing I should run my commands, then unmount the MGS.  Then start Lustre in this order, MGT, MDT then OSTs in ascending order.  Correct?

The filesystem is down for maintenance.  This is my final step before bringing it online.  Thank you.

Issue Links

• duplicates: LUDOC-523 add proper documentation for replace_nids command