Backup Hard Disks With Bad Sectors

By: Suhaimi Baruddin

What are bad sectors

Heard of bad sectors? Or course you have. It's commonly referenced as one of the causes of computer slowdown, or hard disk crash.

And rightfully so. A bad sector is a permanent damage to the hard disk platter, which by the way, is where your data is stored. If any data is written to the bad sector, that piece of data cannot be accessed anymore.

Causes of bad sectors

Since bad sectors are a physical anomaly of the hard drive, the causes are also of physical nature.

Hard drives, by default, have bad sectors already fresh out of the box. Although hard disk manufacturers can eliminate the bad sectors totally, the procedures and the resources consumed will make it impossible to market hard disks at its current low price.

Physical shocks to the computer (dropping of laptop, kicking, etc.) can affect the hard disk. When this happens, there is a possibility that damages to the platter of the hard disk can occur, which causes bad sectors to form. This kind of damage can literally cause a head crash when the hard drive is in operation.

Heat, resulting from extensive use, bad ventilation or poor housekeeping of your computer system, can also cause bad sectors to occur. This is due to the fact that hard disks work on the principles of magnetism.

Or, the bad sectors could simply form over time, as hard disks lose their magnetic properties. This is a "natural" degradation of the hard disk and users should be aware of this, and replace their hard disks once it has been in use over a period of time.

Superparamagnetic limit

Over time, manufacturers will try to fit as much data on one platter as they can, increasing the data density on the hard disk platter.

The superparamagnetic limit in hard drives is a limit set on the storage density of hard disks due to the particle size of the magnetic elements on the platters. With the increasing density of data on the platter, the tolerance for failure is decreased.

Looking out for bad sectors

Even though bad sectors are a physical anomaly in hard disk, this does not mean that you can actually physically see it. Instead, there are a few applications (or sometimes, signs) that can enable you to detect bad sectors.

There is a system on most computers, called the Self Monitoring Analysis and Reporting Technology (or S.M.A.R.T.) is a technology that enables a computer system to predict the future failure of storage device, in theory anyways.

This feature is supported in Windows version 95 onwards, and can be accessed through BIOS, as by default, it is disabled.



One other option is to use Window's resident checking application, chkdsk. This application can do both quick and full surface scans.

Of course there are other good external applications such as ADRC's very own hard disk checker. It is free, and requires no installation.

Also, some hard disk manufacturers have their own hard disk utility programs, where their application will scan the hard disk for any problems. The companies that have these applications are Maxtor, Seagate and Western Digital.

Backing up drives with bad sectors

Bad sectors can cause your computer to be almost unusable, crashing left and right and preventing you from accessing and backing up your data.

If there is any critical data on the hard drive, you need to quickly transfer the data onto another hard disk (or any other media) before the disk crashes (GASP) on you, taking your data along with it. However, you need to check if you suffer only from bad sectors and not physical failures (signs which include clicking, grinding, scraping sounds).

Get an external drive to backup the data to. However you need to get a hard drive which is at least the same capacity as the old drive. I recommend however that you get a drive of a bigger capacity just in case.

Step 1

First you need to install the hard disk as a secondary drive. Remove it from your computer and install it into another computer. If you are using and IDE drive, you need to set the drive as a secondary drive. If you are using a SATA drive, adjust in BIOS accordingly.

Method 1: Copy Files

As there we are copying from a hard disk with bad sectors, normal copy and paste will not do since if the data is being copied from a bad sector, the copy process will get interrupted/hang/freeze and fail. Again, we are going to use another freeware from ADRC.

ADRC Data Recovery Tools

Download, unzip and run the application.

Under the tools menu, select "copy files". Select the source location (the disk with bad sectors) and the target location (the backup disk) and press "start copy".

Why are do we need the software though? What's the difference? Isn't it the same as copying like in click-and-drag?

No. For one, the software has and inbuilt function where even if parts of a file is corrupted due to bad sectors, it will search the neighbouring sectors to determine the extent of the bad sector blocks, and automatically calculate how many retries are needed and reduce the number of retries over the bad sector blocks.

Once it does, it will then recovery every readable bits of a file and put them together to salvage your data, thus at the very least some parts of the file is recovered. This is still much better than having everything gone.

The application also has an option, "Copy Sub Folders" where it scans through the entire directory and tries to copy everything you need.

"Copy files" is works well when you want to only copy certain files and folders and not the whole drive. If you want to copy the whole disk, you need to utilise another function, "raw copy".

Method 2: Ghosting

If you want to copy the whole disk to a new one and do not want to reinstall the operating system.

Still using the same ADRC data recovery tools, select "raw copy" under tools. Then simply select the source disk (the disk you want to backup) and the target disk (the disk you want to backup to)

Then simply click transfer and wait for the operation to finish.

Results!

If you are lucky, you will have recovered backed up almost everything in the drive. However, if you wait too long to backup the data on a badly infected (with bad sectors) disk, some data may get corrupted and inaccessible.

Data Recovery
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