How to best do zillions of little files?

[kentborg at borg.org (Kent Borg)]

On Wed, Oct 02, 2002 at 01:18:26PM -0400, Andy Davidoff wrote:
> I once used the inodes of files as a unique key from which...

This won't be news to Andy, but still one thing to remind anyone who
is considering doing such a thing is that moving the data as files
from one disk to another will not preserve inode numbers.  The file
system issues the inode numbers and another file system will end up
issuing different inode numbers.

One example of this biting is with qmail.  It uses inode numbers to
keep track of something (I forget what) with the result that the spool
directory (ironically, a hashed tree that is designed to hold lots of
files for fast access!) cannot really be moved to another disk,
backedup/restored, etc.

Certainly data can still be moved, but not with common file
manipulation tools.  In the case of qmail there are no utilities
written to move this data short of letting it get mailed.  By putting
your files in inode-sensitive files you won't get such tools for free
the way you would with straight forward, named files.


This approach can make good sense.  I am only warning that you want to
appreciate this consequence before doing it.


-kb