virt-df - Online in the Cloud

PROGRAM:

NAME

virt-df - Display free space on virtual filesystems

SYNOPSIS

All guests:

virt-df [--options]

Single guest:

virt-df [--options] -d domname

virt-df [--options] -a disk.img [-a disk.img ...]

Old style:

virt-df [--options] domname

virt-df [--options] disk.img [disk.img ...]

DESCRIPTION

"virt-df" is a command line tool to display free space on virtual machine filesystems.
Unlike other tools, it doesn't just display the size of disk allocated to a virtual
machine, but can look inside disk images to see how much space is really being used.

If used without any -a or -d arguments, "virt-df" checks with libvirt to get a list of all
active and inactive guests, and performs a "df"-type operation on each one in turn,
printing out the results.

If any -a or -d arguments are specified, "virt-df" performs a "df"-type operation on
either the single named libvirt domain, or on the disk image(s) listed on the command line
(which must all belong to a single VM). In this mode (with arguments), "virt-df" will
only work for a single guest. If you want to run on multiple guests, then you have to
invoke "virt-df" multiple times.

Use the --csv option to get a format which can be easily parsed by other programs. Other
options are similar to the standard df(1) command.

EXAMPLES

Show disk usage for a single libvirt guest called "F14x64". Make the output human-
readable:

# virt-df -d F14x64 -h
Filesystem Size Used Available Use%
F14x64:/dev/sda1 484M 66M 393M 14%
F14x64:/dev/vg_f13x64/lv_root 7.4G 3.4G 4.0G 46%

Show disk usage for a disk image file called test.img:

$ virt-df -a test1.img
Filesystem 1K-blocks Used Available Use%
test1.img:/dev/sda1 99099 1551 92432 2%

If a single guest has multiple disks, use the -a option repeatedly. A plus sign ("+") is
displayed for each additional disk. Note: Do not do this with unrelated guest disks.

$ virt-df -a Win7x32TwoDisks-a -a Win7x32TwoDisks-b
Filesystem 1K-blocks Used Available Use%
Win7x32TwoDisks-a+:/dev/sda1 102396 24712 77684 25%
Win7x32TwoDisks-a+:/dev/sda2 12478460 7403416 5075044 60%
Win7x32TwoDisks-a+:/dev/sdb1 521212 55728 465484 11%

OPTIONS

--help
Display brief help.

-a file
--add file
Add file which should be a disk image from a virtual machine. If the virtual machine
has multiple block devices, you must supply all of them with separate -a options.

The format of the disk image is auto-detected. To override this and force a
particular format use the --format=.. option.

-a URI
--add URI
Add a remote disk. See "ADDING REMOTE STORAGE" in guestfish(1).

-c URI
--connect URI
If using libvirt, connect to the given URI. If omitted, then we connect to the
default libvirt hypervisor.

If you specify guest block devices directly (-a), then libvirt is not used at all.

--csv
Write out the results in CSV format (comma-separated values). This format can be
imported easily into databases and spreadsheets, but read "NOTE ABOUT CSV FORMAT"
below.

-d guest
--domain guest
Add all the disks from the named libvirt guest. Domain UUIDs can be used instead of
names.

--format=raw|qcow2|..
--format
The default for the -a option is to auto-detect the format of the disk image. Using
this forces the disk format for -a options which follow on the command line. Using
--format with no argument switches back to auto-detection for subsequent -a options.

For example:

virt-df --format=raw -a disk.img

forces raw format (no auto-detection) for disk.img.

virt-df --format=raw -a disk.img --format -a another.img

forces raw format (no auto-detection) for disk.img and reverts to auto-detection for
another.img.

If you have untrusted raw-format guest disk images, you should use this option to
specify the disk format. This avoids a possible security problem with malicious
guests (CVE-2010-3851).

-h
--human-readable
Print sizes in human-readable format.

You are not allowed to use -h and --csv at the same time.

-i
--inodes
Print inodes instead of blocks.

--one-per-guest
Since libguestfs 1.22, this is the default. This option does nothing and is left here
for backwards compatibility with older scripts.

-P nr_threads
Since libguestfs 1.22, virt-df is multithreaded and examines guests in parallel. By
default the number of threads to use is chosen based on the amount of free memory
available at the time that virt-df is started. You can force virt-df to use at most
"nr_threads" by using the -P option.

Note that -P 0 means to autodetect, and -P 1 means to use a single thread.

--uuid
Print UUIDs instead of names. This is useful for following a guest even when the
guest is migrated or renamed, or when two guests happen to have the same name.

Note that only domains that we fetch from libvirt come with UUIDs. For disk images,
we still print the disk image name even when this option is specified.

-v
--verbose
Enable verbose messages for debugging.

-V
--version
Display version number and exit.

-x Enable tracing of libguestfs API calls.

STATVFS NUMBERS

"virt-df" (and df(1)) get information by issuing a statvfs(3) system call. You can get
the same information directly, either from the host (using libguestfs) or inside the
guest:

From the host
Run this command:

guestfish --ro -d GuestName -i statvfs /

(change / to see stats for other filesystems).

From inside the guest
Run this command:

python -c 'import os; s = os.statvfs ("/"); print s'

(change / to see stats for other filesystems).

NOTE ABOUT CSV FORMAT

Comma-separated values (CSV) is a deceptive format. It seems like it should be easy to
parse, but it is definitely not easy to parse.

Myth: Just split fields at commas. Reality: This does not work reliably. This example
has two columns:

"foo,bar",baz

Myth: Read the file one line at a time. Reality: This does not work reliably. This
example has one row:

"foo
bar",baz

For shell scripts, use "csvtool" (http://merjis.com/developers/csv also packaged in major
Linux distributions).

For other languages, use a CSV processing library (eg. "Text::CSV" for Perl or Python's
built-in csv library).

Most spreadsheets and databases can import CSV directly.

EXIT STATUS

This program returns 0 if successful, or non-zero if there was an error.

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