4BSD file system structure

[Greg Hinton]

I'm hoping some of you Wizards can help me decipher the structure
of the 4BSD file system.

First, what is the layout of the zero'th cylinder group?  According
to <sys/fs.h>, BBLOCK & SBLOCK are "absolute disk addresses".  Is
that CSRG's way of saying "sector numbers"?  Does the zero'th
cylinder group contain the usual complement of cg block, inode blocks
and data blocks?  If so, doesn't the presence of the boot block
throw things off?

Second, how does the on-disk inode (struct dinode in <sys/inode.h>)
indicate that the last block in a file is a fragment?

Thanks in advance for your help.

-- 
Greg Hinton
DOMAIN: hinton at netcom.uucp
UUCP: uunet!apple!netcom!hinton