External Hard Drive acting funny

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Level 1

20 points

External Hard Drive acting funny

I'm not sure this is the right place for this topic, so I apologize in advance for any blunder on my part.

My external hard drive has been acting strangely. It's a 250 GB LaCie. I use it to back stuff up, or to render movies on (Scratch Disk). I haven't used it for a couple weeks (vacation!), so it's been empty for a little while. However, when I began to add stuff last week, it began stalling my computer (beach ball). I erased the whole thing using Disk Utility after a failed Repair Disk, and ran a Repair Disk again. It told me no repairs were necessary. I've just begun to add stuff to it again. It's stalling again. When I use Disk Utility, I get the following:

Verify and Repair disk “Backup”
Checking HFS Plus volume.
Checking Extents Overflow file.
Checking Catalog file.
Invalid sibling link
Volume check failed.

Error: The underlying task reported failure on exit

1 HFS volume checked
1 volume could not be repaired because of an error

Is my disk dying? Can Disk Utility help me anymore, or should I buy DiskWarrior or TechTools? I note that there is nothing of importance on the disk (I have a duplicate on the drive in my computer).

Thank you in advance.

PowerMac G5, Mac OS X (10.4.7), 1.25 GB RAM, ATI Radeon 9600 XT 128 MB

Posted on Jul 19, 2006 5:17 PM

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Answer 1

Best reply

Thomas Bryant

Level 6

13,881 points

Jul 19, 2006 6:48 PM in response to WiresAP

Hello! The physical disk is probably ok but the directory (road map if you will to the various parts) is damaged. DU sometimes won't fix it but DiskWarrior likely would as TechTool might. Disk Warrior is considered the best. Reformatting would probably fix it but you would lose all your data. Erasing(formatting) using the zero option will lock out any bad sectors and is recommended if the disk is a year or two old. Below is a better explanation I found on the web. Tom

To explain sibling links, first you need to
understand that most directory
information on Macintosh disks is stored
in data structures that are technically
known as B*-trees. Examples of B*-trees
on a Macintosh disk include the Catalog
File, the Extents Overflow File, the
Desktop Database, the Users & Groups
File, and several others.
Each tree has a number of data records;
for example, each record within the
Catalog tree describes one file or one
folder. The records are sorted and
indexed for fast searching. But for
efficiency, the records are also grouped
into fixed-length blocks called nodes;
because these nodes can be physically
scattered around the B*-tree file, they
need pointers to indicate their logical
ordering. So a given node has a "forward
link", which points to the node containing
records that are logically immediately
after the records in the current node;
likewise, a node has a "backward link",
pointing to the node containing logically
preceding records.
If these linkages are pointing to the wrong
place, some files or folders might be
inaccessible. Or the OS could even hang
up trying to find some. This makes the
link invalid.

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Answer 2

WiresAP Author

Level 1

20 points

Jul 20, 2006 6:18 AM in response to Thomas Bryant

I tried to do a Disk Erase with a zero-out option (Mac OS 9 drivers off) and got the following:

Disk Erase failed
Disk Erase failed with the error:

Input/output error

I note that I had just erased the drive (a week or so ago), admittedly without the zero-out option.

Should I try zero-ing out again? Does DiskWarrior allow me to test the hard drive?

Thanks in advance.

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Answer 3

Jul 20, 2006 2:26 PM in response to WiresAP

Hello! You can try the zero option again but when it fails the erase using the zero option there's a likelyhood of so many bad sectors that the disk may be unuseable. Tom

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Answer 4

WiresAP Author

Level 1

20 points

Jul 23, 2006 7:05 AM in response to Thomas Bryant

I tried to zero out two more times. Both times I go the read in/out error, same as before. How may I check with certainty that the disk is totally unusable?

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Answer 5

The hatter

Level 9

60,980 points

Jul 23, 2006 9:20 AM in response to WiresAP

I use Intech Speedtools to check the media an you can tell it to auto map out bad blocks.

ZoneBench can be set to test 50 zones per partition, 511MB test file size, and read-write cycle of 12. I had one drive that continually gave me trouble. ZoneBench shows that there is/was one large area where I/O drops from 58MB/sec down to 31MB/sec as it has to access alternate sector for those blocks, but no more trouble. Makes a fine backup drive now.

If you are just using Disk Utility, then you would want 7-way write/erase instead of writing zeroes (which does only a marginal or superficial job).

TechTool Pro 4.5.1 would be another choice to check media.

I am sure you could use the Terminal and write x'FF' to every block, maybe in 10GB chunks and the drive really should do the re-allocation and assign new blocks from spares.

TTP4 and Speedtools also let you see more of the details that the drive logs to itself and which are part of SMART feature set (IO errors, retries, bad block grown list, etc).

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