1DUMPSEG(8) System Manager's Manual DUMPSEG(8)
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6 dumpseg - print segment information of NILFS2
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9 dumpseg [-hV]
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11 dumpseg [device] segment-number ...
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14 The dumpseg program is an analysis tool for on-disk logs of a NILFS2
15 file system found in device. It displays the configuration of every
16 log stored in the segments specified by one or more segment-numbers.
17 The term segment here means a contiguous lump of disk blocks giving an
18 allocation unit of NILFS2 disk space. When device is omitted, it tries
19 to find an active NILFS2 file system from /proc/mounts.
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21 dumpseg is a tool for debugging rather than administration. To list a
22 summary of segments, lssu(1) is available instead.
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25 -h, --help
26 Display help message and exit.
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28 -V, --version
29 Display version and exit.
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32 dumpseg shows the configuration of each log with the following fields,
33 where each field is printed in the style of ``field-name = value''.
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35 creation time
36 Creation date and time of the log.
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38 nfinfo Number of file information summaries.
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40 finfo File information summary. This information starts with the fol‐
41 lowing fields:
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43 ino Inode number of the file.
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45 cno Number of the checkpoint that the blocks included in the
46 file belong to. For normal writings, this is equal to
47 the latest checkpoint number. For the writings involved
48 in garbage collection, this indicates a past checkpoint
49 number.
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51 nblocks
52 Number of blocks of the file written in the log. This
53 number is a sum of the number of data blocks and B-tree
54 node blocks. The contents of these blocks are written
55 serially in the payload part of the log. Only modified
56 or newly created blocks are written to each log.
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58 ndatblk
59 Number of data blocks of the file written in the log.
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61 Then, for each update block in the file, the following informa‐
62 tion will follow these headings.
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64 vblocknr
65 Virtual block number. Not printed for data blocks of the
66 Disk Address Translation file (DAT file).
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68 blkoff Block offset number. Not printed for B-tree node blocks
69 except for the DAT file.
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71 level Level of B-tree node block. Printed only for the DAT
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74 blocknr
75 Block address on the device. This is not an actual field
76 in the summary but is calculated from the disk address of
77 each log.
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80 Koji Sato
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83 dumpseg is part of the nilfs-utils package and is available from
84 https://nilfs.sourceforge.io.
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87 nilfs(8), lssu(1).
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91nilfs-utils version 2.2 Apr 2014 DUMPSEG(8)