Time Machine IS killing or corrupting disks

I think it is obvious to anyone who has experienced the problem that Time Machine is at fault. The people who are calling it a coincidence don't know what they're talking about.

I have done extensive read/write tests on my brand new external hard drive - at least 500gb in and about half of that back out. All without a single error.

Yet whenever time machine runs, which transfers a few hundred megs maybe each time, I end up with an error and a corrupted disk.

It is highly unlikely that all of us are having hard drive problems that are only showing up when time machine is running.

If this was a coincidence- and the hard drives are at fault, we would have similar reports for any program that writes a lot to the disk. For example, we'd have a bunch of reports in here saying "installing Leopard corrupted my disk"

I would suggest that you provide feedback to Apple via http://www.apple.com/feedback/macosx.html with your findings. That way, they are aware of what you are finding. I am not sure how much they monitor these discussions.

I did an fsck on my Time Machine disk (Firewire external hardrive) which is formatted in HFS+ journaled, and no errors found, my disk is fine, even if I'm using it with Time Machine for all the past week.

So apparently the bug you mention doesn't affect all drives.

I'm using a couple of 500GB Lacie's, no problems at all, but I have noticed that a lot of the affected drives mentioned in the forum seem to be MyBook's.

It would be interesting to see which drives are failing, as well as the Interface Type and Chipset.
I remember that there were problems with some Oxford FireWire Chips when people upgraded to Panther.
People with problems with Time Machine should post with:
* Interface (USB2.0, FireWire 400, FireWire 800, eSATA, Internal SATA, Internal IDE)
* Chipset (Prolific PL3507, Oxford, etc)
* Harddrive Manufacturer (WD, Hitachi, etc.)

I had a Samsung 320Gb drop everything when connected through an Oxford-based enclosure (MacPower IceCube), but haven't had a problem with it in a cheap "Laser" Enclosure with a Prolific PL3507.

HFS+ volumes do not have a superblock. If you mistakenly run fsck rather than fsck_hfs to diagnose a volume other than the active startup volume, you always get that diagnosis. If you run fsck to diagnose the active startup volume, fsck calls fsck_hfs, and it runs instead.

Homemade RAID with a pair of 250GB Seagates in a dual enclosure, not experiencing this problem.

One thing I've learned about PC-formatted drives (like the various WD MyBooks) that you can buy at Staples ... Mac users should ignore all software and setup instructions that come with it. Just plug in and use Disk Utility to format or partition it as Mac OS Extended (Journaled). Those drivers and button managers that come on the drive or CD, even Mac versions, are nothing but trouble and are better off NOT brought into your Mac system.

Mac-formatted drives by Lacie and others are a different story.

No problems here either. I think this is a case of a misdiagnosed problem paired with inexperienced users.

However, I've noticed there is little information for Time Machine and little error control on the applications part to alert the user of possible issues (for example the backing up to a FAT file system). So it is a little difficult to just assume it is a software problem--more of a support problem for non-apple Hardware.

[J]

Charles E. Flynn wrote:
HFS+ volumes do not have a superblock. If you mistakenly run fsck rather than fsck_hfs to diagnose a volume other than the active startup volume, you always get that diagnosis. If you run fsck to diagnose the active startup volume, fsck calls fsck_hfs, and it runs instead.

That's interesting. Wikipedia also describes a "superblock" as a feature specific to the Unix File System…

This might answer some of the questions on HFS+, http://en.wikipedia.org/wiki/HierarchicalFileSystem

HTH

The volume structure on an HFS+ volume that is comparable to the superblock of a UFS volume is the volume header, or volume information block (VIB).

Apple has a detailed description of the HFS+ Volume format:

http://developer.apple.com/technotes/tn/tn1150.html

Micromat posted in the MacFixIt Forums some instructions for viewing the text representation of the volume header, using the free utility hfsdebug:

Use hfsdebug to view volume header:

syntax given on page 1494 of “Mac OS X Internals” by Amit Singh.

Using your browser, go to http://www.osxbook.com/software/hfsdebug/ . Download hfsdebug from the link at the bottom of the page. After the download is complete, double-click the .dmg file you downloaded. When this disk image mounts, you see a free utility named hfsdebug. Copy the hfsdebug file to your desktop.

Open Terminal, located in /Applications/Utilities. Type the following three commands, each on its own line, and press the Return key at the end of each line:

cd ~/Desktop
chmod u+x hfsdebug
sudo ./hfsdebug -d /dev/rdisk1s10 -v


Enter your administrative password at the prompt.

Here is a sample of the output:

MMT3s-Computer:~ MMT3$ cd ~/Desktop
MMT3s-Computer:~/Desktop MMT3$ chmod u+x hfsdebug
MMT3s-Computer:~/Desktop MMT3$ sudo ./hfsdebug -d /dev/rdisk1s10 -v
Password:
# HFS Plus Volume
Volume size = 9699188 KB/9471.86 MB/9.25 GB
# HFS Plus Volume Header
signature = 0x482b (H+)
version = 0x4
lastMountedVersion = 0x4846534a (HFSJ)
attributes = 00000000000000000010000100000000
. kHFSVolumeUnmounted (volume was successfully unmounted)
. kHFSVolumeJournaled (volume has a journal)
journalInfoBlock = 0x1993a3
createDate = Tue Oct 11 20:35:24 2005
modifyDate = Wed Oct 11 21:23:41 2006
backupDate = Fri Jan 1 00:00:00 1904
checkedDate = Tue Oct 11 20:35:24 2005
fileCount = 178583
folderCount = 47879 /* not including the root folder */
blockSize = 4096
totalBlocks = 2424797
freeBlocks = 693970
nextAllocation = 2343707
rsrcClumpSize = 65536
dataClumpSize = 65536
nextCatalogID = 265932
writeCount = 8163599
encodingsBitmap = 00000000000000000000000000000000
00000010000000000000000000001111
# Finder Info
# Bootable system blessed folder ID
finderInfo[0] = 0x1f7ca (LaCie_Boot:/System/Library/CoreServices)
# Parent folder ID of the startup application
finderInfo[1] = 0
# Open folder ID
finderInfo[2] = 0
# Mac OS 9 blessed folder ID
finderInfo[3] = 0
# Reserved
finderInfo[4] = 0
# Mac OS X blessed folder ID
finderInfo[5] = 0x1f7ca (LaCie_Boot:/System/Library/CoreServices)
# VSDB volume identifier (64-bit)
finderInfo[6] = 0xcd566ff7
finderInfo[7] = 0x351c415f
# File System Boot UUID
UUID = 38178E0C-3CC2-37E3-8E87-B5C2662DCF95
# Allocation Bitmap File
logicalSize = 659456 bytes
totalBlocks = 161
fork temperature = /* Metadata Zone */
clumpSize = 356352 bytes
extents = startBlock blockCount % of file
0x74b86 0xa1 100.00 %
161 allocation blocks in 1 extents total.
161.00 allocation blocks per extent on an average.
# Extents Overflow File
logicalSize = 5242880 bytes
totalBlocks = 1280
fork temperature = /* Metadata Zone */
clumpSize = 5242880 bytes
extents = startBlock blockCount % of file
0xa98c9 0x500 100.00 %
1280 allocation blocks in 1 extents total.
1280.00 allocation blocks per extent on an average.
# Catalog File
logicalSize = 92274688 bytes
totalBlocks = 22528
fork temperature = /* Metadata Zone */
clumpSize = 11534336 bytes
extents = startBlock blockCount % of file
0x148dde 0x5800 100.00 %
22528 allocation blocks in 1 extents total.
22528.00 allocation blocks per extent on an average.
# Attributes File
logicalSize = 0 bytes
# Startup File
logicalSize = 0 bytes