questions about File System Switch

[Roger Warner]

In article <352 at siswat.UUCP> buck at siswat.UUCP (A. Lester Buck) writes:
>I have seen a number of postings which have mentioned the
>File System Switch (FSS), and Bach has some general sections
>on file system abstractions.  Is FSS fully documented in
>some AT&T manual?  What release of System V introduced FSS?
>Is it always there, or is it a vendor option that can be
>left out?  (I only have S5R2 experience.)

FSS is not documented in any external AT&T manual.  
It first appeared commercially in 5.3.0.
And it is integral to the execution of 5.3.0.

>
>Is adding a new filesystem on the same level as adding a
>device driver to the kernel? For example, can a binary site
>use some type of link kit to add filesystem routines without
>source code?

We don' 3blink-boot so thats really a system specific issue.  Would you want 
to do it at home?  I've worked on a port of NFS and FFS into the 5.3.0 kernel
and would not suggest it.  The problems are not so much related to to the FFS
as the buffer cache.  The buffer cache really, really wants you to use 1K
buffers, which is not always ideal for non S51K file systems.

BSD uses the VFS which is more more well suited for adding new FS types.  The 
buffer cache routines are part of the BSD VFS.  Unfortunately then you have
to deal w/the rest of the BSD kernel... ;-).

---
roger warner
uunet!ingr!roger
roger at ingr.com


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