Frederick Bruckman writes:
> In article <20060610190920.35138325C7@cs.usask.ca>,
> 	Greg Oster <oster@cs.usask.ca> writes:
> > Mark Cullen writes:
> >> Greg Oster wrote:
> >> > Mark Cullen writes:
> >> > 
> >> >>but the data on the two disks is still 
> >> >>different, that is, /dev/wd3a still has the old copy of the data. 
> >> > 
> >> > 
> >> > Um... after the 'raidctl -i raid0' completes, the data parts of wd1a 
> >> > and wd3a had better be *exactly* the same!
> >> 
> >> They weren't the same afterwards! If I mounted just the disk that was 
> >> missing when I added the new data, after doing an -i, the data was *not* 
> >> there on that disk. I had to force a rebuild of the disk in order to get 
> >> the data on to it.
> >>
> >> However, I may know why? I took wd1 out, and put the new data on wd3. If 
> >> I issue a -i, does it use the first disk in the array config to rebuild 
> >> the parity? 
> > 
> > Yes.  The first disk in a RAID 1 set is considered the 'master', and 
> > in the face of having 2 disks where it can't tell which is "more 
> > correct", the 'master' will be used as the difinitive source.
> 
> Now, if Mark had just removed wd1, wrote some data to wd3,
> shutdown cleanly and added wd1 back, wd3 would become the
> master, right? 

Correct.

> We hope? 

Very much so :)

> It only happened the way it did because he used "raidctl -C"?

Yes.

Later...

Greg Oster