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Re: unbootable system after fresh 4.0r5 installation



Jukka Salmi --> debian-user (2008-12-07 16:27:57 +0100):
> Hello,
> 
> Sven Joachim --> debian-user (2008-12-05 17:54:56 +0100):
> > On 2008-12-05 17:27 +0100, Jukka Salmi wrote:
> > 
> > > I just installed Debian 4.0r5 on a i386 systems (Dell PowerEdge 2950).
> > > While the installer seemed to have succeeded without problems, the
> > > freshly installed system didn't boot because its root file systems could
> > > not be found:
> > >
> > > 	Begin: Waiting for root file system... ...
> > > 	[...]
> > > 	sd 3:0:0:0: Attached scsi removable disk sdb
> > >
> > > At this point the system hanged for some minutes, until
> > >
> > > 	ALERT! /dev/sdb3 does not exist. Dropping to a shell!
> > >
> > > was output and the BusyBox shell was executed.
> > >
> > > But indeed there is no /dev/sdb; there's only one (logical) disk
> > > present, /dev/sda.
> > 
> > How many physical discs does the system have (removable and
> > non-removable)?
> 
> The system has three SCSI disks, but since they are connected to a RAID
> controller to form a RAID 5 the OS should see just a single disk.
> 
> BTW, I see the same problem on another i386 system (also a PowerEdge
> 2950).  It has six SCSI disks, four of which form a RAID 1+0, and two a
> RAID 1.  The installer sees /dev/sd[abc], but after the system is
> installed the disk which was sdc became sdb, and the original sdb became
> sda.
> 
> I should probably find out what sda is...  I can try this tomorrow.

The installer kernel prints (hand-typed):

[...]
  Vendor: Dell      Model: Virtual  CDROM    Rev: 123
  Type:   CD-ROM                             ANSI SCSI revision: 00
  Vendor: Dell      Model: Virtual  Floppy   Rev: 123
  Type:   Direct-Access                      ANSI SCSI revision: 00
usb-storage: device scan complete
usb-storage: device scan complete
sr0: scsi-1 drive
sr 0:0:0:0: Attached scsi CD-ROM sr0
sr 0:0:0:0: Attached scsi generic sg0 type 5
scsi 1:0:0:0: Attached scsi generic sg1 type 0
sd 1:0:0:0: Attached scsi removable disk sda
floppy0: no floppy controllers found
[...]

Hmm, is sda this "Virtual Floppy"?  What's this?  And what's a "Virtual
CDROM"?  (There's an ATAPI CD-ROM connected to the system, but no floppy
drive.)

However, the real disk later (as soon as the installer menu "detect
disks" is selected) attaches as sdb:

[...]
scsi3 : LSI Logic SAS based MegaRAID driver
[...]
scsi 3:0:32:0: Attached scsi generic sg2 type 13
  Vendor: DELL      Model: PERC 6/i          Rev: 1.21
  Type:   Direct-Access                      ANSI SCSI revision: 05
SCSI device sdb: 570949632 512-byte hdwr sectors (292326 MB)
[...]
sd 3:2:0:0: Attached scsi disk sdb
sd 3:2:0:0: Attached scsi generic sg3 type 0
[...]

What seems to be the problem is the order in which those devices attach.
After installation and the following restart, the new kernel boots as
follows:

[...]
scsi0 : LSI Logic SAS based MegaRAID driver
[...]
  Vendor: DELL      Model: PERC 6/i          Rev: 1.21
  Type:   Direct-Access                      ANSI SCSI revision: 05
[...]
SCSI device sda: 570949632 512-byte hdwr sectors (292326 MB)
[...]
sd 0:2:0:0: Attached scsi disk sda
[...]
  Vendor: Dell      Model: Virtual  Floppy   Rev: 123 
  Type:   Direct-Access                      ANSI SCSI revision: 00
  Vendor: Dell      Model: Virtual  CDROM    Rev: 123 
  Type:   CD-ROM                             ANSI SCSI revision: 00
usb-storage: device scan complete
sd 3:0:0:0: Attached scsi removable disk sdb
usb-storage: device scan complete
sr0: scsi-1 drive
sr 2:0:0:0: Attached scsi CD-ROM sr0
scsi 0:0:32:0: Attached scsi generic sg0 type 13
sd 0:2:0:0: Attached scsi generic sg1 type 0
sr 2:0:0:0: Attached scsi generic sg2 type 5
sd 3:0:0:0: Attached scsi generic sg3 type 0
floppy0: no floppy controllers found
[...]

Hmm, this is a little bit scary because I don't understand how the
kernel choses the order of attaching devices.  Can this be made static
somehow?  I.e. can I somehow configure the kernel to always recognise
the SCSI RAID controller as scsi0?


> > the installed system?
> 
> I don't remember which version they were exactly (something like
> 2.6.18?), but calling uname(1) from an installer shell and from the
> installed system's shell both showed the same release version.

Installer kernel:
~ # uname -a
Linux (none) 2.6.18-6-486 #1 Sat Jan 26 08:50:43 UTC 2008 i686 unknown

Installed kernel:
debian:~# uname -a
Linux debian 2.6.18-6-686 #1 SMP Mon Oct 13 16:13:09 UTC 2008 i686 GNU/Linux


Regards, Jukka

-- 
bashian roulette:
$ ((RANDOM%6)) || rm -rf ~


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