Re: [Qemu-discuss] Issue related to mounting /dev/nbd0p1

[ramakanth varala]

Hi ,

I tried below steps .. still with some errors..


address@hidden ~]# fdisk /dev/nbd0

The number of cylinders for this disk is set to 2610.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
   (e.g., DOS FDISK, OS/2 FDISK)

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
Partition 1 is already defined.  Delete it before re-adding it.

Command (m for help): d
Partition number (1-4): 1

Command (m for help): d
Selected partition 2

Command (m for help): p

Disk /dev/nbd0: 21.4 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

     Device Boot      Start         End      Blocks   Id  System

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-2610, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-2610, default 2610): 4

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 2
First cylinder (5-2610, default 5):
Using default value 5
Last cylinder or +size or +sizeM or +sizeK (5-2610, default 2610):
Using default value 2610

Command (m for help): p

Disk /dev/nbd0: 21.4 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

     Device Boot      Start         End      Blocks   Id  System
/dev/nbd0p1               1           4       32098+  83  Linux
/dev/nbd0p2               5        2610    20932695   83  Linux

Command (m for help): q

address@hidden ~]# blockdev --rereadpt /dev/nbd0
BLKRRPART: Invalid argument
address@hidden ~]# ls /dev/nbd0
/dev/nbd0
address@hidden ~]# ls /dev/nbd0*
/dev/nbd0



Thanks
Rama Kanth

On Fri, Nov 30, 2018 at 6:48 PM Pascal <address@hidden> wrote:

> do not create nodes manually but with fdisk on nbd0 :
>
> # fdisk /dev/nbd0
> ## now create your partitions in fdisk
> ## use w to write changes and q to quit fdisk
>
> # blocdev --rereadpt /dev/nbd0
>
> # ls /dev/nbd0*
> ## you will now have /dev/nbd0, /dev/nbd0p1 and /dev/nbd0p2
>
> if this is not the case while the fdisk command ended without error :
>
> # sync
> # qemu-nbd -d /dev/nbd0
> # qemu-nbd -c /dev/nbd0 /the/target
>
>
> Le ven. 30 nov. 2018 à 14:04, ramakanth varala <address@hidden
> >
> a écrit :
>
> > Hi Pascal & Jakob,
> >
> > I started from first .
> >
> > I created manully the partitions as below
> >
> >    27  mknod /dev/nbd0p1 b 1 4
> >    28  mknod /dev/nbd0p2 b 1 4
> >
> > still in /proc/partitions i don't see any info , it shows as below
> >
> > address@hidden ~]# cat /proc/partitions
> > major minor  #blocks  name
> >
> >    8     0   62914560 sda
> >    8     1     104391 sda1
> >    8     2   62806117 sda2
> >  253     0   56655872 dm-0
> >  253     1    6127616 dm-1
> >
> > address@hidden ~]# fdisk  -l /dev/nbd0
> >
> > Disk /dev/nbd0: 21.4 GB, 21474836480 bytes
> > 255 heads, 63 sectors/track, 2610 cylinders
> > Units = cylinders of 16065 * 512 = 8225280 bytes
> >
> >      Device Boot      Start         End      Blocks   Id  System
> > /dev/nbd0p1   *           1          13      104391   83  Linux
> > /dev/nbd0p2              14        2610    20860402+  8e  Linux LVM
> >
> >
> > when i try for mount , i see below error
> >
> >
> > address@hidden ~]# mount /dev/nbd0p1
> > /home/test/test.3.5.1b.debug/mnt/boot
> > mount: you must specify the filesystem type
> >
> > i tried to give file system type as below, still issues.
> >
> > address@hidden ~]# mount -t ext3 /dev/nbd0p1
> > /home/test/test.3.5.1b.debug/mnt/boot
> > mount: wrong fs type, bad option, bad superblock on /dev/nbd0p1,
> >        missing codepage or other error
> >        In some cases useful info is found in syslog - try
> >        dmesg | tail  or so
> >
> >
> > Any inputs would be really helpfull..
> >
> >
> > Thanks
> > Rama Kanth
> >
> > On Fri, Nov 30, 2018 at 1:50 PM Pascal <address@hidden> wrote:
> >
> >> restart from zero if possible...
> >>
> >> # qemu-nbd -d /dev/nbd0
> >> # modprobe -rv nbd
> >>
> >> # modprobe nbd
> >> # qemu-nbd -c /dev/nbd0 /the/file
> >> # blockdev --rereadpt /dev/nbd0
> >> # fdisk -l /dev/nbd0
> >> # mount /dev/nbd0p1 /mount/point
> >>
> >> Le jeu. 29 nov. 2018 à 17:32, Jakob Bohm <address@hidden> a
> >> écrit :
> >>
> >> > Check
> >> >
> >> >     cat /proc/partitions
> >> >
> >> > If the partitions are not listed there, the kernel does not
> >> > recognize them, perhaps the kernel doesn't recognize that
> >> > nbd0 is a "partitionable disk", and thus does not create the
> >> > internal nbd0p1 and ndb0p2 devices.
> >> >
> >> > If the partitions are listed there, you just need to create the
> >> > actual /dev/nbd0p1 and /dev/nbd0p2 file names with mknod or
> >> > figure out why your "/dev/" management software (maybe udev,
> >> > maybe something better) doesn't do that for you.
> >> >
> >> > On 29/11/2018 12:46, ramakanth varala wrote:
> >> > > Still with some errors..
> >> > >
> >> > > address@hidden ~]# kpartx -a /dev/nbd0
> >> > > read error, sector 0
> >> > > read error, sector 1
> >> > > read error, sector 29
> >> > > address@hidden ~]# ls /dev/nbd
> >> > > nbd0   nbd1   nbd10  nbd11  nbd12  nbd13  nbd14  nbd15  nbd2   nbd3
> >> >  nbd4
> >> > >   nbd5   nbd6   nbd7   nbd8   nbd9
> >> > >
> >> > >
> >> > >
> >> > > On Thu, Nov 29, 2018 at 4:22 PM Nerijus Baliūnas <
> >> > > address@hidden> wrote:
> >> > >
> >> > >> Please try kpartx -a /dev/nbd0
> >> > >>
> >> > >> 2018-11-29 12:38, ramakanth varala rašė:
> >> > >>> thanks for the reply ..
> >> > >>>
> >> > >>> But i get below error when i do ..
> >> > >>>
> >> > >>>
> >> > >>> address@hidden ~]# partx -a /dev/nbd0
> >> > >>> HDIO_GETGEO: Inappropriate ioctl for device
> >> > >>>
> >> > >>> On Thu, Nov 29, 2018 at 4:04 PM Nerijus Baliūnas <
> >> > >>> address@hidden> wrote:
> >> > >>>
> >> > >>>> 2018-11-29 12:10, ramakanth varala rašė:
> >> > >>>>> address@hidden ~]# mount /dev/nbd0p1
> >> /home/test.1.3.debug/mnt/boot
> >> > >>>>> mount: special device /dev/nbd0p1 does not exist
> >> > >>>> partx -a /dev/nbd0
> >> > >>>>
> >> >
> >> >
> >> > Enjoy
> >> >
> >> > Jakob
> >> > --
> >> > Jakob Bohm, CIO, Partner, WiseMo A/S.  https://www.wisemo.com
> >> > Transformervej 29, 2860 Søborg, Denmark.  Direct +45 31 13 16 10
> >> > This public discussion message is non-binding and may contain errors.
> >> > WiseMo - Remote Service Management for PCs, Phones and Embedded
> >> >
> >> >
> >> >
> >>
> >
>