gmirror gm0 destroyed on shutdown; GPT corrupt

Marcel Moolenaar xcllnt at
Thu Jun 25 17:41:40 UTC 2009

On Jun 25, 2009, at 4:02 AM, Anton Shterenlikht wrote:
> dev_taste(DEV,mirror/gm0)
> g_part_taste(PART,mirror/gm0)
> GEOM: mirror/gm0: the secondary GPT table is corrupt or invalid.
> GEOM: mirror/gm0: using the primary only -- recovery suggested.
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

You created the mirror after the GPT, which means you destroyed
the GPT backup header. gmirror uses the last sector on the disk
for metadata and that by itself is a cause for various problems.

It's better to use gmirror per partition.

> #echo 'geom_mirror_load="YES"' >> /boot/loader.conf

Is /boot a symlink for /efi/boot?

> GEOM_MIRROR: Device gm0 destroyed.
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

This is normal.

> And when the system is rebooted, there is no /dev/mirror anymore.

You could run into a race condition between GPT and gmirror and
GPT winning (again the result of gmirror using the last sector
on a disk for metadata).

Alternatively, make sure gmirror got loaded at boot.


Marcel Moolenaar
xcllnt at

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