[GLLUG] Ext2 recovery

[Brad Fears]

'e2fsck /dev/hdc4' worked, although I was sweating bullets while it 
prompted me to "fix" and "clear" things... :)  On my home machine, it 
recognized the zip as hdb, but would not allow me to run the e2fsck 
command on the partition itself.  I don't know why it worked on my other 
machine, but I'm not complaining!

In the end, my files ended up in a lost+found directory, but at least I 
have them.  Thanks.

--Brad Fears

Matt Graham wrote:
> On Sunday 08 September 2002 23:09, after a long battle with technology, 
> Brad Fears wrote:
> 
>>I somehow managed to corrupt my ext2-formatted zip disk while trying
>>to access it in OS X.  The machine claimed it contained no data,
>>which was when I realized it was formatted ext2.
>>
>>Then I try to mount it back on my linux machine, and it suddenly
>>thinks the partition is vfat.  Thanks, OS X.
>>
>>I tried running 'e2fsck -b 8193 /dev/hdb', but it complains " Attempt
>>to read block from filesystem resulted in short read while trying to
>>open /dev/hdb.  Could this be a zero-length partition?"  I also tried
>>the same command with other superblock backups (24577, 40961, 57345,
>>73729), but none worked.
> 
> 
> First, ZIP disks are always partitioned, so /dev/hdX is not right.  You 
> want to e2fsck /dev/hdX4, most likely.  Second, ext2 filesystems made 
> using versions of mke2fs since about 2000 have always been made with 
> the "sparse superblock" feature turned on.  That means the backup 
> superblocks are arranged differently and there are fewer of them.  The 
> e2fsck maintainers never bothered to switch the "try -b 8193" message 
> to what's currently correct, "try -b 32768".
> 
> Having ext2 filesystems on removable media is not a good idea except in 
> special circumstances.  UIDs, GIDs, and file permissions that are 
> correct on one machine will not be correct on another machine.  ext2 
> has more overhead than FAT16, not good for limited-space things like 
> ZIP disks.  Only Linux can handle ext2 filesystems natively, making 
> ext2 removable media less useful for data exchange.  And as you found 
> out, some OSes will attempt to "fix" removable media that don't conform 
> to the de facto standards....
>