mke2fs options for very large filesystems

[Theodore Ts'o]

On Thu, May 19, 2005 at 01:40:34PM -0400, Maurice Volaski wrote:
> Wouldn't -T largefile already be making choices about the default 
> bytes-per-inode?
> 
> How could I make my own determination about what values are most 
> appropriate for -i and -N? My filesystems are generally several 
> hundreds of gigabytes, filled with files that average about one 
> megabyte in size.

Well, "mke2s -i 1048576" will create an inode for every megabyte
(1,048,576 byte) of space on the filesystem.  However, once you create
a filesystem, it's not possible to increase the number of inodes in
that filesystem afterwards.  Also, symbolic links also take up inodes,
as do block and character devices.  So in general you want to
overallocate inodes somewhat.  For example, if you specify "mke2fs -i
524288" then you will be creating twice as many inodes, since you are
asking mke2fs to create an inode for every 512k of space.

						- Ted