Phuket Information Technology Blog » Data Recovery

Matching Linux ata numbers to the device names

admin — Sat, 16 Jul 2011 11:13:25 +0000

Many thanks to Dirk Tilger for the information on his blog. I am just providing the more manageable commands to type

Recently we had to recover data from a 8-drive soft-RAID5 on Linux. It had 3 devices failed out of 8. 2 of the drives just had some bad sectors on them. The problem is, the Linux kernel reports errors on the device as ata channel numbers, for example as “ata1.00″. All 8 drives were the same model, the serial number is not reported via dmesg, so how to know the device name (like /dev/sda) that is causing these error messages?

The command

grep '[0-9]' /sys/class/scsi_host/host{0..9}/unique_id

will provide output like this:

/sys/class/scsi_host/host0/unique_id:1
/sys/class/scsi_host/host1/unique_id:2
/sys/class/scsi_host/host2/unique_id:0
/sys/class/scsi_host/host3/unique_id:0
/sys/class/scsi_host/host4/unique_id:3
/sys/class/scsi_host/host5/unique_id:4
/sys/class/scsi_host/host6/unique_id:5
/sys/class/scsi_host/host7/unique_id:6

so we can match the unique id used in kernel error messages to the host number. Then the command:

ls -l /sys/block/sd*

Will show us which device name belongs to which host number:

/sys/block/sda -> ../devices/pci0000:00/0000:00:13.2/usb1/1-6/1-6:1.0/host2/target2:0:0/2:0:0:0/block/sda
/sys/block/sdb -> ../devices/pci0000:00/0000:00:13.2/usb1/1-8/1-8:1.0/host3/target3:0:0/3:0:0:0/block/sdb
/sys/block/sdc -> ../devices/pci0000:00/0000:00:12.0/host6/target6:0:0/6:0:0:0/block/sdc
/sys/block/sdd -> ../devices/pci0000:00/0000:00:13.2/usb1/1-8/1-8:1.0/host3/target3:0:0/3:0:0:1/block/sdd
/sys/block/sde -> ../devices/pci0000:00/0000:00:13.2/usb1/1-8/1-8:1.0/host3/target3:0:0/3:0:0:2/block/sde
/sys/block/sdf -> ../devices/pci0000:00/0000:00:13.2/usb1/1-8/1-8:1.0/host3/target3:0:0/3:0:0:3/block/sdf
/sys/block/sdg -> ../devices/pci0000:00/0000:00:12.0/host7/target7:0:0/7:0:0:0/block/sdg

From these two outputs we can see that the unique id 6 maps to host7, and host7 maps to /dev/sdg. And finally, with the command:

hdparm -i /dev/sdg

/dev/sdg:
 Model=ST3500418AS, FwRev=CC34, SerialNo=6VM2KSFD

we can find the serial number of the drive.

100% data recovered after HDD is fully immersed in water for 2 hours

admin — Wed, 12 Aug 2009 12:47:35 +0000

Two nights ago thieves stole a notebook from an office of our customers but had to abandon it because they were noticed. They run away and threw a notebook into a drainage ditch full of water. Notebook was found only 2 hours after. Today we finished a hard cleanup and recovery and retrieved 100% of data.

Data Recovery from SCSI HP HDD

admin — Thu, 16 Apr 2009 18:18:44 +0000

We successfully recovered 100% of data from HP SCSI HDD for Faculty of Medicine, Songkla University.
HP BD03695A27 is actually a re-branded Seagate drive. Disk was showing a “Medium Error” on the controller, the capacity recognized by the controller was wrong – 100000 sectors. This a typical translator problem occurring on the Seagate SCSI drives. The recovered image was cloned to the identical drive and the engineers at the Songkla University were able to boot and use the server the same way as before the crash.

Organize JPEG files by EXIF data

admin — Sat, 07 Mar 2009 15:09:57 +0000

I was looking for a better way to rename more than 20000 recovered JPEG files where original file names and folders were lost. I used to do it with our homegrown Perl script. I finally found a nice free utility: AmoK EXIF Sorter. It can rename files and move them to the folders according to your naming schema, for example:

\Year-Month\Camera_name-day-hour-minute.jpg

Don’t shout at your hard disk drives

admin — Sat, 03 Jan 2009 09:25:26 +0000

http://www.youtube.com/watch?v=tDacjrSCeq4

Erasing with 0′s once is enough

admin — Sat, 03 Jan 2009 04:58:54 +0000

It’s a shame I did not see this challenge site before: The Great Zero Challenge. Maybe at least this one will stop some “IT Professionals” boasting about their favorite “professional data eraser” programs. The point is simple: no data recovery company ever recovered anything from the modern hard disk drive simply overwritten with zeros once. With the HDD technology advances the famous Gutman paper is not valid for a modern hard drives for a quite long time already.

Digital Cameras File System Corruption

admin — Tue, 09 Dec 2008 04:23:08 +0000

Quite a few digital cameras corrupt FAT filesystem when the flash card becomes full. Luckily the images in this case are fully recoverable.

Seagate SCSI recovery: Medium Error, Read Capacity Failed problem

admin — Mon, 31 Mar 2008 15:05:17 +0000

With a help of our new SCSI data recovery complex, we pulled 100% of Microsoft Exchange databases from a Seagate SCSI drive belonging to British Curriculum International School. The kind of a failure was quite common for Seagate SCSI drives: SCSI controller shows “Medium Error”; Drive Capacity is indicated as 0 (or in Linux logs the message “Read Capacity failed” can be seen), the drive serial number is displayed correctly in the diagnostic utilities.

Another Toshiba HDD with a bearing problem

admin — Mon, 31 Mar 2008 14:53:18 +0000

Another successful data recovery from a Toshiba hard disk drive with a bearing problem (this drive has a fluid dynamic bearing). Actually Toshiba is an absolute leader for this kind of HDD failures. This time we recorded an MP3 for you, how the drive sounded when it was brought to us:

Toshiba HDD bearing problem

SCSI Data Recovery Suite

admin — Tue, 18 Mar 2008 19:45:54 +0000

Our new SCSI data recovery hardware/software complex should arrive soon, allowing us to do certain new things with SCSI drives we was not able to do before.