Unix dump/restore tape format - Revision history

Jnc: Avoid redir

2025-04-18T16:42:28Z

Avoid redir

← Older revision		Revision as of 16:42, 18 April 2025
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	The [[Unix]] '''dump''' command makes a full or incremental backup of a single [[disk]] partition to [[magnetic tape]]s or [[file]]s. The corresponding '''restore''' command recovers data from such tapes. The tape format is vaguely documented in various man pages, but not to a detail necessary to fully understand it. This primarily describes the formats used by [[Unix V7]], [[4BSD]], and [[SunOS]] around the 1980s.		The [[UNIX\|Unix]] '''dump''' command makes a full or incremental backup of a single [[disk]] [[partition]] to [[magnetic tape]]s or [[file]]s. The corresponding '''restore''' command recovers data from such tapes. The tape format is vaguely documented in various man pages, but not to a detail necessary to fully understand it. This primarily describes the formats used by [[Unix V7]], [[4BSD]], and [[SunOS]] around the 1980s.

	A dump is logically a series of 1024-byte [[block]]s, grouped ten at a time into tape [[record]]s. There are no tape marks interspersed between records, just the normal double mark and the end of a tape. A block can be a [[header]], or data. Header blocks hold metadata and [[UNIX file system\|inode]] information.		A dump is logically a series of 1024-byte [[block]]s, grouped ten at a time into tape [[record]]s. There are no tape marks interspersed between records, just the normal double mark and the end of a tape. A block can be a [[header]], or data. Header blocks hold metadata and [[UNIX file system\|inode]] information.

Larsbrinkhoff at 05:49, 9 September 2022

2022-09-09T05:49:43Z

← Older revision		Revision as of 05:49, 9 September 2022
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	===TS_TAPE===		===TS_TAPE===

	Header type 1. This header must start all volumes. The Date field must be same on all volumes. The Volume field identifies the individual tape in the dump.		Header type 1. This header must start all volumes. The Date field must be same on all volumes. The Volume field identifies the individual tape in the dump. There are no data blocks.

	===TS_BITS and TS_CLRI===		===TS_BITS and TS_CLRI===
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	===TS_INODE and TS_ADDR===		===TS_INODE and TS_ADDR===

	Header types 2 and 4. TS_INODE stores the inode data from disk. After the header block comes data blocks, as per the Addr array. A one signals a data block is present on tape. A zero indicates a 1024-byte hole in the file. If a volume runs out of space during a run of data blocks, the next volume begins with a TS_TAPE block, and then follows the rest of the data blocks.		Header types 2 and 4. TS_INODE stores the inode data from disk. After the header block comes data blocks, as per the Addr array. An array item of one signals a data block is present on tape. A zero indicates a 1024-byte hole in the file. If a volume runs out of space during a run of data blocks, the next volume begins with a TS_TAPE block, and then follows the rest of the data blocks.

	The Addr field is normally 256 byte at the most. If it can't accommodate a large file, several TS_ADDR may follow. A TS_ADDR header stores the same inode data, but following data blocks are appended to the file.		The Addr field is normally 256 byte at the most. If it can't accommodate a large file, several TS_ADDR may follow. A TS_ADDR header stores the same inode data, but following data blocks are appended to the file.
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	\|}		\|}

	The directory for the new format has variable-length entries. ~~A 0~~ entry length signals the end of the directory.		The directory for the new format has variable-length entries. An entry length of 0 signals the end of the directory.

	{\| class="wikitable"		{\| class="wikitable"
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	===TS_END===		===TS_END===

	Header type 5. This header signals the end of the dump on the last volume. Several TS_END blocks may be written.		Header type 5. This header signals the end of the dump on the last volume. Several TS_END blocks may be written. There are no data blocks.

	[[Category: Tape Formats]]		[[Category: Tape Formats]]
	[[Category: UNIX]]		[[Category: UNIX]]

Larsbrinkhoff: /* TAPE HEADER */

2022-09-09T05:46:46Z

TAPE HEADER

← Older revision		Revision as of 05:46, 9 September 2022
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	\| Addr		\| Addr
	\| 40 bytes		\| 40 bytes
	\| Not present		\| ''Not present''
	\|-		\|-
	\| Atime		\| Atime
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	\|-		\|-
	\| ?		\| ?
	\| Not present		\| ''Not present''
	\| 32 bits		\| 32 bits
	\|-		\|-
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	\|-		\|-
	\| ?		\| ?
	\| Not present		\| ''Not present''
	\| 32 bits		\| 32 bits
	\|-		\|-
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	\|-		\|-
	\| ?		\| ?
	\| Not present		\| ''Not present''
	\| 92 bytes		\| 92 bytes
	\|-		\|-

Larsbrinkhoff: /* TAPE HEADER */ Total inode size.

2022-09-09T05:45:43Z

TAPE HEADER: Total inode size.

← Older revision		Revision as of 05:45, 9 September 2022
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	\| 92 bytes		\| 92 bytes
	\|-		\|-
			! Total
			\| 64 bytes
			\| 128 bytes
	\|}		\|}

Larsbrinkhoff: Or files.

2022-09-09T05:39:41Z

Or files.

← Older revision		Revision as of 05:39, 9 September 2022
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	The [[Unix]] '''dump''' command makes a full or incremental backup of a single [[disk]] partition to [[magnetic tape]]s. The corresponding '''restore''' command recovers data from such tapes. The tape format is vaguely documented in various man pages, but not to a detail necessary to fully understand it. This primarily describes the formats used by [[Unix V7]], [[4BSD]], and [[SunOS]] around the 1980s.		The [[Unix]] '''dump''' command makes a full or incremental backup of a single [[disk]] partition to [[magnetic tape]]s or [[file]]s. The corresponding '''restore''' command recovers data from such tapes. The tape format is vaguely documented in various man pages, but not to a detail necessary to fully understand it. This primarily describes the formats used by [[Unix V7]], [[4BSD]], and [[SunOS]] around the 1980s.

	A dump is logically a series of 1024-byte [[block]]s, grouped ten at a time into tape [[record]]s. There are no tape marks interspersed between records, just the normal double mark and the end of a tape. A block can be a [[header]], or data. Header blocks hold metadata and [[UNIX file system\|inode]] information.		A dump is logically a series of 1024-byte [[block]]s, grouped ten at a time into tape [[record]]s. There are no tape marks interspersed between records, just the normal double mark and the end of a tape. A block can be a [[header]], or data. Header blocks hold metadata and [[UNIX file system\|inode]] information.

Larsbrinkhoff: Some notes.

2022-09-09T05:38:53Z

Some notes.

← Older revision		Revision as of 05:38, 9 September 2022
Line 1:		Line 1:
	The [[Unix]] '''dump''' command makes a full or incremental backup of a single [[disk]] partition to [[magnetic tape]]s. The corresponding '''restore''' command recovers data from such tapes. The tape format is vaguely documented in various man pages, but not to a detail necessary to fully understand it.		The [[Unix]] '''dump''' command makes a full or incremental backup of a single [[disk]] partition to [[magnetic tape]]s. The corresponding '''restore''' command recovers data from such tapes. The tape format is vaguely documented in various man pages, but not to a detail necessary to fully understand it. This primarily describes the formats used by [[Unix V7]], [[4BSD]], and [[SunOS]] around the 1980s.

	A dump is logically a series of 1024-byte [[block]]s, grouped ten at a time into tape [[record]]s. There are no tape marks interspersed between records, just the normal double mark and the end of a tape. A block can be a [[header]], or data. Header blocks hold metadata and [[UNIX file system\|inode]] information.		A dump is logically a series of 1024-byte [[block]]s, grouped ten at a time into tape [[record]]s. There are no tape marks interspersed between records, just the normal double mark and the end of a tape. A block can be a [[header]], or data. Header blocks hold metadata and [[UNIX file system\|inode]] information.
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	The tape format comes in two versions. The first version is for the older [[UNIX file system]], and the second version is for [[BSD Fast File System\|Berkeley's FFS file system]]. On top of that, data can be 16 or 32 bits wide, and big or little endian.		The tape format comes in two versions. The first version is for the older [[UNIX file system]], and the second version is for [[BSD Fast File System\|Berkeley's FFS file system]]. On top of that, data can be 16 or 32 bits wide, and big or little endian.

			Notes:
			* Since dump reads low-level file system information like inode numbers, it's limited to a single partition.
			* If the first volume has been lost, it's likely that directories and filenames can't be recovered.
			* File data blocks may spill over to the next volume, but look out for that TS_TAPE block.

	===TAPE HEADER===		===TAPE HEADER===

Larsbrinkhoff: /* TS_INODE and TS_ADDR */ Data blocks can span across volumes, but there's still a TS_TAPE block first on the next volume.

2022-09-08T19:16:02Z

TS_INODE and TS_ADDR: Data blocks can span across volumes, but there's still a TS_TAPE block first on the next volume.

← Older revision		Revision as of 19:16, 8 September 2022
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	===TS_INODE and TS_ADDR===		===TS_INODE and TS_ADDR===

	Header types 2 and 4. TS_INODE stores the inode data from disk. After the header block comes data blocks, as per the Addr array. A one signals a data block is present on tape. A zero indicates a 1024-byte hole in the file.		Header types 2 and 4. TS_INODE stores the inode data from disk. After the header block comes data blocks, as per the Addr array. A one signals a data block is present on tape. A zero indicates a 1024-byte hole in the file. If a volume runs out of space during a run of data blocks, the next volume begins with a TS_TAPE block, and then follows the rest of the data blocks.

	The Addr field is normally 256 byte at the most. If it can't accommodate a large file, several TS_ADDR may follow. A TS_ADDR header stores the same inode data, but following data blocks are appended to the file.		The Addr field is normally 256 byte at the most. If it can't accommodate a large file, several TS_ADDR may follow. A TS_ADDR header stores the same inode data, but following data blocks are appended to the file.

Larsbrinkhoff: /* TS_INODE and TS_ADDR */ Directory formats.

2022-09-08T13:35:56Z

TS_INODE and TS_ADDR: Directory formats.

@@ Line 148: / Line 148: @@
 Header types 2 and 4.  TS_INODE stores the inode data from disk.  After the header block comes data blocks, as per the Addr array.  A one signals a data block is present on tape.  A zero indicates a 1024-byte hole in the file.
-The Addr field is normally 256 byte at the most.  If it can't accommodate a large file, several TS_ADDR may follow.  TS_ADDR stores the same inode data, but following data blocks are appended to the file.
+The Addr field is normally 256 byte at the most.  If it can't accommodate a large file, several TS_ADDR may follow.  A TS_ADDR header stores the same inode data, but following data blocks are appended to the file.
 ===TS_END===

Larsbrinkhoff: Volume.

2022-09-08T11:15:32Z

Volume.

← Older revision		Revision as of 11:15, 8 September 2022
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	A dump is logically a series of 1024-byte [[block]]s, grouped ten at a time into tape [[record]]s. There are no tape marks interspersed between records, just the normal double mark and the end of a tape. A block can be a [[header]], or data. Header blocks hold metadata and [[UNIX file system\|inode]] information.		A dump is logically a series of 1024-byte [[block]]s, grouped ten at a time into tape [[record]]s. There are no tape marks interspersed between records, just the normal double mark and the end of a tape. A block can be a [[header]], or data. Header blocks hold metadata and [[UNIX file system\|inode]] information.

	Dumps will normally span several tapes. All ~~tapes~~ begin with a '''TS_TAPE''' block. The last ~~tape~~ ends with one or several '''TS_END''' blocks. The first ~~tape~~ will have '''TS_BITS''' and '''TS_CLRI''' blocks after TS_TAPE. The rest of the tape blocks are of type '''TS_INODE''', storing raw inodes as stored on disk, followed by data blocks. In some cases a TS_INODE header can not store all information needed, in which case it can be extended with '''TS_ADDR''' blocks. Normally the first inodes written to tape is the entire directory structure of the whole file system, and file inodes make up the rest of the ~~tapes~~.		Dumps will normally span several tapes, each of which is called a '''volume'''. All volumes begin with a '''TS_TAPE''' block. The last volume ends with one or several '''TS_END''' blocks. The first volume will have '''TS_BITS''' and '''TS_CLRI''' blocks after TS_TAPE. The rest of the tape blocks are of type '''TS_INODE''', storing raw inodes as stored on disk, followed by data blocks. In some cases a TS_INODE header can not store all information needed, in which case it can be extended with '''TS_ADDR''' blocks. Normally the first inodes written to tape is the entire directory structure of the whole file system, and file inodes make up the rest of the volumes.

	The tape format comes in two versions. The first version is for the older [[UNIX file system]], and the second version is for [[BSD Fast File System\|Berkeley's FFS file system]]. On top of that, data can be 16 or 32 bits wide, and big or little endian.		The tape format comes in two versions. The first version is for the older [[UNIX file system]], and the second version is for [[BSD Fast File System\|Berkeley's FFS file system]]. On top of that, data can be 16 or 32 bits wide, and big or little endian.
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	===TS_TAPE===		===TS_TAPE===

	Header type 1. This header must start all ~~tapes~~. The Date field must be same on all ~~tapes~~. The Volume field identifies the individual tape in the dump.		Header type 1. This header must start all volumes. The Date field must be same on all volumes. The Volume field identifies the individual tape in the dump.

	===TS_BITS and TS_CLRI===		===TS_BITS and TS_CLRI===
Line 146:		Line 146:
	===TS_INODE and TS_ADDR===		===TS_INODE and TS_ADDR===

	Header types 2 and 4. TS_INODE stores the inode data from disk. After the header block comes data blocks, as per the Addr ~~field~~. A one signals a data block is present on tape. A zero indicates a hole in the file.		Header types 2 and 4. TS_INODE stores the inode data from disk. After the header block comes data blocks, as per the Addr array. A one signals a data block is present on tape. A zero indicates a 1024-byte hole in the file.

	~~If the TS_INODE~~ Addr field can't accommodate ~~the~~ file, several TS_ADDR may follow. TS_ADDR stores the same inode data, but following data ~~block~~ are appended to the file.		The Addr field is normally 256 byte at the most. If it can't accommodate a large file, several TS_ADDR may follow. TS_ADDR stores the same inode data, but following data blocks are appended to the file.

	===TS_END===		===TS_END===

	Header type 5. This header signals the end of the dump on the last ~~tape~~. Several TS_END blocks may be written.		Header type 5. This header signals the end of the dump on the last volume. Several TS_END blocks may be written.

	[[Category: Tape Formats]]		[[Category: Tape Formats]]
	[[Category: UNIX]]		[[Category: UNIX]]

Larsbrinkhoff: /* TAPE HEADER */ Ddate.

2022-09-08T11:10:54Z

TAPE HEADER: Ddate.

← Older revision		Revision as of 11:10, 8 September 2022
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	\| colspan="2" \| Timestamp		\| colspan="2" \| Timestamp
	\|-		\|-
	\| ~~DDate~~		\| Ddate
	\| Dump from		\| Dump from
	\| 32 bits		\| 32 bits
	\| colspan="2" \| Timestamp		\| colspan="2" \| Timestamp from previous incremental backup, or 0 for full
	\|-		\|-
	\| Volume		\| Volume