[lustre-discuss] Target names changing when mounting

[Drokin, Oleg]

Hello!

On Jul 31, 2015, at 2:08 PM, Andrus, Brian Contractor wrote:

> All,
>  
> I find this very confusing..
> I created a new lustre filesystem (WORK2) by creating and MDT and a single OST.
> When I first create them, the names shown for Target have different values from ‘Read precious values’ and ‘Permanent disk data’
> The difference is a hyphen ‘-‘ versus a colon ‘:’

This is internal bookkeeping to show target status:

        /* svname of the form lustre:OST1234 means never registered */
	rc = strlen(ldd->ldd_svname);
        if (ldd->ldd_svname[rc - 8] == ':') {
                ldd->ldd_svname[rc - 8] = '-';
                ldd->ldd_flags |= LDD_F_VIRGIN;
        } else if (ldd->ldd_svname[rc - 8] == '=') {
                ldd->ldd_svname[rc - 8] = '-';
                ldd->ldd_flags |= LDD_F_WRITECONF;
        }

>  
>    Read previous values:
> Target:     WORK2-MDT0000
>  
>    Permanent disk data:
> Target:     WORK2:MDT0000
>  
> The ext2 label on the disk matches the Permanent disk data.
> BUT….
> When I mount it (mount -t lustre) the Permanent disk data changes to use a colon and the e2label changes….
>    Read previous values:
> Target:     WORK2-MDT0000
>  
>    Permanent disk data:
> Target:     WORK2-MDT0000
>  
> THEN…
> If I do a tunefs.lustre --writeconf , it changes the Permanent disk data AND the e2label to use an equal ‘=’ sign:
>  
>    Read previous values:
> Target:     WORK2-MDT0000
>  
>    Permanent disk data:
> Target:     WORK2=MDT0000
>  
> Next time I mount it changes it back to the hyphen ‘-‘
> So.. What the heck???

Matches the code so far.
 
> Now the problem/annoyance is the fact that this changes links in /dev…

What links? This is internal lustre target name, your block device
name should still stay the same as it was.

> And an equal sign ‘=’ is NOT a happy character for device names…
> I am also highly suspicious this affects some of the mappings in the MGS and MDT which is causing great grief…

Should not, really, since this is expected and we treat those changes as meaningful to
indicate the target status.

Bye,
    Oleg