F17: trying to diagnose problem with external USB drive

[Mikkel L. Ellertson]

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On 07/18/2012 02:18 PM, M. Fioretti wrote:
> On Wed, Jul 18, 2012 07:54:15 AM -0400, G.Wolfe Woodbury wrote:
>> On 07/18/2012 08:03 AM, M. Fioretti wrote:
>>> rsync -rpvt --delete /photo/ /media/LACIE/photo
>>>
>>> the drives ALWAYS becomes read-only at some point, thus making
rsync fail
>>>
>>> dmesg says (complete output below) that:
>>>
>>> [625087.410234] FAT-fs (sdb1): error, fat_free_clusters:
deleting FAT entry beyond EOF
>>> [625087.410239] FAT-fs (sdb1): Filesystem has been set read-only
>>>
>> Looks to me like there are too many files for the sinple FAT16
>> directory structure on the device.
>
> I understand what you say, but:
>
> the folder that I am backing up contains <25k files total, in lots of
> folders and subfolders, and afaik the max number of files for vfat
> (both 16 and 32) is well above that number
>
> above all, I was doing this backup on two different USB external
> drives of different size (500 and 128 GB), both with enough space to
> host that folder (which is ~110 GB) and both vfat. But there was no
> problem with the bigger drive.
>
> If the number of files is the problem, why would it happen only on the
> smallest drive? Simply because it is smaller, e.g. with less blocks,
> even if the number of files is well below the vfat maximum?
>
> Thanks,
> Marco
>
>
>
If you are trying to put 110 GB on a 128 GB drive, you are probably
running out of room. Run "df -h" when the drive is mounted, and see
how much space the drive has after things like the space used by
formatting the drive, and possible differences in how 1 GB is
figured are taken into account. Then there is all the wasted space
on files that are not exact multiples of the allocation size.
Remember, a 2 byte file still uses up one allocation block. So does
a directory.

Depending on the file system, you can run out of allocation units
before running out of disk space. The fact that it is VFAT does not
tell you anything about the underlying file system. VFAT is a way to
use long file names on a FAT file system. It can be any size FAT
file system. The underlying file system determines how many files
you can have, and the allocation unit size.

- From the error message, it looks like you are running out of
allocation units. The system tried to allocate more FAT entries that
there were on the drive. "deleting FAT entry beyond EOF"

Just for fun, what does "fdisk -l <device>" tell you about the file
system?

Mikkel
- -- 
Do not meddle in the affairs of dragons, for thou art crunchy and
taste good with Ketchup!
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