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

[Pascal]

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
>> >> >
>> >> >
>> >> >
>> >>
>> >
>>
>