Unix dump/restore tape format - Revision history

Jnc: Avoid redir

2025-04-18T16:42:28Z

Avoid redir

Larsbrinkhoff at 05:49, 9 September 2022

2022-09-09T05:49:43Z

Larsbrinkhoff: /* TAPE HEADER */

2022-09-09T05:46:46Z

‎TAPE HEADER

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

2022-09-09T05:45:43Z

‎TAPE HEADER: Total inode size.

Larsbrinkhoff: Or files.

2022-09-09T05:39:41Z

Or files.

Larsbrinkhoff: Some notes.

2022-09-09T05:38:53Z

Some notes.

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.

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

2022-09-08T13:35:56Z

‎TS_INODE and TS_ADDR: Directory formats.

Larsbrinkhoff: Volume.

2022-09-08T11:15:32Z

Volume.

Larsbrinkhoff: /* TAPE HEADER */ Ddate.

2022-09-08T11:10:54Z

‎TAPE HEADER: Ddate.

← Older revision		Revision as of 16:42, 18 April 2025
Line 1:		Line 1:
−	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.

@@ Line 146: / Line 146: @@
 ===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===
@@ Line 154: / Line 154: @@
 ===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.
@@ Line 174: / Line 174: @@
 |}
-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"
@@ Line 196: / Line 196: @@
 ===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: UNIX]]

@@ Line 113: / Line 113: @@
 | Addr
 | 40 bytes
-| Not present
+| ''Not present''
 |-
 | Atime
@@ Line 120: / Line 120: @@
 |-
 | ?
-| Not present
+| ''Not present''
 | 32 bits
 |-
@@ Line 128: / Line 128: @@
 |-
 | ?
-| Not present
+| ''Not present''
 | 32 bits
 |-
@@ Line 136: / Line 136: @@
 |-
 | ?
-| Not present
+| ''Not present''
 | 92 bytes
 |-

@@ Line 139: / Line 139: @@
 | 92 bytes
 |-
 |}

← Older revision		Revision as of 05:39, 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. 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.

@@ 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.
@@ Line 6: / Line 6: @@
 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.
 ===TAPE HEADER===

@@ Line 32: / Line 32: @@
 | colspan="2" | Timestamp
 |-
-| DDate
+| Ddate
 | Dump from
 | 32 bits
-| colspan="2" | Timestamp
+| colspan="2" | Timestamp from previous incremental backup, or 0 for full
 |-
 | Volume