[lustre-discuss] Mor eon repointing MDS and OSS services to a new MGS

[Andreas Dilger]

On Oct 23, 2025, at 17:35, Sid Young via lustre-discuss <lustre-discuss at lists.lustre.org> wrote:

G'Day all,

Following on from my earlier post and reviewing the responses I received (thanks for responding), I've done further research on migrating to a new MGS, am I correct that there is no actual data in an MGS until the underlying services register themselves with it?

In other words, can I just repoint my legacy CENTOS 7.9/Lustre 2.12 MDS/MDTs and OSS/OSTs to the new mgs node running a later lustre version on a newer supported OS platform, then repoint the clients to the new MGS and simply not mount the old CENTOS MGS?

The important information on the MGS is the configuration parameters, OST Pool config, etc.

You can regenerate the basic filesystem config with a "writeconf" process (per Lustre Operations Manual).

Any tunable parameters would be lost if the MGT is not copied, unless you do a backup+restore of them.
I _think_ it is enough to use "lctl --device MGS llog_print params" to dump the "set_param" parameters,
and same for "... FSNAME-MDT0000" and "... FSNAME-OST0000" and "... FSNAME-client" to dump the
(deprecated) "conf_param" parameters.

Cheers, Andreas
—
Andreas Dilger
Lustre Principal Architect
Whamcloud/DDN




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