Strange, undeletable software raid partitions...

[^rooker]

I'm about to setup a new and shiny Debian Squeeze on a new and shiny computer.
So far so good, but the drives have previously been assigned as RAID 1 and used in a Windows system - and although it actually had been a hardware based RAID, the Debian installer shows me partitions marked as SoftRAID.

There are two 1.0 TB SAMSUNG HD103SJ disks in that system, and the Debian setup partitioner displays their content as follows:

Code: Select all

RAIDmd124 device #:RAIDactive #(read-only)RAIDraid1 device #sdb[0] RAID124 devi
     #1     1.0 TB
              512 B unusable
RAIDmd126 device #:RAIDactive #(read-only)RAIDraid1 device #sdb[0] RAID126 devi
     #1     1.0 TB
              512 B unusable
SCSI3 (0,0,0)  (sda) - 1.0 TB ATA SAMSUNG HD103SJ
SCSI4 (0,0,0)  (sdb) - 1.0 TB ATA SAMSUNG HD103SJ

When I select the one of the drives directly, i get the following message:

Code: Select all

You have selected an entire device to partition. If you proceed with creating a new partition table on the device, then all current partitions will be removed.
[...]
Create new empty partition table on this device?
Yes | No

Of course I choose "Yes" - and then get the following message:

Code: Select all

The selected device contains partitions used for software RAID devices. The following devices and partitions are about to be removed:

Software RAID devices about to be removed: md127 (container)

Partitions used by these RAID devices:

Note that this will also permanently erase any data currently on the software RAID devices.

Remove existing software RAID partitions?
Yes | No

Again, I choose "Yes".
So far so good, but nothing happens. It seems impossible to delete those Software RAID partitions here.

Thanks to the greatness of GNU/Linux based installers, I pressed "Alt+F2" and opened another shell - and started "fdisk".
Puzzling, but fdisk says there is *nothing* on those disks. NOTHING! No leftovers, no software RAID whatsoever - nothing. WTF?

Luckily, this computer has the exact same mainboard as the computer those drives have previously been used with. I'll try to set the SATA mode in BIOS to "RAID" (instead of IDE, as it is know) and try to use to RAID BIOS to remove those leftovers... Wish me luck!

EDIT: Yesssss! it worked exactly as planned. See replies below for details.

[^rooker]

by the way: I've already had funny adventures with that mainboard and its pseudo RAID handling:
Debian Lenny on Intel DH57JG mainboard

And here are some links related to this issue:

• Debian auf Intel Software RAID installieren
• Bug report: Installing Squeeze on a Intel Matrix BIOS RAID1 volume
• DMRAID

As far as I would say, that's not really Debian's fault that it can't properly handle this situation. Yes, it would be nice, but: It's generally a strange thing that that Intel RAID "acts" like a hardware RAID, but is in fact some strange "configure me like a hardware raid, but I'm actually my own strange software raid"-thing.

In that case, it's actually absolutely better to use GNU/Linux's softraid capabilities instead, since they're well documented, portable and administrable

[^rooker]

I've now done the following:

• In the BIOS, changed the "Chipset-SATA Mode" to "RAID" (was IDE):
  Configuration > SATA Drives > Chipset-SATA Mode
• Rebooted the machine, and then entered the RAID controller's BIOS by pressing "Ctrl+I" - (aka "Intel(R)
• Matrix Storage Manager option ROM v8.9.0.1023 PCH-D")
• Both disks show up yellow, marked as "Degraded"
• In the RAID controller's BIOSwRAID5"), choose "Reset Disks to Non-RAID"
• Now both disks show up in green as "Non-RAID Disk"
• Then reboot, enter the system BIOS and change the Chipset-SATA Mode back to "IDE"

...and then back to the Debian Squeeze installer!