Provided by: vmfs-tools_0.2.5-1build1_amd64 
NAME
debugvmfs - VMFS file system debugger
SYNOPSIS
debugvmfs VOLUME... COMMAND [ OPTIONS ]
DESCRIPTION
The debugvmfs program allows to display various informations about VMFS file systems, and
to access data within the file systems.
The VOLUME to be opened can be either a block device or an image file. When the VMFS
spreads accross several extents, all extents must be given.
Please note that most commands are still likely to change in future versions.
SPECIFYING FILES
Some commands take a filespec as an argument. A filespec may take either of the following
forms:
• A path name, relative to the root of the filesystem if it starts with '/', or relative
to the current working directory otherwise (interactive mode only).
• An inode number, enclosed between angle brackets, e.g. '<4>', '<0x1400004>'
COMMANDS
cat filespec [ ... ]
Outputs the content of the given files from the VMFS.
ls [ -l ] filespec
Lists files contained at the given location within the VMFS.
With -l, gives some more information, much like the output from ls(1) when given the
-l option.
truncate filespec length
Truncate the file to the specified length. R/W support must be enabled.
chmod filespec mode
Change file permissions to the given mode.
df
Outputs information about file system size.
get_file_block filespec position
Get file block corresponding to position in the specified file.
check_vol_bitmaps
Checks volume bitmaps consistency.
show_heartbeats
Outputs active heartbeats on the file system.
read_block block_id [ ... ]
Outputs content within the specified block_id in binary
get_block_status block_id
Get status (allocated or free) of the specified block_id.
alloc_block_fixed block_id
Allocate the specified block_id. R/W support must be enabled.
alloc_block block_type
Allocate a block of the specified type. R/W support must be enabled.
Allowed block types are: 1 (File Block), 2 (Sub-Block), 3 (Pointer Block) and 4 (File
Descriptor / Inode).
free_block block_id
Free the specified block_id. R/W support must be enabled.
Warning: can cause damage since no heartbeat is used at this time and a block used by
a file can be freed.
show
Display value(s) of the given variable. See the VARIABLES section for more details.
When no variable is given, it lists the top-level properties.
shell
Starts an interactive session. All of the above commands can be executed from within
the interactive session.
The current working directory can be changed with the cd command, followed by a
filespec.
The following output redirections are supported within the shell:
• cmd > output
Puts the output of cmd in the output file.
• cmd >> output
Appends the output of cmd to the output file.
• cmd | external command
Sends the output of cmd to the input of external command. The external command
itself can contain output redirection.
Examples:
• read_block 0x00000681 | less
• cat /.fdc.sf | hexdump -C
• cat /.fdc.sf | hexdump -C > /tmp/fdc.hex
• cat /.fdc.sf | hexdump -C | less
VARIABLES
Variables in debugvmfs represent structures on the filesystem. The currently supported
top-level variables are the following:
• vol_version
• version
• label
• mode
• uuid
• ctime
• block_size
• subblock_size
• fdc_header_size
• fdc_bitmap_count
• fbb
• fdc
• pbc
• sbc
• fs
• lvm
• blkid[blk]
• dirent["path"]
• inode["filespec"]
The vol_version, version, label, mode, uuid, ctime, block_size, subblock_size,
fdc_header_size, and fdc_bitmap_count properties are low-level information about the
filesystem.
The fbb, fdc, pbc and sbc variables are bitmaps. Running them through the show command
will display all the bitmaps header fields. Each of these fields can also be displayed
individually:
• bitmap.items_per_bitmap_entry
• bitmap.bmp_entries_per_area
• bitmap.hdr_size
• bitmap.data_size
• bitmap.area_size
• bitmap.area_count
• bitmap.total_items
• bitmap.used_items
• bitmap.free_items
• bitmap.entry[n]
e.g. to display the data size of the fdc bitmap, type show fdc.data_size.
Each bitmap.entry[n] (where 0 ≤ n < bitmap.bmp_entries_per_area * bitmap.area_count)
contains information about each entry in the bitmap. The available fields are:
• bitmap.entry[n].id
• bitmap.entry[n].total
• bitmap.entry[n].free
• bitmap.entry[n].ffree
• bitmap.entry[n].mdh
• bitmap.entry[n].item[m]
The bitmap.entry[n].mdh is a metadata header. See further below for more details about
metadata headers.
Each bitmap.entry[n].item[m] (where 0 ≤ m < bitmap.items_per_bitmap_entry) contains
information about a given item in the given entry. The available fields are:
• bitmap.entry[n].item[m].used
• bitmap.entry[n].item[m].dump
The pbc bitmap has an additional field:
• pbc.entry[n].item[m].blocks
The lvm variable contains low-level information about the physical and logical volumes.
The available fields are:
• lvm.uuid
• lvm.size
• lvm.blocks
• lvm.num_extents
• lvm.extent[n]
Each lvm.extent[n] (where 0 ≤ n < lvm.num_extents) contains low-level information about
the physical volumes. The available fields are:
• lvm.extent[n].device
• lvm.extent[n].uuid
• lvm.extent[n].lun
• lvm.extent[n].version
• lvm.extent[n].name
• lvm.extent[n].size
• lvm.extent[n].num_segments
• lvm.extent[n].first_segment
• lvm.extent[n].last_segment
Each blkid[blk] (where blk is a block id) contains information on the given block id. The
available fields are:
• blkid[blk].item
• blkid[blk].flags
Each dirent[path] (where path is a path relative to the current directory in the shell or
/ outside the shell) contains information on the directory entry corresponding to the
given path. The available fields are:
• dirent["path"].type
• dirent["path"].block_id
• dirent["path"].record_id
• dirent["path"].name
Each inode[filespec] contains information on the inode corresponding to the given
filespec. The available fields are:
• inode["filespec"].id
• inode["filespec"].id2
• inode["filespec"].nlink
• inode["filespec"].type
• inode["filespec"].flags
• inode["filespec"].size
• inode["filespec"].blk_size
• inode["filespec"].blk_count
• inode["filespec"].uid
• inode["filespec"].gid
• inode["filespec"].mode
• inode["filespec"].zla
• inode["filespec"].tbz
• inode["filespec"].cow
• inode["filespec"].atime
• inode["filespec"].mtime
• inode["filespec"].ctime
• inode["filespec"].rdm_id
• inode["filespec"].mdh
• inode["filespec"].blocks
Metadata headers are being used in several places, such as bitmap.entry[n].mdh and
inode["filespec"].mdh. They mostly contain information about clustered accesses to
metadata on the filesystem. The available fields are:
• mdh.magic
• mdh.pos
• mdh.hb_pos
• mdh.hb_lock
• mdh.hb_uuid
• mdh.hb_seq
• mdh.obj_seq
• mdh.mtime
Variable values can also be used in expressions using square brackets to use the variable
value as an index. For example:
• blkid[inode["filespec"].id]
Enclosing a variable name with parentheses will use that variable value as a variable
name. For example:
• (blkid[blk].item).status
AUTHORS
Christophe Fillot <cf@utc.fr[1]>, Mike Hommey <mh@glandium.org[2]>
SEE ALSO
vmfs-fuse(8)
NOTES
1. cf@utc.fr
mailto:cf@utc.fr
2. mh@glandium.org
mailto:mh@glandium.org
0.0.0.0. 04/03/2018 DEBUGVMFS(8)