Directory structure for photo uploading?

[forzagrifo]

This might not be a question for PHP per se but here it goes:

I'm developing a site that will have lots of photos (perhaps in the millions, both original-sized and thumbnails) uploaded by users.

What is the best practice in structuring the directories, taking into consideration the fact that there is a maximum number of files permitted in one single directory?

I've seen a lot of large sites like facebook that use very long directories such as "v108/246/65/832432433/n34323252353_23432434_3453.jpg". Is the massive numbers of image uploads the sole reason why there are so many levels of directories, or are there other purposes? I'm wondering if I need to mimic that and have many levels of directories.

And how do I detect when I should create a new directory if the existing directory is full? Do I check for the directory size or number of files in that directory every time a new photo is uploaded, and if the dir is full I create a new dir and put the photo there? Or is there a better way of doing it?

Any advice would be appreciated.

[rulian]

well, they probably use not just directories but variables in the URL thanks to apache and mod rewrites so you can judge how they are storing things by the URL

Depending on your server and it's operating system, different file structures handle file management differently, some only allow 255 subfolders in any give directory, others might have different restrictions.

I personally think it's a bad idea of the user's action to determine file / directory / db strucuture, ever, simplly because you lose control of certain elements.

You could for example, put them into one or just a few folders, add unique user names instance name and image name to the uploaded image name,
if your program names images lets say with 6 random numbers, then a folder an onlly have 999,999 images.
However, if you add user id's to that imagery, and each user id can be up to 6 integers long, then each one can have 999,999 images

2020_483828.jpg
if you have it simply set to 21 characters, 10 for the user, 10 for the images, the total number of images you can safely have without overriding in any folder is 9,999,999,999 x 9,999,999,999 which should give you plently of room.

Whether your OS can handle that many files is another story

[Weedpacket]

But note that many filesystems have performance problems if directories have too many files in them. Thousands of files in a single directory is typically not a great idea.

[forzagrifo]

Thx for the feedback guys. I think I'm going to go with the year/month/day format.