Re: unknown partition table starting with 2.6.28

[John Robinson <john.robinson@anonymous.org.uk>]

On 01/02/2010 20:46, Bill Davidsen wrote:
> John Robinson wrote:
>> On 15/01/2010 23:58, Timothy D. Lenz wrote:
>>> I am trying to update my kernel from 2.6.26.8 to the current .32. 
>> [...]
>>> Starting with .28 I am getting an error about unknown partition table 
>>> for all 3 md's. md0 is boot and main programs, md1 is swap, md2 is 
>>> mostly recordings storage for vdr. All 3 are raid 1 and raid is built 
>>> in.
>>
>> Your md devices aren't partitioned so you can quite safely ignore the 
>> warning. See also http://marc.info/?l=linux-raid&m=125797242110594&w=2
> 
> To clarify that a bit, the kernel can use several partition formats, and 
> something in the partitions looks like a partition table but not a 
> *valid* partition table. So the kernel warns that it doesn't recognize 
> the table.
> 
> I suspect that using a different superblock type would change (probably 
> eliminate) this, putting the md information at the start of the 
> partition, of in a bit or whatever makes the kernel happy. The kernel 
> would make us happy if it checked for a valid md superblock at the *end* 
> of the partition, but there may be reasons why that's undesirable.
> 
> Finally, I'm less willing than John to say you can ignore it, any time 
> something comes close enough to working (in an undesired way) to 
> generate an error message, if there's a simple way to be sure the kernel 
> doesn't try to use random data as a partition table, you might well want 
> to take a step to prevent a problem now.
> 
> I believe it arises out of all arrays being partitionable recently, 
> again the details don't come to mid, I've been pretty head down on 
> another project since November.

I don't think this analysis is correct. Yes, the situation has arisen 
out of all arrays - in fact all block devices - being partitionable, but 
the warning's not because of something that looks like a dodgy partition 
table, it is precisely what it says, a statement that the device does 
not contain a valid partition table. I am essentially repeating the 
contents of Doug Ledford's earlier post to this list, to which I 
referred above.

Cheers,

John.