Re: Re: General question

"Also sprach Stephan von Krawczynski:"
> > Err - I think you are trying to dictate the direction in which resync is
> > done?
> 
> Yes, thats right.
> 
> > I'm pretty sure that everything should work right automatically.
> 
> It does not, I checked that. Basic reason is:
> 
> Jun  7 18:50:15 mail-a01 kernel: md: ndb's event counter: 00000000
> Jun  7 18:50:15 mail-a01 kernel: md: nda's event counter: 00000000

Unusual. Practically anything increments the event counter. Even
starting raid! So 0 is not a usual number to see.

> Jun  7 18:50:15 mail-a01 kernel: md: md0: raid array is not clean -- starting
> background reconstruction
> Jun  7 18:50:15 mail-a01 kernel: md: RAID level 1 does not need chunksize!
> Continuing anyway.
> Jun  7 18:50:15 mail-a01 kernel: md0: max total readahead window set to 124k
> Jun  7 18:50:15 mail-a01 kernel: md0: 1 data-disks, max readahead per
> data-disk: 124k
> Jun  7 18:50:15 mail-a01 kernel: raid1: device ndb operational as mirror 1
> Jun  7 18:50:15 mail-a01 kernel: raid1: device nda operational as mirror 0
> Jun  7 18:50:15 mail-a01 kernel: raid1: raid set md0 not clean; reconstructing
> mirrors
> Jun  7 18:50:15 mail-a01 kernel: raid1: raid set md0 active with 2 out of 2
> mirrors
> Jun  7 18:50:15 mail-a01 kernel: md: syncing RAID array md0
> 
> And after that the data I wrote raid-offline to ndb is gone....

Well, you should be able to increment the event count on ndb by doing
almost anything to it. Even removing nda from the array will increment
ndb's count! Any event of note at all will increment the count. So I
don't see how you got it to stay at zero!

> > The event count on the primary will be old, so it will be resynced from
> > the secondary when the primary is brought into the mirror.
> 
> The problem is that the event counter is obviously not updated if the fs is not
> mounted via enbd but locally.

You are saying that it is not in a raid? Even the act of removing it
from a raid should increment the count.

If you wanted, you could keep it in a trivial raid locally which would
up the count plenty.

> As seen above both counters are zero, although I
> wrote 30 M data to the partition that ndb uses.

Well, writing does not alter the count. It's array config changes that 
change the count.

Peter