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#1 2022-11-13 23:03:57

Registered: 2019-07-18
Posts: 302  

Hdd CHS values... recover files

Hi, I had a small hdd fail.

The mini/laptop sized 3 terrabytes was in a portable enclosure (retail store) with a usb interface.

Now, ...

When I check and see the CHS values when using dd(_)rescue the values lead to only about 4 Gb of space.

So, I figure... when I get the correct values I may be able to scrape some music files off it.

Disk /dev/sde - 4142 MB / 3950 MiB - ST3000LM016-1N217V
     CHS 503 255 63 - sector size=512

There was only one partition on the disk. It was originally fat32, but I changed it to ext4 for my purposes.

The drive failed originally from a broken usb connector. Remove drive and use as sata.

From what I can figure out, the drive had 3 (three) platters = 6 heads(?)

I've tried to guess/estimate but haven't been able to get it just right.

Has anyone here any knowledge of what the chs values are?

I tried changing the superblock (the original error was "can't find superblock"), but none were productive.

I haven't tried photorec yet.

It seems like the chs setting of the drive have been changed (I don't know how).

Manuf date... 21July2016

Verifying with the serial number at seagate's website...
Sep 28, 2021

Bytes per Sector (logical/physical) 512/4096
    Hard Disk Model: SEAGATE ST3000LM016
    Disk Family: Laptop HDD
    Form Factor: 2.5″
    Capacity: 3 TB (3 x 1 000 000 000 000 bytes)
    Number Of Disks: 3
    Number Of Heads: 6
    Rotational Speed: 5400 RPM
    Rotation Time: 11.11 ms
    Average Rotational Latency: 5.56 ms
    Disk Interface: Serial-ATA/600
    Buffer-Host Max. Rate: 600 MB/seconds
    Buffer Size: 131072 KB
    Average Seek Time: 12 ms
    Width: 69.85 mm (2.75 inch)
    Depth: 100.35 mm (3.95 inch)
    Height: 15 mm (0.59 inch)
    Weight: 200 grams (0.44 pounds)
    Required Power For Spinup: 1200 mA
    Power Required (Seek): 2.1 W
    Power Required (Idle): 1.9 W
    Power Required (Standby): 0.18 W
    Manufacturer: Seagate Technology

I have looked at LBA mode and smartctl but have no success.

Any advice appreciated.


#2 2022-12-01 22:17:20

Registered: 2021-10-28
Posts: 38  

Re: Hdd CHS values... recover files

with today's larger drives, the CHS figures are always a fudged number. You need to dig into the definitions of all of these numbers in all the modes. There used to be a program that would let you unravel the numbers that work, but I cant remember what it was called. I will try and look though my older files to see if I can find it.


#3 2022-12-02 01:58:04

Registered: 2019-07-18
Posts: 302  

Re: Hdd CHS values... recover files

I found this website that does calculations...

I have had a go at entering the lba sectors, but it still maxed out at a few gigabytes.

It's out of a portable hdd usb plugs.


#4 2022-12-02 03:08:42

From: Clifton Hill, Victoria, AUS
Registered: 2016-11-30
Posts: 781  

Re: Hdd CHS values... recover files

My 3 TB usb disk says:

root@mini:~# hdparm -g /dev/sdb

 geometry      = 2861588/64/32, sectors = 5860533164, start = 0

and also

root@mini:~# fdisk -l /dev/sdb
Disk /dev/sdb: 2.73 TiB, 3000592979968 bytes, 5860533164 sectors
Disk model: External USB 3.0
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt


#5 2022-12-02 06:25:06

Registered: 2017-05-15
Posts: 129  

Re: Hdd CHS values... recover files

Do you have a larger HDD with at least 3TB of free space? If so, you should make an image backup of the drive using GNU ddrescue.

Package info:

If you're interested, I may have some links to some ddrescue tutorials. I need to look for them, and it's past my bedtime, so it will have to wait until later.

“Your only limitations are those you set up in your mind, or permit others to set up for you.”
— Og Mandino


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