[gPXE] Change drive number of the iscsi boot drive?

[Andrew Bobulsky]

*"deployment occurs from an iSCSI Windows image, which currently changes the
numbering of the internal hard drives and this causes the captured images to
be deployed to the wrong drives."*

Oh hrm... you may want to read the Technet post I linked in the previous
email.  I tried to do *precisely *that and it didn't work because Windows
Setup won't image a drive that doesn't have an ARC path.  I thought I'd get
sneaky and wrote a patch to gPXE to allow booting from SAN without writing
an iBFT (to prevent WinPE from *ever* seeing the iSCSI device), but the INT
13 hook still messed up my ARC paths.

Curiously, if you're not deploying a custom Windows Setup but are instead
doing imaging directly via ImageX or some other tool, you could likely get
away with it quite easily.  /Perhaps/ you could try a build of gPXE that
prevents iBFT creation, and get away with not having an ARC path on the
disk, as your imaging utility shouldn't care.  However, you might also have
better luck with ARC paths on your system in general than I did... maybe an
INT 13 hook won't mess them up.

Regards,
Andrew Bobulsky

On Tue, Jan 18, 2011 at 12:33 PM, Binh Thai <bthai at ncst.com> wrote:

> “So having said that, I'd like to ask: _why_ do you want the drive numbers
> numbered in this way?”
>
> è I have some unattended programs that capture and deploy OS images. The
> user may boot a system from a CDROM/USB Drive and do the capturing.
> Meanwhile, the deployment occurs from an iSCSI Windows image, which
> currently changes the numbering of the internal hard drives and this causes
> the captured images to be deployed to the wrong drives. I can make the
> deployment program aware of the iSCSI drive but I’m looking for a more
> thorough solution.
>
>
>
> Could you please explain for me the relationship between gPXE iSCSI boot
> and Windows iSCSI Initiator? When does gPXE end and Windows iSCSI Initiator
> pick up?
>
>
>
> Thanks
>
> *Binh Kien Thai*
>
>
>
> *From:* Shao Miller [mailto:Shao.Miller at yrdsb.edu.on.ca]
> *Sent:* Tuesday, January 18, 2011 12:00 PM
>
> *To:* Binh Thai
> *Cc:* gpxe at etherboot.org
> *Subject:* [SPAM] - Re: [gPXE] Change drive number of the iscsi boot
> drive? - Email found in subject
>
>
>
> On 1/18/2011 11:42, Binh Thai wrote:
>
> Hi Shao,
>
> Thanks for your reply.
>
> I forgot to mention that I meant “drive 0” in the context of Windows disk
> drive numbering.
>
>
> Oh, ok.
>
>
> My goal is to boot a system from an iscsi target without disrupting the
> disk drive numbers of the internal hard drives. For example, if I have one
> internal hard drive, I want to see it detected as Disk 0 whether I boot from
> it or from the iscsi target. If I boot from the iSCSI target, I want to see
> the iscsi target as drive 1, not 0. Currently, the iSCSI drive would become
> Disk 0 and push the internal drive to Disk 1.
>
> I think the PnP enumeration process in Windows has some relationship with
> the BIOS drive numbering. Could you please point me to some in-depth
> documentation regarding the BIOS drive numbering and how int13 is used?
>
>
> I do not believe that BIOS drive numbers and Windows drive numbers have any
> correlation.  Use Microsoft's SysInternals' LoadOrd.exe to check your driver
> load order.  If you ensure that the drivers responsible for the internal
> storage adapters are loaded before the iSCSI driver, then I think your odds
> are better for the iSCSI HDD getting a higher number than the internal
> HDD(s).
>
> However, it might be the case that the startup protocol hands an MBR
> signature from boot-up to the drive number assignment routine; in this case,
> whatever drive is used for booting (your iSCSI HDD) will be drive 0 no
> matter what.  You can use Microsoft's SysInternals' WinObj.exe to check the
> mapping of the ARC names (\ArcName\) to the drive numbers
> (\Device\HarddiskX).
>
> I can only think of a convoluted way to push the boot drive up and away
> from Windows drive number 0:
> - Boot the iSCSI drive
> - Have GRUB4DOS on the drive
> - Have GRUB4DOS remap the drive number from 0x80 to 0x81
> - Chain-load the Windows boot-loader
> - Have BOOT.INI/BCD attempt to boot multi(0)disk(0)rdisk(1)partition(1)
> instead of rdisk(0) (0x81 instead of 0x80)
> - If the iSCSI drive is \Device\Harddisk1 then hopefully Windows would also
> further connect it as multi(0)disk(0)rdisk(1).  ARC _and_ HDD numbers would
> then be 1 instead of 0.  (Untested.)
>
> So having said that, I'd like to ask: _why_ do you want the drive numbers
> numbered in this way?
>
> - Shao Miller
>
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