Manually marking sectors bad/used

jef_pearlman · 10-07-2004, 12:18 AM

Hi. I have an external drive (well, technically an iPod) with a small set of bad sectors. I know generally what region of the drive they're in and within what range of sectors, but on some of them, if an attempt is made to read or write it, it simply locks the drive. The result of this is that I can't use the drive, because eventually some data ends up in that area, locking the drive. Similarly, I can't use surface scan software to mark the sectors bad, because the drive interface locks when it gets to that sector.

So what I'm looking for is a program or piece of source code that (even with some coding work) will let me take a bunch of sector or block numbers and either 1) mark them bad or 2) create a file that specifically includes those sectors. Then, I should be able to use the vast majority of the drive which is fine -- only about 32k out of 5 gigs is bad.

Incidentally, badsect doesn't seem to work. I've read a bunch of posts on the net and poked around the source myself, and for whatever reason it doesn't seem like it's going to do its job on OS X.

Also, I'm also willing to use FAT/FAT32 and a PC to do this, if anyone knows how. I can use a PC-formatted drive on my Mac with no problem.

Thanks!

-Jef

chabig · 10-07-2004, 08:33 PM

As far as I know, mapping out bad sectors is a function of the drive's firmware. All you can do it try to reformat the drive. So I'd try formatting it with Disk Utility, and then restore iPod functionality using the iPod Updater.

Chris

Las_Vegas · 10-08-2004, 12:34 AM

If the drive has bad sectors that cause problems, the drive is gone. The bad sector map is filled and somehow the media has become physically damaged. There may be utilities that will hide those sectors, but likely the damage is much more severe and will only get worse.

Open Disk Utility with the iPod attached. Select the drive and click the "Info" icon. Take note of the S.M.A.R.T. status. It should report the condition of the drive.

jef_pearlman · 10-10-2004, 04:19 PM

A couple of things. First, the drive isn't reporting SMART status, probably because it's external/firewire.

The problem is that there was a small portion of the disk which was physically damaged at one point. It's too much for the internal remapping to fix, but it's localized to one portion of the disk. So if I can use the filesystem's bad sector mapping (I know FAT has it, I don't know about HFS/HFS+), or if I can just create a file which includes those sectors, the drive will run fine.

For the reasons I mentioned above, I can't just format it (zeroing it out) with Disk Utility. If I use the zero out option, when it gets to the bad portion of the disk, it just locks up.

Thanks!

-Jef

acme.mail.order · 10-10-2004, 07:57 PM

What you are attempting to do makes sense, but it requires device-driver-level control of the drive. You need to create an entry in the directory using specific sectors without actually writing the file. If you can find an appropriate drive sector editor it can be done, but I haven't seen one of those in ages. If you can code one yourself, more power to ya!

Is it worth the effort? You are out of spare sectors (otherwise you would never know of the problem) and if there was a head crash your heads are probably damaged as well. So, your drive (and data) are living on borrowed time. Given the cost of repair vs. time needed to delay the inevitable, If it were mine I'd say it's time for an upgrade. iPod mini, royal blue perhaps?

jef_pearlman · 10-10-2004, 11:34 PM

I got it working. (Odd, I've been working on this for like a month, but as soon as I post, I figure it out.)

I restored my iPod (basically formats HFS+ and reflashes). Then I touched a file called "Bad" on the iPod (creating a 0-length file). Using Norton Disk Editor, I opened the B-tree record window for that file, and added an extent with range of blocks for that file that I knew included the bad sectors. Then I saved, umounted the drive, and ran disk utility/fsck on it (because I hadn't allocated those blocks in the usual way, it had to repair a bunch of bookeeping data on free blocks). Then I remounted, and used the ipod like normal, with that file allocated to cover all the bad blocks. Interestingly, the logical length of the file is still 0, but there are still 200 megs of blocks allocated to it.

Also interestingly, adding 100 megs still had trouble, but adding 200 megs different. So that's about how narrowly I know where the bad blocks are.

Thanks for the suggestions, guys.

-Jef

p.s. Buying a new one was not an option. This one was free (two people gave me broken ones which I combined to make this one with a semi-flaky drive).

10-07-2004, 12:18 AM	#1
jef_pearlman Prospect Join Date: Oct 2004 Posts: 14	Manually marking sectors bad/used Hi. I have an external drive (well, technically an iPod) with a small set of bad sectors. I know generally what region of the drive they're in and within what range of sectors, but on some of them, if an attempt is made to read or write it, it simply locks the drive. The result of this is that I can't use the drive, because eventually some data ends up in that area, locking the drive. Similarly, I can't use surface scan software to mark the sectors bad, because the drive interface locks when it gets to that sector. So what I'm looking for is a program or piece of source code that (even with some coding work) will let me take a bunch of sector or block numbers and either 1) mark them bad or 2) create a file that specifically includes those sectors. Then, I should be able to use the vast majority of the drive which is fine -- only about 32k out of 5 gigs is bad. Incidentally, badsect doesn't seem to work. I've read a bunch of posts on the net and poked around the source myself, and for whatever reason it doesn't seem like it's going to do its job on OS X. Also, I'm also willing to use FAT/FAT32 and a PC to do this, if anyone knows how. I can use a PC-formatted drive on my Mac with no problem. Thanks! -Jef

10-08-2004, 12:34 AM	#3
Las_Vegas League Commissioner Join Date: Sep 2004 Location: Las Vegas Posts: 5,875	If the drive has bad sectors that cause problems, the drive is gone. The bad sector map is filled and somehow the media has become physically damaged. There may be utilities that will hide those sectors, but likely the damage is much more severe and will only get worse. Open Disk Utility with the iPod attached. Select the drive and click the "Info" icon. Take note of the S.M.A.R.T. status. It should report the condition of the drive. __________________ Las_Vegas -- Ts'i mahnu uterna ot twan ot geifur hingts uto. -- Sometimes I wonder… Why is that Frisbee getting Larger? …and then it hits me. -- Disposable thumbs make me specialer than most animals…

10-07-2004, 08:33 PM	#2
chabig Hall of Famer Join Date: Jan 2002 Posts: 2,851	As far as I know, mapping out bad sectors is a function of the drive's firmware. All you can do it try to reformat the drive. So I'd try formatting it with Disk Utility, and then restore iPod functionality using the iPod Updater. Chris

10-10-2004, 04:19 PM	#4
jef_pearlman Prospect Join Date: Oct 2004 Posts: 14	A couple of things. First, the drive isn't reporting SMART status, probably because it's external/firewire. The problem is that there was a small portion of the disk which was physically damaged at one point. It's too much for the internal remapping to fix, but it's localized to one portion of the disk. So if I can use the filesystem's bad sector mapping (I know FAT has it, I don't know about HFS/HFS+), or if I can just create a file which includes those sectors, the drive will run fine. For the reasons I mentioned above, I can't just format it (zeroing it out) with Disk Utility. If I use the zero out option, when it gets to the bad portion of the disk, it just locks up. Thanks! -Jef

10-10-2004, 07:57 PM	#5
acme.mail.order League Commissioner Join Date: Sep 2003 Location: Tokyo Posts: 6,010	What you are attempting to do makes sense, but it requires device-driver-level control of the drive. You need to create an entry in the directory using specific sectors without actually writing the file. If you can find an appropriate drive sector editor it can be done, but I haven't seen one of those in ages. If you can code one yourself, more power to ya! Is it worth the effort? You are out of spare sectors (otherwise you would never know of the problem) and if there was a head crash your heads are probably damaged as well. So, your drive (and data) are living on borrowed time. Given the cost of repair vs. time needed to delay the inevitable, If it were mine I'd say it's time for an upgrade. iPod mini, royal blue perhaps?

10-10-2004, 11:34 PM	#6
jef_pearlman Prospect Join Date: Oct 2004 Posts: 14	I got it working. (Odd, I've been working on this for like a month, but as soon as I post, I figure it out.) I restored my iPod (basically formats HFS+ and reflashes). Then I touched a file called "Bad" on the iPod (creating a 0-length file). Using Norton Disk Editor, I opened the B-tree record window for that file, and added an extent with range of blocks for that file that I knew included the bad sectors. Then I saved, umounted the drive, and ran disk utility/fsck on it (because I hadn't allocated those blocks in the usual way, it had to repair a bunch of bookeeping data on free blocks). Then I remounted, and used the ipod like normal, with that file allocated to cover all the bad blocks. Interestingly, the logical length of the file is still 0, but there are still 200 megs of blocks allocated to it. Also interestingly, adding 100 megs still had trouble, but adding 200 megs different. So that's about how narrowly I know where the bad blocks are. Thanks for the suggestions, guys. -Jef p.s. Buying a new one was not an option. This one was free (two people gave me broken ones which I combined to make this one with a semi-flaky drive).