[gentoo-user] cannot open root device "sda3"

[gentoo-user] cannot open root device "sda3"

[Valmor de Almeida]

Hello,

I am trying to boot gentoo from an external USB HDD.  I am getting the
error message:

  VFS: Cannot open root device "sda3" or unknown-block(2,0)
  Please append a correct "root=" boot option; here are the available
partitions:
  Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(2,0)

I am assuming that the device will be named /dev/sda since there is no
other HDD on the system. The message above does not list any available
partitions.
Any thoughts?

Here is the info from fdisk on this drive (it is a new 4096-byte sector drive):

  Disk /dev/sdb: 240.1 GB, 240057409536
  255 heads, 63 sectors/track, 29185 cylinders
  Units = cylinders of 16065 * 512 = 8225280 bytes
  Disk identifier: 0x0c7786a9

  Device       Boot     Start     End        Blocks       Id  System
  /dev/sdb1     *              1       26        208813+    83  Linux
  /dev/sdb2                   27     158      1060290      82  Linux
swap / Solaris
  /dev/sdb3                 159    2117    15735667+    83  Linux
  /dev/sdb4                2118  29185  217423710      8e Linux LVM

Thanks,

--
Valmor

Re: [gentoo-user] cannot open root device "sda3"

[Dirk Heinrichs]

Am Donnerstag 21 Januar 2010 19:08:53 schrieb Valmor de Almeida:

> I am trying to boot gentoo from an external USB HDD.  I am getting the
> error message:
> 
>   VFS: Cannot open root device "sda3" or unknown-block(2,0)
>   Please append a correct "root=" boot option; here are the available
> partitions:
>   Kernel panic - not syncing: VFS: Unable to mount root fs on
>  unknown-block(2,0)

USB storage driver in the kernel? If not, compile it in, together with 
everything needed for USB. SCSI disk driver should also be compiled in.

If yes, lookup the list archive a couple of weeks back, somebody mentioned a 
boot option to delay booting to give the kernel some time to discover USB 
devices.

HTH...

	Dirk

Re: [gentoo-user] cannot open root device "sda3"

[Valmor de Almeida]

Dirk Heinrichs wrote:
> Am Donnerstag 21 Januar 2010 19:08:53 schrieb Valmor de Almeida:
[snip]
> If yes, lookup the list archive a couple of weeks back, somebody mentioned a 
> boot option to delay booting to give the kernel some time to discover USB 
> devices.
> 
> HTH...
> 
> 	Dirk

Yup, rootdelay=5 boot option did the trick.

Thanks,

--
Valmor

Re: [gentoo-user] cannot open root device "sda3"

[Alan McKinnon]

On Thursday 21 January 2010 20:08:53 Valmor de Almeida wrote:
> Hello,
> 
> I am trying to boot gentoo from an external USB HDD.  I am getting the
> error message:
> 
>   VFS: Cannot open root device "sda3" or unknown-block(2,0)
>   Please append a correct "root=" boot option; here are the available
> partitions:
>   Kernel panic - not syncing: VFS: Unable to mount root fs on
>  unknown-block(2,0)

This almost always means that you don't have a required module compiled into 
the kernel and are not using an initrd.

Common modules are the motherboard chipset and the fs on the disk


> 
> I am assuming that the device will be named /dev/sda since there is no
> other HDD on the system. The message above does not list any available
> partitions.
> Any thoughts?
> 
> Here is the info from fdisk on this drive (it is a new 4096-byte sector
>  drive):
> 
>   Disk /dev/sdb: 240.1 GB, 240057409536
>   255 heads, 63 sectors/track, 29185 cylinders
>   Units = cylinders of 16065 * 512 = 8225280 bytes
>   Disk identifier: 0x0c7786a9
> 
>   Device       Boot     Start     End        Blocks       Id  System
>   /dev/sdb1     *              1       26        208813+    83  Linux
>   /dev/sdb2                   27     158      1060290      82  Linux
> swap / Solaris
>   /dev/sdb3                 159    2117    15735667+    83  Linux
>   /dev/sdb4                2118  29185  217423710      8e Linux LVM
> 
> Thanks,
> 
> --
> Valmor
> 

-- 
alan dot mckinnon at gmail dot com