[CentOS] inquiry about limitation of file system

Sat Nov 3 15:35:36 UTC 2018
Jonathan Billings <billings at negate.org>

On Nov 3, 2018, at 04:16, yf chu <cyflhn at 163.com> wrote:
> Thank you for your hint.
> I really mean I am planning to  store  millions of files on the file system.
> Then may I ask that what is the maximum number of files which could be stored in one directory without affecting the performance of web server?

There are hard limits in each file system.

 For ext4, there is no per-directory limit, but there is an upper limit of total files (inodes really) per file system: 2^32 - 1  (4,294,967,295). XFS also has no per-directory limit, and a 2^64 limit of inodes. (18,446,744,073,709,551,616)

If you are using ext2 or 3 I think the limit per directory is around 10,000, and you start seeing heavy performance issues beyond that. Don’t use them. 

Now, filesystem limits aside, software that try to read those directories with huge numbers of files are going to have performance issues. I/O operations, memory limitations and time are going to be bottlenecks to web operations. 

You really need to reconsider how you want to serve these pages. 
Jonathan Billings