Unexpected gmirror behavior: Is this a bug?

Peter Steele psteele at maxiscale.com
Fri Apr 24 20:52:35 UTC 2009


> This definitely looks like a bug. Try asking again on the freebsd-geom@ 
> list. Provide output of "gmirror list". 

I'll try that list... 

>So, your steps were: 

>1. ad4, ad6, ad8 and ad10 in a 4-way mirror 
>2. ad4 fails. At this point did you do a "gmirror list"? I.e. did 
>gmirror detect it failing? If I read it correctly, the GenID field 
>should have been increased in this case. 
>3. The system continues to be used 
>4. You power it down, take out and reinsert ad4 
>5. On boot, ad4 is detected, inserted in the mirror but as a "known 
>good" copy, not a stale one. 
> 
>Correct? 

Yes, that's basically the sequence that occurred. I can easily recreate the condition though. I shut my box down, took out ad4 and then rebooted. The system complained about ad4 being missing and proceeded with a mirror using 3/4 of the drives. I then created a file on the system, shutdown again, and then reinserted ad4. On reboot as the system was starting up the gmirror driver, it detected ad4 but instead of reinserting in in the most recent mirror made up of the other drives, it became the active drive and kicked out its old partners, When the old drives were reinserted manually into that mirror they were of course synced with the data from ad4, destroying their more recent data. 

This does not happen if I do the same thing with a drive other than ad4. 

>What version of FreeBSD are you using? 

7.0-p10 or so. 



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