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I have a web-site that I'm checking for performance issues and bugs, and i came across a caching code that caches thousands of files into one single directory.

I understand that this is not good and that I/O will degrade and i also heard about potential inode problem.

And i know how to fix the caching code, but the thing is that at this point fixing would be very expensive.

The question: What is the worst case scenario if i live it like it is right now? How will happen to the website? (right now this one single cache directory has 400K files)

I'm new to Ubuntu. And i understand that this is might be an off-topic. But i think this is a "system" question and it does not belong to the 'programming' part of the stackoverflow.


UPDATE: The file system is UFS

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I have. I think i will post this on webmasters as well. Thank you :) – rinchik Jan 31 '13 at 15:33
Important: what is the filesystem ext3? ext4? fat? :) – Rinzwind Jan 31 '13 at 15:37
The files system is ufs :) Will update my post shortly – rinchik Jan 31 '13 at 15:50
up vote 0 down vote accepted

UFS works with inodes so the maximum number of files depends on the inode to space ratio that has been set. And that is a lot... a lot more than 400k.

2 problems:

  • Creating new files will take more and more time.

  • You will also run into other problems: ls will error out with Argument list too long. since it will expand all the files (ls -l * turns into ls -l file1 file2 file3 file4 etc etc. Same goes for rm and some other commands.

I know you will not like it but ... it IS best to use sub directories. Yes, can be a hell of a lot of work but you are bound to end up having to do it anyways. Better be prepared now while you have the time than after the server crashed.

Alternative: - analyse if you can drop some files and not cache them.

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