[LU-15418] I need clarification on using lctl replace_nids Created: 06/Jan/22  Updated: 04/Aug/22

Status: Open
Project: Lustre
Component/s: None
Affects Version/s: Lustre 2.12.8
Fix Version/s: None

Type: Question/Request Priority: Blocker
Reporter: Roger Sersted Assignee: Artem Blagodarenko
Resolution: Unresolved Votes: 0
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


Issue Links:
Duplicate
duplicates LUDOC-523 add proper documentation for replace_... Open
Epic/Theme: lnet
Rank (Obsolete): 9223372036854775807

 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.



 Comments   
Comment by Andreas Dilger [ 07/Jan/22 ]

There is some brief description of the replace_nids command in LU-11846, and a request to the author of that command to provide a separate lctl-replace_nids.8 man page that has a more complete description of that command, and preferably with some usage examples.

Comment by Roger Sersted [ 12/Jan/22 ]

I successfully used the writeconf method to move the OSTs to different servers.

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