Recovering Bad Hard Disks (CRC on Windows, Error –36 on Mac OSX)

So you've been vis­ited by the much dreaded CRC — Cycli­cal Redun­dancy Check error, most likely encoun­tered while copy­ing files between hard disks. On Mac OSX, this will usu­ally appear as some cryp­tic per­mis­sions mes­sage with an Error –36.

To cut the geek-speak, this sim­ply means that you hard disk may have cer­tain files that may have "bad sec­tors", or are cor­rupted in other words.

For­tu­nately, this is a com­mon enough prob­lem in our tech­ni­cally advanced world of exter­nal stor­age. I rec­om­mend solv­ing this on Win­dows (I use both XP and OSX Leop­ard at the time of this writing).

Step 1: CHKDSK

Use what Win­dows offers you by default. The chkdsk com­mand. Just open an MS-DOS com­mand prompt win­dow and go to the drive you wish to check (I'm hop­ing you already know your way around a com­mand prompt; if you don't please con­sider Step 2 below). With the com­mand prompt show­ing the drive let­ter of the disk you wish to check, enter this command:

e:> chkdsk /R

Here, "e:" is my drive to be checked. The "/R" attribute asks the chkdsk com­mand to "recover" what­ever bad sec­tors it finds dur­ing its scan. In most cases, and if you're lucky, this ought to do it.

Step 2: CDCheck (Free)

Only if the prob­lem you were fac­ing still remains after you have run the chkdsk com­mand, should you con­sider doing this. This is a free­ware pro­gram that makes it super-easy to check/recover your disk. It can be any disk – your cur­rent hard disk, a CD or a DVD, or even an exter­nal hard disk. The inter­face is pretty sim­ple as you can see in the screen­shots here.

Step 3: Spin­Rite (US$ 90)

If all else has failed, just save your­self some heart­burn and go straight to Spin­Rite. This is hands-down the best soft­ware for this pur­pose, as any­one in a dire need of data recov­ery will con­firm. I would trust any piece of soft­ware from GRC. Only catch: it's not free, but when you use it you know why it's worth every last cent. It gives you a sim­ple option to save an ISO file, which you can then eas­ily burn on to a CD using any CD writer tool (includ­ing Win­dows' own right-click). Then reboot your machine so it starts from the CD. Spin­Rite will auto­mat­i­cally report and recover what­ever is recoverable.

Next Steps

Basi­cally, a CRC error is the begin­ning of the end. If this is on an exter­nal hard disk, I highly rec­om­mend that you con­sider back­ing up the data immediately.

  • del­phi­son

    Thanks, CD Check is a great tip!

  • David

    So what do you do if you're a Mac user??