glabel clarification

Johan Hendriks Johan at
Mon Oct 19 13:59:48 UTC 2009

>I understood that labeling a disk with glabel would permit the disk to
>be switched to another system and booting from that disk would not
>require other manupulations than adjusting network configuration,
>rc.conf and a few others..
>But what if there is already a disk on the system with the identical
>labels in /dev/label/ ?
>I understood that whatever the actual disk might be (ad4, ad12,
>ad1...)would be irrelevant?
>It would appear that the actual booting goes according to the label;
>if there are duplicate labels the boot will not necessarily be from the
>newly installed disk if there is another disk with duplicate glabel
>So doing a glabel seems superfluous...
>What then is the real purpose of glabel, since the boot process seems
>need a unique identifier?

Switching between machines is not what labels are for.(enlighten me if
it is)
As far as understand, it makes switching the drive in the same machine
It does not matter if labels are used, that the device is seen as
/dev/ad0 or /dev/ad{x}.
This makes adding and replacing disk much easier.
Sometimes the disk numbers change when removing raid controllers or
other hardware.


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