DUMP(F) XENIX System V DUMP(F)
Name
dump - Incremental dump tape format.
Description
The dump and restor commands are used to write and read
incremental dump magnetic tapes.
The dump tape consists of a header record, some bit mask
records, a group of records describing file system
directories, a group of records describing file system
files, and some records describing a second bit mask.
The header record and the first record of each description
have the format described by the structure included by:
#include <dumprestor.h>
Fields in the dumprestor structure are described below.
NTREC is the number of 512 byte blocks in a physical tape
record. MLEN is the number of bits in a bit map word. MSIZ
is the number of bit map words.
The TS_ entries are used in the c_type field to indicate
what sort of header this is. The types and their meanings
are as follows:
TS_TYPE Tape volume label.
TS_INODE A file or directory follows. The c_dinode field
is a copy of the disk inode and contains bits
telling what sort of file this is.
TS_BITS A bit mask follows. This bit mask has a one-bit
for each inode that was dumped.
TS_ADDR A subblock to a file (TS_INODE). See the
description of c_count below.
TS_END End of tape record.
TS_CLRI A bit mask follows. This bit mask contains a
one-bit for all inodes that were empty on the
file system when dumped.
MAGIC All header blocks have this number in c_magic.
CHECKSUM Header blocks checksum to this value.
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DUMP(F) XENIX System V DUMP(F)
The fields of the header structure are as follows:
c_type The type of the header.
c_date The date the dump was taken.
c_ddate The date the file system was dumped from.
c_volume The current volume number of the dump.
c_tapea The current block number of this record. This
is counting 512 byte blocks.
c_inumber The number of the inode being dumped if this is
of type TS_INODE.
c_magic This contains the value MAGIC above, truncated
as needed.
c_checksum This contains whatever value is needed to make
the block sum to CHECKSUM.
c_dinode This is a copy of the inode as it appears on
the file system.
c_count This is the count of characters following that
describe the file. A character is zero if the
block associated with that character was not
present on the file system, otherwise the
character is nonzero. If the block was not
present on the file system no block was dumped
and it is replaced as a hole in the file. If
there is not sufficient space in this block to
describe all of the blocks in a file, TS_ADDR
blocks will be scattered through the file, each
one picking up where the last left off.
c_addr This is the array of characters that is used as
described above.
Each volume except the last ends with a tapemark (read as an
end of file). The last volume ends with a TS_END block and
then the tapemark.
The structure idates describes an entry of the file where
dump history is kept.
See Also
dump(C), restor(C), filesystem(F)
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