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Old 06-24-2008, 08:17 AM   #1
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Registered: Jun 2008
Distribution: Fedora, OpenSolaris
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Question How/where are disk device mappings stored

I've tried this question once before under a Fedora specific section and got no responses, so I thought I might try a more general venue. Every time I try to install FC8 or FC9, the disk partitioning screens show a device labeled as mapper/sil_ahadcdcdbifh. This device is obviously the combination to two of my 320Gb drives given the over 600Gb size reported. I've installed to one of the other drives to see what I could do to remove this device mapping once I have FC up and running. I want to setup software raid in FC to do raid5 across three drives while leaving one for the OS and any software I install.

The motherboard is an AbitIP35pro with the ICH9R controller set to AHCI (not raid).

I've discovered that dmsetup will display the status for the mapped device:
dmsetup status -v /dev/mapper/sil_ahadcdcdbifh
Name: sil_ahadcdcdbifh
Tables present: LIVE
Open count: 0
Event number: 0
Major, minor: 253, 0
Number of targets: 1

If I run dmsetup remove /dev/mapper/sil_ahadcdcdbifh the mapping appears to go away...until I reboot. Does dmsetup not actually write to the disk, or are device mapping created from data I do not seem to be able to update (or remove)? Are device mappings created dynamically on boot?

I've tried going into the BIOS enabling raid, creating various RAID configurations and saving it, then rebooting and going back into the BIOS configuration and changing the controller back to ACHI after removing the RAID volumes. No joy. This device mapping keeps coming back. I even installed Windows and Ubuntu on the drives which did not see this device mapping, and then ran BootIt NG to remove all partitions from all drives. The mapping persists and if I cannot figure out how to remove it, I may just have it engraved on my tombstone.

Can someone, anyone point me in the right direction?
Old 07-07-2008, 03:14 PM   #2
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If you run dmraid you can use the -E setting to erase RAID metadata. I'd be more specific, but I'm stuck on a Windows machine right now. Install dmraid and type man dmraid and it'll give you the options...
Old 09-03-2008, 07:59 AM   #3
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Registered: Jun 2008
Distribution: Fedora, OpenSolaris
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Used -nodmraid option to launch install

Someone in another forum pointed me in the right direction. I used the -nodmraid option when booting into the installer. This allowed the installation to ignore the information already on the disks and create a new software raid config.

Of course then VMWare released ESXi and I wiped the machine and installed that instead.


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