[clug] max open files

Amitay Isaacs amitay at gmail.com
Thu Jan 14 19:06:06 MST 2010

Hi Adrian,

On Fri, Jan 15, 2010 at 11:53 AM, Adrian <adrian.blake at ieee.org> wrote:

> CLUGers
> Is there a limit on the number of files open at a single instant or a
> parameter that limits this?

There are two settings. A user limit and kernel limit.

The user limit is implemented by a shell. Typically it is around 1024 file
descriptors per
process. (This includes open files, open sockets, etc.) You can increase
that limit by

However, there is an absolute max number of open files defined by the
kernel. It is
1048576 file descriptors.

How does having a large number of open files limit performance?
> What files system are best suited to have a large number of files open at a
> single instant without serious decrease in performance?

The performance of file system may not be directly related to the number of
open files
unless you are reading and/or writing. The number of open files is a
parameter defined
in the kernel and is independent of the type of the file system.

> Adrian

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