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!)
Trying to recover data from an ext4 partition on a disk that was previously RAID1, specifically /home, without using external storage.
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.
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.
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...
/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:
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
unused devices: <none>
When using 'mdadm --assemble' or '--build' (and in my boot log), I am getting (as error output):
device-mapper: table: 252:2: linear: dm-linear: Device Lookup Failed
'fdisk -l sda/sdb':
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)
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. )
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.