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Re: Problems probing a LVM device with GRUB2



Hello Tom, thanks again for your assistance

Tom H writes:

> On Fri, Sep 17, 2010 at 8:01 AM, Alberto Luaces wrote:
>> Tom H writes:
>>> On Thu, Sep 16, 2010 at 6:02 AM, Alberto Luaces wrote:

[...]

> Since grub-probe isn't detecting your lvm setup, it's normal for
> grub.cfg not to have "insmod lvm".
>
> I don't think that adding that adding that line to
> "/boot/grub/device.map" could be that useful and I'm not sure that
> whether adding "--modules=..." is additive or not because you need a
> few more modules to be able to boot. I've forgotten the command to
> list the core.img modules but I'll try to find it and list the default
> ones that you'd have to add to your command if it isn't additive.
>

Certainly it could be useful to know the list of modules contained in a
specific core.img. Speaking of which, when I boot from /dev/sdb an get
the error about not findind a partition with the uuid, I can type
without any error

insmod lvm
insmod ext2

but then, if I type `ls', only the normal partitions are listed
(hd*,msdos*), and none of the LVM volumes. Here hd0 == sdb and hd1 ==
sda.

>
> What is and what's on sda?
>

Currently I have my system in /dev/sda. I am in the process of moving it
to a second hard drive, /dev/sdb. Using the GRUB on /dev/sda I can boot
into the LVM root partition and try to install GRUB on /dev/sdb, in
order to get rid of the /dev/sda disk eventually. After the copy process
of the ext partitions, I generated new UUIDs for the new ones in order
to avoid clashes.

>
> More data requests...
>
> What is the output of:
>
> pvs
> lvs
> vgs
> fdisk -l /dev/sdb
> grub-probe --target=drive -d /dev/sdb
> grub-probe --target=drive -d /dev/sdbX
> grub-probe --target=drive -d /dev/dm-0
> grub-probe --target=drive -d /dev/mapper/lvm_volume-debian_root
> (the last one with your extra line and with it commented out)
>

Ok, here it is. I collected that data from the system in the LVM,
booting manually from GRUB:

pvs
  PV         VG         Fmt  Attr PSize  PFree
  /dev/sdb2  lvm_volume lvm2 a-   77,19g    0 

lvs
  LV          VG         Attr   LSize  Origin Snap%  Move Log Copy%  Convert
  debian_root lvm_volume -wi-ao 76,00g                                      
  swap        lvm_volume -wi-a-  1,19g                                      

vgs
  VG         #PV #LV #SN Attr   VSize  VFree
  lvm_volume   1   2   0 wz--n- 77,19g    0 

fdisk -l /dev/sdb
GNU Fdisk 1.2.4

[...]

Disk /dev/sdb: 250 GB, 250056737280 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System 
/dev/sdb1               1       20325   163260531    7  HPFS/NTFS

/dev/sdb2           20325       30402    80943502   8e  Linux LVM

grub-probe --target=drive -d /dev/sdb
(/dev/sdb)

grub-probe --target=drive -d /dev/sdb1
(/dev/sdb,msdos1)

grub-probe --target=drive -d /dev/sdb2
(/dev/sdb,msdos1)

grub-probe --target=drive -d /dev/dm-0
(lvm_volume-debian_root)

grub-probe --target=drive -d /dev/mapper/lvm_volume-debian_root
(lvm_volume-debian_root)

If I delete the line in device.map, the only output that change is:

grub-probe --target=drive -d /dev/dm-0
(/dev/dm-0)

Regards,

-- 
Alberto


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