dumpseg - print segment information of NILFS2
program is an analysis tool for on-disk logs of a NILFS2 file
system found in device
. It displays the configuration of every log
stored in the segments specified by one or more segment-numbers
term segment here means a contiguous lump of disk blocks giving an allocation
unit of NILFS2 disk space. When device
is omitted, it tries to find an
active NILFS2 file system from /proc/mounts
is a tool for debugging rather than administration. To list a
summary of segments, lssu
(1) is available instead.
- -h, --help
- Display help message and exit.
- -V, --version
- Display version and exit.
shows the configuration of each log with the following fields,
where each field is printed in the style of `` field-name =
- creation time
- Creation date and time of the log.
- Number of file information summaries.
- File information summary. This information starts with the
- Inode number of the file.
- Number of the checkpoint that the blocks included in the
file belong to. For normal writings, this is equal to the latest
checkpoint number. For the writings involved in garbage collection, this
indicates a past checkpoint number.
- Number of blocks of the file written in the log. This
number is a sum of the number of data blocks and B-tree node blocks. The
contents of these blocks are written serially in the payload part of the
log. Only modified or newly created blocks are written to each log.
- Number of data blocks of the file written in the log.
- Then, for each update block in the file, the following
information will follow these headings.
- Virtual block number. Not printed for data blocks of the
Disk Address Translation file (DAT file).
- Block offset number. Not printed for B-tree node blocks
except for the DAT file.
- Level of B-tree node block. Printed only for the DAT
- Block address on the device. This is not an actual
field in the summary but is calculated from the disk address of each
is part of the nilfs-utils package and is available from