SYS V - What is Inode 1 ?

[Frank Peters]

In article <1991Jan19.123830.8859 at micromuse.co.uk> peter at micromuse (Peter Galbavy) writes:
   For a while now I have been trying to find out - for no good reason -
   what inode 1 is reserved for in ATT SYSV. Whether the same is true for
   other UN*X's I do not know, but whatever V.2 or V.3 release I have
   seen, the root directory of a file system is always (as far as I have
   seen) inode 2.

   I remember finding a quote along the lines of 'inode 1 is reserved for
   future use' in a manual somewhere.

   Anyone out there know the reason ? And is it a good one ?


>From the inode man page for SunOS 4.1:

The root inode is the root of the file system.  Inode 0 can-
not  be used for normal purposes and historically bad blocks
were linked to inode 1, thus the root inode is 2 (inode 1 is
no longer used for this purpose, however numerous dump tapes
make this  assumption,  so  we  are  stuck  with  it).   The
lost+found  directory is given the next available inode when
it is initially created by mkfs(8).

Is backwards compatibility a good reason?  Depends upon whether you
need it I guess.

FWP
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