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ddrescue, you're my friend.....

Here you can post about what you did to get MEPIS to work right with your computer or if hardware worked right out of the box for you. This is for the computers and/or hardware that is normally hard to get working right in Linux or MEPIS.
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m_pav
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Posts: 2591
Age: 50
Joined: Sun Aug 06, 2006 3:02 pm

ddrescue, you're my friend.....

#1 Postby m_pav » Sun Oct 12, 2014 9:13 pm

My work server had a serious drive failure last Friday after 23744 hours of use.

I began to get some splicing errors that alerted me to a potential fault, but smartctl was not showing any errors, so I rechecked a few times over the last 2-3 weeks and minimised my use of the drive and informed most of my staff of the issue. I had ordered another drive, but it had not yet arrived when one of my part time staffers who did not know of the issue backed up 12GB worth of photos to the server. As he was trying to restore the data, he came to me with his problems. I had that horrible sinking feeling of losing a customers only copy of her overseas trips and I didn't have a 2TB drive to recover to.

A quick check with smartctl showed 24000 reallocated sectors and 12000 pending sectors. The reallocated are OK because that's good data, but the pending sectors, that's bad because the surface is already unstable. I found a 2TB Seagate External drive on special in the next town so grabbed that on Saturday AM and headed into the shop to start the recovery process.

I booted with my localised MX-14 live-DVD and ran the following command once I had worked out the drive placings.

ddrescue -f -d -r3 /dev/sdb /dev/sdc /media/usbflash/2tbcopy.log

After the clone, the numbers grew slightly, which is only to be expected, since the whole drive was scanned from one end to the other.
40976 reallocated sectors, 24208 in the pending sector count, however, there was a problem. The clone had not completed because the destination drive was too small. Turns out there was 12MB difference over a 2TB drive and the retry x 3 did not run - GULP.

Destination drive left in an unknown state, no partition table entry because the process ended prematurely and it looked like I'd have to re-run the scan. The log file reported 450 definitive unreadable positions on the drive and I hoped they were on an unused portion of the drive.

I checked the disk with testdisk and found it had written the first part of a partition entry so things were looking hopeful, so I wrote the changes to the disk and rechecked it with gparted. Now I could see a single unknown partition but I was having to repeatedly close errors about sdc, so I rebooted again into the Live-system, fired up gparted and I was able to run a check on the unknown partition. 40 seconds later, the partition mounted and I could see the familiar structure of my files and customer data.

The good news is, we did not lose her data. That which could not be read on the damaged drive was perfect on the temporary new drive and a hours tinkering this AM before the start of business had my server working flawlessly while I wait for my replacement drive to arrive.
Mike P

Regd Linux User #472293
(Mine)Lenovo T560, i7-6600U, 16GB, 2.0TB SSHD, MX16 64-bit
(Wifes) Asus M4A88TD-M, AMD Phenom II x4 955 CPU, nVidia GF610, 6Gb, 500GB+320GB, MX16 + KDE
(Kids) Intel NUC, J1900, 4GB, 64GB SSD, MX16

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