vinum revive does not rebuild parity (was vinum rebuildparity, when?)

Stijn Hoop stijn at
Tue Sep 7 21:52:29 PDT 2004

On Wed, Sep 08, 2004 at 11:28:46AM +0930, Greg 'groggy' Lehey wrote:
> >> [...] the parity surely is not correctly recalculated during
> >> the revive.
> If that were the case, the parity would be incorrect at offset 0.
> Yes, it is recalculated.

Of course -- I hadn't thought of that.

> >> Greg, can you tell me if this is correct behaviour?
> Sorry for the slow response.  I was at a conference last week.  No,
> it's not correct.

No problem; this is still a volunteer project last time I checked.
In a way I am glad to hear that it is not correct.

> > While not having heard back yet, I had to rebuild another subdisk,
> > but I decided to do it off-line this time. Turns out the parity was
> > rebuilt ok. 
> Yes, this is what I recommended.


> > Might there be a bug in the online rebuild code?
> Looks like it.
> The current version of Vinum is on its last legs.  Lukas Ertl is
> rewriting it, so don't expect much change in this version.  For the
> time being, just accept that you should umount before rebuilding a
> plex.

I will; it's just that somehow I was led to believe that I didn't need
to do that. This has caused me some pain in the past.

May I suggest applying the attached patch to /usr/src/sbin/vinum/vinum.8?
At least it would prevent someone else from making the same mistakes as

Thanks for your response,


The problem is that there are several people in design positions now who
couldn't design the Next Big Thing(TM) unless it involved them taking a
photocopier and someone else's design of The Next Big Thing(TM).
		-- 'Alkaiser' in a post on Slashdot on game originality
-------------- next part --------------
--- vinum.8.orig	Wed Sep  8 06:47:46 2004
+++ vinum.8	Wed Sep  8 06:51:19 2004
@@ -441,6 +441,10 @@
 .Ic checkparity
 prints a running progress report.
+It is advisable to always check the parity of a RAID-4 or RAID-5 plex after
+an unclean shutdown. Corrupt parity is as bad as degraded mode for such a
+plex; if one of the subdisks of such a plex fails, data corruption will occur.
 .It Xo
 .Ic concat
 .Op Fl f
@@ -1046,6 +1050,11 @@
 flag is specified,
 .Ic rebuildparity
 prints a running progress report.
+At present, a bug prevents rebuildparity from correctly completing its job
+when the vinum volume is mounted and being accessed. You should only rebuild
+the parity of plexes on unmounted volumes in order to guarantee correct parity
 .It Xo
 .Ic rename
-------------- next part --------------
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