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>

This include file has the following contents:

#define NTREC   20
#define MLEN    16
#define MSIZ    4096
 #define TS_TAPE 1
#define TS_INODE2
#define TS_BITS 3
#define TS_ADDR 4
#define TS_END  5
#define TS_CLRI 6
#define MAGIC   (int)60011
#define CHECKSUM(int)84446
structspcl
{
intc_type;
time_tc_date;
time_tc_ddate;
intc_volume;
daddr_tc_tapea;
ino_tc_inumber;
intc_magic;
intc_checksum;
structdinodec_dinode;
intc_count;
charc_addr[BSIZE];
} spcl;
 structidates
{
charid_name[16];
charid_incno;
time_tid_ddate;
};

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. 

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 non-zero.  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(1M), restor(1M), fs(5). 

May 16, 1980