[SOLVED] Server Data Recovery Via Rescue Mode

michaelk · 09-02-2015, 02:46 PM

It would the error as displayed when you try to boot the computer from the hard drives. I don't see the expected SCSI controller module loading so I will also need the output of the lspci command. You would have to go through the BIOS update release notes to see what changes were made or if booting from USB was mentioned.

I would create a bootable CentOS disc and see what happens.

seth.cannon · 09-03-2015, 10:30 AM

Managed to get CentOS on it due to the upgraded BIOS! I access all of the hard disk information as well, we are just debating on which method to use to get it off. We'd like to do an FTP server, but struggling a bit to get that to work, so we'll probably just plug in an external hard drive.

Thank you so much for the help michaelk.

For completionism, here are the steps that allowed me to get into CentOS (since that was the end goal prescribed by Dell to be able to access the data on the harddrive).

BEFORE I GET INTO THE STEPS I DID TO SOLVE IT: Burning a .iso file to a CD/DVD is different than any other file to a CD/DVD. Once I learned that, these steps took only a couple of hours and I was done. I could have saved a couple of weeks knowing that I couldn't burn it the same way... so double check you burned the iso correctly if you get "No bootable device" when starting your system.

1. Get BIOS Revision A07 iso file on a CD to flash an upgrade to the BIOS Revision A02
Location: http://www.dell.com/support/home/us/...iverId=R186932
File: OEMR-2850-BIOS-A07.iso

2. Throw in the CD and flash the BIOS.

3. Download CentOS iso on a DvD to be able to access rescue mode.
Location: http://linux.dell.com/files/openmana...firmware-live/
File: Centos65-OM74-Firmware-LiveDVD.x86_64-1.1.0-Build6.1.iso

4. Throw in the CentOS DvD.

5. Restart your machine so that the CentOS DvD was in there before it turned on.

6. Load BIOS.

7. Ensure the Boot Sequence step starts with "USB CD...."

8. Continue boot up. When prompted, enter CentOS

9. When CentOS loads, you'll have Firefox and a Terminal window pop up.

10. Use the Terminal window to find your partitions and mount them.

-----a. This will log you into the right spot from the terminal and do setup for mounting: http://blog.zwiegnet.com/linux-serve...-from-live-cd/

-----b. Once in, using fdisk -l or simply finding the /dev directory, determine your partitions.

-----c. Attempt to mount the disk partitions you want to the /mnt/HARDDRIVE you made in 10a (link in 10a also shows how to mount). If you have multiple drives, you may want to use mkdir to create multiple directories under the /mnt folder (one for each).
----------i. Note you have to know the type of the partition. To find out the type, use this: file -sL /dev/sd* or blkid commands (link: http://unix.stackexchange.com/questi...2-ext3-or-ext4)

-----d. If the mount failed due to a corrupt superblock, find the backup superblock. http://www.cyberciti.biz/tips/surviv...-failures.html
----------i. This link shows you how to use mke2fs and dmpe2fs to determine if the superblock is bad and where backup superblocks would be located.
----------ii. Once you know where the superblocks are, use e2fsck to redirect them to the good superblock
----------iii. When using e2fsck, add the -y switch to avoid recursively saying yes to every question
----------iv. Attempt to mount that block again.

11. You can cd into /mnt/HARDDRIVE to see all your files you just mounted. For me I had 10 partitions so I made /mnt/HD1, /mnt/HD2, .... /mntHD10 for convenience. You have several methods of recovery from here. You can FTP off the files, or mount an external drive. When I mounted a USB, it took the same mount command as before, except the drive partition was sdb1 instead of sda*. I'll probably end up doing the same thing for a External Hard Drive since the USB is small compared to the data needed.

---------- If you have an external device that is partitioned as something unreadable on Linux such as NTFS ----------

12. You need to reformat your drive to be ext3. To do this, simply type the command

Code:

mkfs.ext3 /dev/sdb1

or whatever your external drive is connected as.
-----a. This will wipe the drive. Do this if you don't need anything already existing on it.

----------------- You have data on your have a linux drive... but you want to move the data to a Mac -------------------

13. Awesome. Mac can't read ext3. Fortunately there is a helper program that lets it work. First download OSX Fuse for Mac located here: http://osxfuse.github.io/
-----a. When you install this, make sure you check a checkbox that is disabled by default. Instructions: http://techiezone.rottigni.net/2012/...mac-os-x-lion/

14. Download and install a plugin for OSX Fuse called fuse-ext2 located here: http://sourceforge.net/projects/fuse-ext2/

15. Plug in your Hard Drive. Apparently it should automatically be able to be read as read only. It didn't for me. So I continued on to enable the ability to write to the the hard drive, which inherently also gave the ability to read. NOTE that using this function is in beta and is not guaranteed to preserve data, but it seemed to be my only option, and it worked for me as well as for people before me. If you need to do this step, follow these instructions: https://discussions.apple.com/message/20562500#20562500
-----a. When I ran the following command, it immediately said the mount was successful. However, it didn't appear on my desktop for about another minute.

Code:

sudo fuse-ext2 -o force /dev/disk4s1 /Volumes/extDrive

-----b. If you get this error while trying to run the mount on Mac to read, then you need to redownload OSXFUSE and check the checkbox in 13a (this error pops up regardless of using variants with sudo, -o, or force):

Code:

fuse-ext2 /dev/disk3s1 /Volumes/extDrive 
dyld: Library not loaded: /usr/local/lib/libfuse.2.dylib 
  Referenced from: /usr/local/bin/fuse-ext2
  Reason: image not found
Trace/BPT trap: 5

NOTES:

- If you drive has a type of "swap" from the blkid /dev/sda* command, then you don't need it for the data.
- If fdisk -l gives a System extension of "W96 Ext'd (LBA)", you don't need this partition for data (also if the type of a partition would be "swap", then the fdisk -l command will also says its System is "Linux swap / Solaris", so you can technically figure that out with this as well).

michaelk · 09-03-2015, 10:38 AM

Well done.

I agree that an external drive would be the fastest and easiest way to backup your data. Just for information the Ext'd i.e. extended partition is a container for logical partitions (partitions >4 i.e. sda5,sda6...). In a nutshell the method used to create more then 4 partitions for a legacy MBR formatted disk. It does not contain data.

seth.cannon · 09-03-2015, 11:06 AM

Excellent, I changed that "probably" to a definitive not needed for that partition. I knew from googling that I personally didn't need it, but, since I couldn't confirm what it was for, I didn't want to claim that no one would need it without further information... thanks!

Edit: Typo, oops.

seth.cannon · 09-03-2015, 01:19 PM

Sorry to reopen this, but we just got our hands on an external hard drive. However, unlike the flash drive (fs type FAT16/vfat), this has the fs type ntfs. When I tried to mount it, the system said that ntfs was not a recognized fs type. Googling that problem led me to realize that ntfs is windows only, and would have to be installed on linux to get used. I found two sources that tried to get it installed, and both methods failed. The first method:

http://linuxconfig.org/How-to-mount-...ition-software

uses wget to grab it from online. However linux cranks out that wget is not a valid command.

Another method used:
https://support.plex.tv/hc/en-us/art...rives-on-Linux

but the sudo yum install ntfs-3g cranks out a long traceback error that ends with SyntaxError: invalid syntax.

Not sure how to get NTFS working, and really dont want to have to do this all 1 GB at a time. Help would be awesome.

michaelk · 09-03-2015, 01:38 PM

I've never tried to "install" software with a CentOS live disc and do not know if will work. I would reformat the drive as a native linux file system i.e. ext3 instead of NTFS. Copying the files straight to NTFS will not maintain file attributes if that is important. You could create a tar archive but lets keep it simple.

seth.cannon · 09-03-2015, 02:04 PM

Excellent, thanks for the tip. I found a good way to convert it here: http://www.linuxquestions.org/questi...5/#post3063708

The information is currently copying. Once I have the information onto another system, what would be the simplest way to reformat it back to ntfs. I would like to give it back to its original owner in the same condition it was brought it. I saw a couple of possibilities, but most of them involved operating from the Windows environment. While I could give him walk through steps for him to do on his own machine, I'd prefer to do the work for him.

Edit: Bigger problem: ext3 isn't readable by my own Mac, haha.

Edit2: Ok, much bigger problem. I was copying the contents of the eighth of ten partitions. It Seg Faulted. I thought at first, it may be full... but this is a 500GB drive and I'm copying from a drive with 77GB total on it. Further I realized that my command terminal is broken. Every command I enter seg faults (ls, cd, etc). I even tried to exit, successfully. I tried to reenter with sudo su and it seg faulted immediately... What happened? haha.

michaelk · 09-03-2015, 02:14 PM

There is osxfuse which is a fuse file system for mounting ext file systems as well as ntfs-3g. No idea how well it works. In my humble opinion the best method would be to use a windows system to format NTFS.

seth.cannon · 09-03-2015, 03:00 PM

OK, Tried restarting through CentOS and it had another major problem. I hard shut down the server and rebooted. I was able to access it again, remounted everything. Data on the external seemed to still be good. I finished copying partitions 8/9. Working on 10 (with a couple of minor file errors apparently).

However, while this was happening, I tried to plugin to the Mac just so I could copy the files off. However, the Mac claimed it couldn't be read. Is there a recommendation you have to let Mac read the external disk?

michaelk · 09-03-2015, 03:09 PM

Yes, you need to install osxfuse and fuse-ext2 in order to read data on the hard drive. No actual experience, I don't have a Mac.

http://osxfuse.github.io/

seth.cannon · 09-03-2015, 05:00 PM

Alright, so I downloaded osxfuse and fuse-ext2. They both say they install properly... however I don't see anything on my computer other than the downloaded packages. I went ahead and try to follow the instructions here: http://www.cnet.com/how-to/how-to-ma...disks-in-os-x/

When I run the command

Code:

fuse-ext2 -o force /dev/disk3s1 /Volumes/extDrive

I get the following:

Code:

dyld: Library not loaded: /usr/local/lib/libfuse.2.dylib
  Referenced from: usr/local/bin/fuse-ext2
  Reason: image not found
Trace/BPT trap: 5

I don't have time to troubleshoot this one today, but if you have ideas it would be appreciated.

Note: This could be considered Mac territory, not Linux now. If so, I'll go pester another forum. However, just in case you have an idea since I'm still looking to basically running a linux based thing on a Mac, maybe you can still help.

------

Edit: I was able to solve the problem above by following these instructions: http://techiezone.rottigni.net/2012/...mac-os-x-lion/

Yep, that simple. A checkbox that is by default unchecked at installation needs to be checked.

Ran into a new problem:

Code:

fuse-ext2 -o force /dev/disk1s1 /Volumes/extDrive
fuse-ext2: version:'0.0.7', fuse_version:'27' [main (../../fuse-ext2/fuse-ext2.c:324)]
fuse-ext2: enter [do_probe (../../fuse-ext2/do_probe.c:30)]
fuse-ext2: Error while trying to open /dev/disk1s1 (rc=13) [do_probe (../../fuse-ext2/do_probe.c:34)]
fuse-ext2: Probe failed [main (../../fuse-ext2/fuse-ext2.c:340)]

Note: earlier in the post I have disk3s1 listed. Yesterday it was disk3s1, since I rebooted it reset to disk1s1. This is just a disk label for an inserted USB found in Disk Utility.

I solved this problem as well by following these instructions: https://discussions.apple.com/message/20562500#20562500

I don't know why I couldn't just plug in and work as described in the post on the discussions board for apple, but it didn't. I figured if I had write access, then I also had read access, so I decided to try to go for the write access anyway. Using the sudo command worked (took a minute to appear on my desktop after running the command even though the terminal window said it was already successful). Regardless, it works, and I have my data. So yay.

I will edit that master post above to reflect these last steps.