git-annex/doc/forum/hashing_objects_directories.mdwn

I'm wondering how easy the addition of hashing to the directories of the objects would be.

Currently a tree directory structure becomes a flat two level tree under the .git/annex/objects directory ([[internals]]).  This, through the 555 mode on the directory prevents the accidental destruction of content, which is _good_.  However file and directory numbers soon add up in there and as such any file-systems with sub directory limitations will quickly realize the limit (certainly quicker than maybe expected).

Suggestion is therefore to change from 

 `.git/annex/objects/SHA1:123456789abcdef0123456789abcdef012345678/SHA1:123456789abcdef0123456789abcdef012345678`

to 

 `.git/annex/objects/SHA1:1/2/3456789abcdef0123456789abcdef012345678/SHA1:123456789abcdef0123456789abcdef012345678`

or anything in between to a paranoid

 `.git/annex/objects/SHA1:123/456/789/abc/def/012/345/678/9ab/cde/f01/234/5678/SHA1:123456789abcdef0123456789abcdef012345678`

Also the use of a colon specifically breaks FAT32 ([[bugs/fat_support]]), must it be a colon or could an extra directory be used? i.e. `.git/annex/objects/SHA1/*/...`

`git annex init` could also create all but the last level directory on initialization. I'm thinking `SHA1/1/1, SHA1/1/2, ..., SHA256/f/f, ..., URL/f/f, ..., WORM/f/f`

> This is done now with a 2-level hash. It also hashes .git-annex/ log
> files which were the worse problem really. Scales to hundreds of millions
> of files with each dir having 1024 or fewer contents. Example:
>
> `me -> .git/annex/objects/71/9t/WORM-s3-m1300247299--me/WORM-s3-m1300247299--me`
>
> --[[Joey]]