fix remote degraded gmirror

krad kraduk at
Wed Sep 30 12:40:42 UTC 2009

2009/9/30 Robin Becker <robin at>

> .........
>> a simple
>> dd if=/dev/zero of=/dev/adX bs=1M count=1
>> would fix that if nothing else
>> if there's was no existing label, there is nothing to do except gmirror
>> man
>> instructions.  Gmirror is block level mirroring which why no other steps
>> are
>> needed.
>>  well now I really need advice, the data centre guy successfully inserted
> another disk in the right place and it appears to be the same model.
> However, smartctl -a /dev/ad4 seems to show a number of errors and many of
> the indicators are prefail or old_age.
> In addition the disk doesn't have exactly the same length so when I tried
> to insert gmirror complains that it is too small.
> What are my options?
> --
> Robin Becker
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1st thing sure up what you have.

create another mirror, partition, newfs it up and rsync the the contents of
the active drive over to it.

Keep the rsync every 10 minutes or so depeneding on how much data you have
and what impact it has on system resources

You then have two options

boot off the new drive, destroy the gmirror on the old drive and add it to
the new mirror on the old drive


buy another new drive, Make sure its bigger this time. Add it to the box and
add it the the old gmirror

you can then leave the 1st new drive in there potentially and have it as a
hot back

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