SCSI devices and PowerVault

J. Epperson linux-poweredge at
Thu Apr 6 08:46:52 CDT 2006

Matt should probably put this one in the FAQ.

On Mon, Jan 02, 2006 at 05:56:15PM +0000, Marc Kirchner wrote:
> Hi,
> we are currently experiencing problems with the new megaraid_mbox driver
> using a combination of
>         - Dell PowerEdge 2600, 1 cpu
>         - Dell PowerEdge Expandable RAID controller 4/Di (rev 01)
>         - Debian system (FYI)
>         - linux kernel image 2.6.14-2-686
>         - DC in RAID/SCSI mode, with
>         - an external RAID (showing up as a single big (5.2T) SCSI disk)
>           attached to the second (SCSI) channel of the internal
>           controller
>         - megaraid_mbox version
>  From what we observed, connecting the external SCSI disk changes the
> device order during startup; the external drive gets /dev/sda and the
> (logical RAID5-) drive gets /dev/sdb, which is a behaviour not exhibited
> by the old legacy megaraid driver under 2.6.11.
> It seems as if the new driver *first* finds all physical devices and
> *then* finds the logical devices for each phsical device, thus detecting
> the external SCSI disk before the internal RAID.
> Eventually, this leads to a kernel panic, as the root device gets
> shifted around to /dev/sdb where we do not expect (and do not want)
> it to be.
> For the moment we got around the assignment problem by supplying
> fast_load=1 to the megaraid_mbox module, which is no solution as it
> effectively disables the external phsical device...
> Anyone with similar experiences and/or ideas on how to tackle this problem?

This is a common issue.  Red Hat solves it by making their initial
ramdisk have support for "root=LABEL=/" syntax on the kernel command
line, which then uses file system labels (e.g. e2label) to assign
unique labels to each file system, and them does mount-by-label.  Then
you don't care what name the kernel assigns to a given disk, you only
care that the file system labels are unique across the system.

I don't know if Debian has a similar construct, but would hope so.


On Thu, April 6, 2006 04:59, Tanguy LE CARROUR wrote:
> Hi,
> I need to make a standard configuration of 5 dell PE1850 running Gentoo :
>     SCSI card :    1000:0030    "Symbios|53c1030"
>     RAID ctrl :     1000:1960     "LSI Logic|PowerEdge RAID Controller
> 3/QC"
> Two of them will be connected to a PowerVault 220s.
> Whithout PV, the internal scsi disk is /dev/sda ... but on the PE
> connected to PV ( w/ 2 logical drives configured ) I have:
>     /dev/sda   :   first LD
>     /dev/sdb   :   second LD
>     /dev/sdc   :   internal disk
> I've unsuccesfully modified the SCSI detection configuration via LSI
> bios configuration.
> Regards
> Tanguy
> PS: Is there a way to manage PowerVault Array under Gentoo ( whithout
> OpenManage ) ?
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