.th DUMP V 4/21/86
.sh NAME
dump - incremental dump format
.sh DESCRIPTION
The fsd and fsr programs are used to incrementally dump and restore
KSOS file systems.  The dump format consists of four sections, each of
which is an integral number of 512-byte blocks long: a one block dump
master, the file system's security map, a dump map and, finally, the
jnodes (analogous to UNIX inodes) and data blocks for each file dumped.
The complete dump is written out as one long record composed of logical
512-byte blocks.
.P
The first block has the following structure:
.sp
dump_master = RECORD
.br
   mount : mountItem       (* fs mount item - 102 bytes *)
.br
   from_date : timeStamp;  (* incremental dump date *)
.br
   dump_date : timeStamp;  (* date this dump was taken *)
.br
   size : cardinal32;      (* blocks used on save device *)
.br
   secmap_size : cardinal; (* security map size (blocks) *)
.br
   filler : ARRAY 1:DM_FILLSZ OF char; (* filler *)
.br
   checksum : cardinal;    (* block checksum *)
.br
END;
.sp
.P
The security map is a copy of the security map database for the KSOS
system on which the file system resides.  Its size is specified by
secmap_size and is normally 8 blocks long.
.P
The dump map contains one boolean element for each slot in the system
space of the file system.  It indicates which file system slots contain
jnodes.  It is essentially a copy of the file system allocation map
minus references to indirect items.  Its size (in blocks) is equal to
(total system slots)/(512*8 bits per block) rounded up.  The rest of
the output is made up of the data blocks for each dumped file.  Each set
of data blocks is immediately preceded by a block containing the jnode
for the file.  These jnode blocks each contain a dump block number and
a checksum.  The final block on the output has a dump block number of 0.
.sh "SEE ALSO"
fsd (VIII), fsr (VIII)
.sh NOTES
A dump can be made to tape or to an extent on a disk.  See IOFform.mod
(generally found in /ksb/kernel/KIO/IOF) for a description of jnode
format.
