Re: Periodic RebuildStarted event

[NeilBrown <neilb@suse.de>]

On Tue, 15 Mar 2011 07:21:09 +0300 CoolCold <coolthecold@gmail.com> wrote:

> On Tue, Mar 15, 2011 at 6:41 AM, NeilBrown <neilb@suse.de> wrote:
> > On Tue, 15 Mar 2011 06:16:22 +0300 CoolCold <coolthecold@gmail.com> wrote:
> >
> >> Hello!
> >>
> >> On Tue, Feb 8, 2011 at 3:25 AM, NeilBrown <neilb@suse.de> wrote:
> >> [snip]
> >> > Then start either the
> >> > 'next' array at the beginning, or the 'current' array at the current point
> >> > (write to sync_min).
> >> I couldn't find documentation for sync_min/sync_max sysfs params at
> >> least for repo cloned from
> >> git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-2.6.37.y.git
> >> coolcold@coolcold:~/gits/linux-2.6.37.y$ grep -qi sync_min
> >> Documentation/md.txt || echo failed find docs
> >> failed find docs
> >
> > Yes, sorry about that.
> May be I can help and create patch for md.txt after this thread? If
> yes, it would be nice to get some link for proper patch providing
> instructions, never did patches for kernel ;)

Patches always welcome!!  So yes please.

Have a read through SubmittingPatches in linux/Documentation
(same directory that 'md.txt' is in).
That should get you close enough.

Thanks,
NeilBrown



> 
> >
> >>
> >> As I could understand from sources - resync_min & resync_max are
> >> expressed in sectors (512bytes?)  and are set to 0 & total sectors on
> >> device accordingly. resync_max value should be divisible by array
> >> chunk size (in sectors) . After setting this values, one can trugger
> >> "check" / "repair" into sync_action.
> >
> > Yes - sectors (multiples of 512 bytes)
> > Yes - 0 and a big number.  sync_max is actually set to MAX_LONG rather than
> >      the actual total number of sectors.
> >
> > Yes - one can trigger 'check' or 'repair' and it will obey these limits.
> > When it reaches 'sync_max' it will pause rather than complete.  You can
> > use 'select' or 'poll' on "sync_completed" to wait for that number to
> > reach sync_max.  Then you can either increase sync_max, or can write
> > "idle" to "sync_action".
> >
> >>
> >> My basic idea is to use this method to clear pending sectors from
> >> SMART checks and looks like this gonna work, am i right?
> >>
> >
> > I don't know exactly what "pending sectors" are, but if they are sectors
> > which return an error to READ and can be fixed by writing data to them, then
> > you are right, this should 'clear' any pending sectors.
> Yes, i meant that kind.
> >
> > Of course you will need to be careful about mapping the sector number
> > from smart to the second number given to 'sync_min'.
> I guess you meant "sector" not "second" here?
> 
> > Not only must you
> > adjust for any partition table, but also the 'data offset' of the
> > md array must be allowed for.
> So, for 0.9 metadata format offset is always gonna be 0, right?
> And if the bad thing happens - bad block with read error is found on
> metadata section, will mdadm with --update <something> will be enought
> to do force write?
> 
> >
> > NeilBrown
> >
> >
> >
> >> > Then wait for however long you want, abort the check (write 'idle' to
> >> > 'sync_action') and find out where it got up to (read sync_min) and record
> >> > that for next time.
> >> >
> >> > NeilBrown
> >> >
> >>
> >>
> >
> >
> 
> 
> 

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