Re: MD array keeps resyncing after rebooting

[Martin Wilck <mwilck@arcor.de>]

On 08/02/2013 02:46 PM, Francis Moreau wrote:

> Please tell me if you can find something suspicous.

One thing that I can see is that your BIOS seems to use the same time
stamp everywhere. It is clear from the dump that the BIOS has changed
the timestamp in the VD GUID, too. The timestamp used in the
"before-bios" data is 2013-08-02 08:21:10, the timestamp after is
2013-08-02 14:27:27. Wonder if that fits?

The spec says that the VD GUID consists of the vendor ID ("LSI     " in
your case), controller type (the controller's PCI ID,
8086:1d60:0000:0000), the 4-byte time stamp, and a "random number"
(0000 1450). Strangely, I also have an LSI fake RAID and it uses the
same random number. It even generated the same number through several
RAID creations. Seems to be a truly strange random number generator :-)

All in all, this makes your controller's RAID GUIDs very predictable.
But they change whenever the timestamp changes. It also explains why
this controller can't have more than a single array.

But that's not what you wanted to know, right? Besides the time stamp,
sequence number, and CRC32, there is actually no difference between the
two dumps. The suspicious part is here, same in both dumps:

00000860  00 00 ff ff ff ff ff ff  ff ff ff ff ff ff ff ff

The first two bytes in thus line are the state and init state, and the
meaning is "Optimal, consistent, *not initialized*".
And this is before *and* after BIOS started. Suspiciously, this doesn't
match what you wrote before:

> I checked during the shudown process that the array is correctly
> > stopped since at that point I got:
> >
> > # mdadm -E /dev/sda | egrep "state"
> >         state[0] : Optimal, Consistent
> >    init state[0] : Fully Initialised

This would correspond to "00 02", and it's what we should see after
initialization. On my system the BIOS sets "00 01" (Optimal, consistent,
Quick Init in progress) when it first creates an array, because the BIOS
doesn't do a full initialization. But "not initialized" is weird. The
mdadm DDF code won't set this by itself, AFAIK. Please make sure again
that the "before" data matches what mdadm/mdmon wrote just after
stopping during shutdown.

Regards
Martin