GREETING:
Hi, LinuxQuestions.org! Let me start by saying that you've been a useful source of information for years. Always among the top search results, this forum has participated in countless solutions. I just want to say thank you for the expertise, patience, and diversity of content! This site has gotten me out of a pickle on more than one occasion. Thanks!)
GOAL:
Trying to recover data from an ext4 partition on a disk that was previously RAID1, specifically /home, without using external storage.
PROBLEM:
I am unable to mount the intended partition.
Fdisk shows them but /dev doesn't.
Xubuntu (during installation and now) showed only 1-10GB partition as well.
BACKGROUND:
1. I'm lost. (I've worked on the issue, as time permitted, over the course of weeks (maybe months). Plus, I was half-asleep last night --and progressed to where I am now. I woke up to a working Xubuntu installation and vaguely remember inserting the cdrom. So, assume I don't recall anything more than what I've posted. If you want more information, my memory won't help. I will need to be told how to figure it out if it isn't a common command.
2. The last linux installation (which used the /home) was Bodhi linux, which I understand doesn't support RAID. (Yes, I'm confused by that.) I used the BIOS settings to configure RAID and I remember installation was bumpy (testing several bios configurations and using xubuntu to get the disk ready) but I can't account for my actions.
3. Installation of either dist has been a headache. Both insallation scripts (Bodhi & Xubuntu) reported mounted partitions when scanning the disks. Choosing the option to unmount failed in both installers, regardless of the BIOS settings.
This was apparently a working RAID1 system running Bodhi Linux a couple days ago. Originally, I believe I used mdadm on the live-Xubuntu, partitioned the drive, and then rebooted and installed Bodhi. Howeever, there were several installation attempts using various BIOS configurations. I don't know exactly what I did but trial'n'error got Bodhi running. Once I had a working Bodhi system, I do remember concluding is the fakeRAID but I didn't think Bodhi Linux supported it and don't know how to tell for certain. I thought maybe RAID support had been added in latest version. My current dilema started when I tried to re-install Bodhi again yesterday.
STATUS:
I am currently working in Xubuntu 12.04 as it was installed (in my sleep).
If I remember correctly, all RAID is disabled in the BIOS, but I still had problems during installation. Somehow I managed to screw things up so that (in the partition manager during installation, I could only see the first physical partition (10Gb) sda1 ("pdc_dhcjgfgdd1"), which is what I had been using for root. So, I installed Xubuntu's / there and decided to get SOMETHING running on the machine. Now that I've got a full linux running, I would like to figure out what I messed up, how to fix it, and understand the probem in case I use RAID again in the future.
mtab looks like RAID is being used...
Code:
/dev/mapper/pdc_dhcjgfgdd1 on / type ext4 (rw,errors=remount-ro)
...nothing else mounted (not even swap--I think I encountered a problem formatting it so I skipped swap as a temporary installation)
I am unable to 'mount -t ext4 -o force /dev/sda6 /mnt/tmp' because my /dev contains:
Code:
sda
sdb
dm-0
dm-1
mapper/pdc_dhcjgfgdd -> ../dm-0
mapper/pdc_dhcjgfgdd1 -> ../dm-1
disk/by-id/ata-LITE-ON_DVD_D_LH-16D1P -> ../../sr1
disk/by-id/ata-Maxtor_6Y080M0_Y2Q9L4QE -> ../../sdb
disk/by-id/ata-Maxtor_6Y080M0_Y2QA0AXE -> ../../sda
disk/by-id/dm-name-pdc_dhcjgfgdd -> ../../dm-0
disk/by-id/dm-name-pdc_dhcjgfgdd1 -> ../../dm-1
disk/by-id/dm-uuid-DMRAID-pdc_dhcjgfgdd -> ../../dm-0
disk/by-id/dm-uuid-part1-DMRAID-pdc_dhcjgfgdd -> ../../dm-1
disk/by-id/raid-pdc_dhcjgfgdd-part1 -> ../../dm-1
disk/by-id/scsi-SATA_Maxtor_6Y080M0_Y2Q9L4QE -> ../../sdb
disk/by-id/scsi-SATA_Maxtor_6Y080M0_Y2QA0AXE -> ../../sda
cat /proc/mdstat:
Code:
Personalities :
unused devices: <none>
When using 'mdadm --assemble' or '--build' (and in my boot log), I am getting (as error output):
Code:
device-mapper: table: 252:2: linear: dm-linear: Device Lookup Failed
three times.
'fdisk -l sda/sdb':
Code:
Disk /dev/sda: 82.0 GB, 81964302336 bytes
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 19531775 9764864 83 Linux
/dev/sda2 19533822 160086015 70276097 5 Extended
/dev/sda5 19533824 29296639 4881408 82 Linux swap / Solaris
/dev/sda6 29298688 158201855 64451584 83 Linux
/dev/sda7 158203904 160086015 941056 b W95 FAT32
Disk /dev/sdb: 82.0 GB, 81964302336 bytes
Device Boot Start End Blocks Id System
/dev/sdb1 2048 19531775 9764864 83 Linux
/dev/sdb2 19533822 158201855 69334017 5 Extended
/dev/sdb5 19533824 29296639 4881408 82 Linux swap / Solaris
/dev/sdb6 29298688 158201855 64451584 83 Linux
The data I am after is on sda6 or sdb6. I don't see a reason either wouldn't be in tact. With the exception of putting Xubuntu / on sda1, this partitioning scheme reflects the original: 10gb-root, 5gb-swap, and about 65mb /home. (sda7 is fat32 was created during installation and is empty)
PREFERRED SOLUTION:
I would like to abandon the whole RAID thing, repartition one of the drives for /, swap, /home and the other as /backup-storage. That wouldn't be a problem for me, except the whole RAID issue is complicating matters.
Before a "/backup-storage" partition can be created, I want to salvage my previous home directory. (In fact, the only data I care to salvage is either sdx6 partition. My current / (Xubuntu) is expendable. )
EXTRA CREDIT:
It is practically as important to understand the problem as it is to resolve it. I have tinkered with the BIOS and attempted installation of two or three distributions with various settings and I'm pretty frustrated. If I come out of this with a more comprehensive understand of RAID in linux, it will have been worth it. URLS for RAID quickrref or tutorials would be apprecaited too.
Its mirroring! (The nap may have helped too.) I physically disconnected the second harddrive. (warning: If it were raid0 (or striping), this would mean further complication.) With fakeraid off in bios, that left me with a much less complicated situation... a hard drive, which used to be raid, that I need the data from partition #6. 
