Bug#422851: "grub-probe -t partmap" doesn't work with software RAID

[Robert Millan]

Hi,

I'm forwarding you a bug report from Debian.  It seems that the grub-probe
-t partmap feature I just added doesn't play nice with RAID.  Unfortunately,
I have no idea how software RAID is implemented.  Is it okay to just exit
succesfuly and install core.img without any partmap module?

On Wed, May 09, 2007 at 04:37:45PM +0100, Sam Morris wrote:
> On Wed, 2007-05-09 at 17:16 +0200, Robert Millan wrote:
> > On Wed, May 09, 2007 at 03:02:48PM +0100, Sam Morris wrote:
> > > 
> > > Yes, "grub-probe: error: Cannot detect partition map for md0". The
> > > message doesn't appear when grub-pc's postinst is run, however.

Note to GRUB maintainers: earlier this caused a segfault.  I fixed it in
CVS to print that error instead.

> > > > Also, what is the result of "parted /dev/md0 print" ?
> > > 
> > >         Disk /dev/md0: 300GB
> > >         Sector size (logical/physical): 512B/512B
> > >         Partition Table: loop
> >                            ^^^^
> > This means there's indeed no partition table, just a filesystem.
> > 
> > Did you install Debian on purpose without creating any partition table, or is
> > this just the normal result when using software RAID?  What does parted say
> > about your real disk(s)?
> 
> Interesting. This system has been installed for quite a few years; I
> moved it to raid1 by hand.
> 
> The system has several disks; md0 consists of hdb2 and hdg2. Here's what
> parted says about hdb:
> 
>         Disk /dev/hdb: 300GB
>         Sector size (logical/physical): 512B/512B
>         Partition Table: msdos
>         
>         Number  Start   End    Size   Type     File system  Flags
>          1      32.3kB  543MB  543MB  primary                    
>          2      543MB   300GB  300GB  primary  ext3         raid 
> 
> When you say there is no partition table, I guess you mean inside md0
> itself? AFAIR, the array was created before partitionable md arrays were
> added to Linux... or at least before mdadm had the option to create
> them.
> 
> I just ran this on a system that uses RAID which I created with the etch
> installer:
> 
>         Disk /dev/md8: 57.5MB
>         Sector size (logical/physical): 512B/512B
>         Partition Table: loop
>         
>         Number  Start   End     Size    File system  Flags
>          1      0.00kB  57.5MB  57.5MB  ext3              
> 
> Which appears to confirm my belief that partitionable arrays are unusual
> rather than the default.

-- 
Robert Millan

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