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

[ramakanth varala]

Hi Pascal..

yes its RW ...

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            2610        2610        8032+  83  Linux

address@hidden ~]# ls -ltr /dev/nbd0*
brw-r----- 1 root disk 43, 0 Dec  4 11:06 /dev/nbd0

address@hidden ~]# mount /dev/nbd0p1 /home/test/test.3.5.1b.debug/mnt/boot/
mount: special device /dev/nbd0p1 does not exist

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
 253     2     104391 dm-2
 253     3   20860402 dm-3


--Not sure..what's missing..

Thanks
Rama Kanth

On Tue, Dec 4, 2018 at 3:07 PM Pascal <address@hidden> wrote:

> hi,
>
> you left fdisk without saving the changes (w before q), so there can't be
> two partitions.
> on the other hand, we should find the existing partition...
> there is a strange warning when fdisk starts: what is on the over side of
> nbd0 ?
> is /dev/nbd0 rw ?
> if you can't re-read the partitions table, can you disconnect /dev/nbd0 and
> then reconnect it ?
>
>
> Le lun. 3 déc. 2018 à 16:17, ramakanth varala <address@hidden>
> a écrit :
>
> > 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
> >> >> >
> >> >> >
> >> >> >
> >> >>
> >> >
> >>
> >
>