I was copying files to a directory remote with `git annex copy`.  Out of 114 files, 9 of them failed with no message, just:

    copy data/foo.dat (to usbdrive...) failed
    copy data/bar.dat (to usbdrive...) failed

According to strace:

    31338 mkdir("/media/annex/Zp/9v/SHA256-s1362999320--d650297c8cf8c2dc0575110a52d0c5cc0ff266f294a0599f85796a6b44b23492", 0777) = -1 ENOENT (No such file or directory)
    31338 mkdir("/media/annex/Zp/9v", 0777) = -1 ENOENT (No such file or directory)
    31338 mkdir("/media/annex/Zp", 0777)    = -1 EEXIST (File exists)
    31338 stat("/media/annex/Zp", 0x7f8449f170d0) = -1 ENOENT (No such file or directory)

The filesystem is FAT32 and has weird case semantics.  This was mounted by udisks with its default options:

    /dev/sdb1 on /media/annex type vfat (rw,nosuid,nodev,uhelper=udisks,uid=1000,gid=1000,shortname=mixed,dmask=0077,utf8=1,showexec)

I wonder if the directory remote should use hashDirLower instead of hashDirMixed?

> git-annex intentionally uses the same layout for directory and rsync
> special remotes as it does for the .git/annex directory. As far
> as I know it works ok on (truely) case-insensative filesystems.
> 
> Based on your strace, if you `ls /media/annex/Zp`, you will see
> "No such file or directory", but if you `mkdir /media/annex/Zp` it will
> fail with "File exists". Doesn't make much sense to me.
> 
> The (default) VFAT mount option shortname=mixed causes this behavior.
> With shortname=lower it works ok. --[[Joey]]
> 
>> So, the options for fixing this bug seem to be to fix Linux (which would
>> be a good idea IMHO but I don't really want to go there), or generally
>> convert git-annex to using lowercase for its hashing (which would be a
>> large amount of pain to rewrite all the symlinks in every git repo),
>> or some special hack around this problem. 
>> 
>> I've put in a workaround for the problem in the directory special
>> remote; it will use mixed case but fall-back to lowercase as necessary.
>> 
>> That does leave the case of a bare git repository with annexed content
>> stored on VFAT. More special casing could fix it, but that is, I
>> think, an unusual configuration. Leaving the bug open for that case,
>> and for the even more unlikely configuration of a rsync special remote
>> stored on VFAT. --[[Joey]] 

>>> Bare repositories now use lowercase. rsync is the only remaining
>>> unsupported possibility. --[[Joey]]
>>>> Everything now uses lowercase, with the exception of non-bare
>>>> repos, which cannot be on FAT anyway due to using symlinks. [[done]]
>>>> --[[Joey]]