External array showing as /dev/sda

J. Epperson Dell at epperson.homelinux.net
Sun Mar 21 09:48:37 CDT 2010


On Sat, March 20, 2010 17:05, David Hubbard wrote:
> From: linux-poweredge-bounces at dell.com
>>
>> Probably.  But it may not be worth it.  Why does it matter to
>> you?  Not saying that it doesn't matter, just trying to
>> understand why.   Getting it to be /dev/sda during install,
>> for instance, wouldn't guarantee that it
>> would be that when you booted the installed kernel.
>
> Because I can't figure out how to get the OS installed
> otherwise.  As it stands currently, I would like to use
> RAID 50 on both the internal and external arrays.  Dell's
> raid controllers do not allow you to create anything other
> than one logical drive presenting 100% of the physical
> raid 50 array size to the OS as a drive, so basically
> this means my external /dev/sda drive shows as 24 TB,
> my internal /dev/sdb drive shows as 4.5 TB.
>
> So, trying to install RHEL 5.4 x86_64, the LVM wizard
> cranks up and since the external array is /dev/sda
> I un-check the box to tell the installer to not look
> at that 'drive'.  I leave /dev/sdb checked which is
> my 4.5 TB internal drive.  Proceed and then the
> installer tells me my boot drive is managed by GPT
> but the system cannot boot with GPT and I'm done.
> As far as I can tell there is not currently a supported
> way to get RHEL 5 installed with the server in UEFI
> boot mode, or at least I can't figure it out, I did
> try putting it in UEFI mode but it refused to boot
> off an ISO on DVD or a native DVD.  So you can't
> boot off a GPT drive and you can't install to a
> MBR drive lol.
>
> As best I can tell, this leaves me with the only
> option being get internal to show as /dev/sda,
> waste a bunch of money by being forced to reconfigure
> that array as a RAID 1 of two drives for the sole
> purpose of being able to present a 'drive' of less
> than 2 TB to the OS so RHEL will install on it using
> MBR as /dev/sda, do the remaining six disks as RAID
> 50 and let them become /dev/sdb, keep the external
> array as RAID 50 /dev/sdc now.  I can't accomplish
> this without the internal raid controller being
> /dev/sda though so the installer will make it past the
> partitioning step.  Also quite unhappy that the two 750
> GB drives that should have been part of my RAID 50
> internal will effectively be used to store about 2 GB
> of boot and OS files but I think I'm stuck.
>

I'm somehow missing how getting the non-installable smaller GPT VD to be
/dev/sda will change that scenario. The other responder echoed one of my
initial thoughts when he suggested turning off the external array.  That
should do it.

I did run across a post over on the Centos forums where a guy said that he
got around a Centos refusal to install on GPT by dropping to an alternate
console (Ctrl-Alt-F2) and wiping the beginning of the drive with "dd
if=/dev/urandom of=/dev/sda".  Said that on reboot it didn't quibble about
the drive.  No other details; you might end up with only 2Tb usable as I
think about it.  Perhaps worth a try.



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