burnt again by gmirror

[Eric Anderson]

On 10/31/06 14:46, Rick C. Petty wrote:
> On Tue, Oct 31, 2006 at 02:10:03PM -0600, Eric Anderson wrote:
> 
>> You probably need to do a gmirror forget, then a gmirror remove (on
>> ad8), then re-insert it.
> 
> The forget seemed to fix it.  FYI:
> 
> # gmirror remove gm0 ad8
> No such provider: ad8.
> 
> I'm not sure if that step was even necessary.  At least now both ad4 and   
> ad8 are listed and are of the same size.  I was worried gmirror would try  
> to allocate its metadata on ad8 twice.  I don't know why I thought that,   
> because gmirror would treat the ad8 as a provider and overwrite any 
> previous metadata when doing a "gmirror insert".
> 
>> gmirror probably kicked it out because of errors?
> 
> I guess that's what my question was really trying to get at.  What caused  
> the error, what was the error, and why did gmirror both not recognize ad8  
> and also think there was a missing disk.  I guess if it was expecting a    
> specific ID and ad8 no longer had that ID (it got wiped for some odd 
> reason?) it would behave as such.  That explains the last question.  The   
> first two are hard to diagnose w/o dmesg.  :(

If the disk has enough trouble, gmirror will kick it out of the mirror 
and mark it as such.  It won't re-add the disk to the mirror (it still 
thinks it's a bad drive) unless you manually force it to (which you did 
with the forget).  It wouldn't let you insert it, because it was already 
known to the mirror.

> Still, I'm curious why/how ad8's metadata could have been clobbered.
> gmirror is the only one who would write to it, the filesystem is mounted
> from gm0* -- kinda scary.  I guess the lesson here is to use simple gmirror
> configurations in case the metadata gets clobbered.


I don't think it did get clobbered.  I think things went exactly as it 
should have actually.

Eric



-- 
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Eric Anderson        Sr. Systems Administrator        Centaur Technology
Anything that works is better than anything that doesn't.
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