virt-make-fs(1) tar アーカイブまたはファイルからファイルシステムの作成


virt-make-fs [--options] input.tar output.img
virt-make-fs [--options] input.tar.gz output.img
virt-make-fs [--options] directory output.img


Virt-make-fs is a command line tool for creating a filesystem from a tar archive or some files in a directory. It is similar to tools like mkisofs(1), genisoimage(1) and mksquashfs(1). Unlike those tools, it can create common filesystem types like ext2/3 or NTFS, which can be useful if you want to attach these filesystems to existing virtual machines (eg. to import large amounts of read-only data to a VM).

To create blank disks, use virt-format(1). To create complex layouts, use guestfish(1).


 virt-make-fs input output.img

where "input" is either a directory containing files that you want to add, or a tar archive (either uncompressed tar or gzip-compressed tar); and output.img is a disk image. The input type is detected automatically. The output disk image defaults to a raw ext2 sparse image unless you specify extra flags (see ``OPTIONS'' below).


The default filesystem type is "ext2". Just about any filesystem type that libguestfs supports can be used (but not read-only formats like ISO9660). Here are some of the more common choices:
Note that ext3 filesystems contain a journal, typically 1-32 MB in size. If you are not going to use the filesystem in a way that requires the journal, then this is just wasted overhead.
ntfs または vfat
Useful if exporting data to a Windows guest.
Lower overhead than "ext2", but certain limitations on filename length and total filesystem size.

 virt-make-fs --type=minix input minixfs.img


Optionally virt-make-fs can add a partition table to the output disk.

Adding a partition can make the disk image more compatible with certain virtualized operating systems which don't expect to see a filesystem directly located on a block device (Linux doesn't care and will happily handle both types).

On the other hand, if you have a partition table then the output image is no longer a straight filesystem. For example you cannot run fsck(8) directly on a partitioned disk image. (However libguestfs tools such as guestfish(1) and virt-resize(1) can still be used).

MBR パーティションを追加します:

 virt-make-fs --partition -- input disk.img

If the output disk image could be terabyte-sized or larger, it's better to use an EFI/GPT-compatible partition table:

 virt-make-fs --partition=gpt --size=+4T --format=qcow2 input disk.img


Unlike formats such as tar and squashfs, a filesystem does not ``just fit'' the files that it contains, but might have extra space. Depending on how you are going to use the output, you might think this extra space is wasted and want to minimize it, or you might want to leave space so that more files can be added later. Virt-make-fs defaults to minimizing the extra space, but you can use the --size flag to leave space in the filesystem if you want it.

An alternative way to leave extra space but not make the output image any bigger is to use an alternative disk image format (instead of the default ``raw'' format). Using --format=qcow2 will use the native qemu/KVM qcow2 image format (check your hypervisor supports this before using it). This allows you to choose a large --size but the extra space won't actually be allocated in the image until you try to store something in it.

Don't forget that you can also use local commands including resize2fs(8) and virt-resize(1) to resize existing filesystems, or rerun virt-make-fs to build another image from scratch.

 virt-make-fs --format=qcow2 --size=+200M input output.img



今のところ、容量 (1440K)、パーティション形式 (MBR) およびファイルシステム形式 (VFAT) が事前に選択されています。将来的に、ジオメトリーを選択できるようになる可能性があります。

-s <N>
-s +<N>
Use the --size (or -s) option to choose the size of the output image.

If this option is not given, then the output image will be just large enough to contain all the files, with not much wasted space.

To choose a fixed size output disk, specify an absolute number followed by b/K/M/G/T/P/E to mean bytes, Kilobytes, Megabytes, Gigabytes, Terabytes, Petabytes or Exabytes. This must be large enough to contain all the input files, else you will get an error.

To leave extra space, specify "+" (plus sign) and a number followed by b/K/M/G/T/P/E to mean bytes, Kilobytes, Megabytes, Gigabytes, Terabytes, Petabytes or Exabytes. For example: --size=+200M means enough space for the input files, and (approximately) an extra 200 MB free space.

Note that virt-make-fs estimates free space, and therefore will not produce filesystems containing precisely the free space requested. (It is much more expensive and time-consuming to produce a filesystem which has precisely the desired free space).

-F <fmt>

デフォルトは "raw" です (スパースな raw 形式のディスクイメージ)。

-t <fs>

デフォルトは "ext2" です。

Any filesystem which is supported read-write by libguestfs can be used here.

Set the filesystem label.
このフラグが指定されていると、出力ディスクイメージに MBR パーティションテーブルを追加します。

You can change the partition table type, eg. --partition=gpt for large disks.

For MBR, virt-make-fs sets the partition type byte automatically.

Enable libguestfs trace.


Richard W.M. Jones


Copyright (C) 2010-2016 Red Hat Inc.



To get a list of bugs against libguestfs, use this link:

To report a new bug against libguestfs, use this link:

When reporting a bug, please supply:

  • The version of libguestfs.
  • Where you got libguestfs (eg. which Linux distro, compiled from source, etc)
  • Describe the bug accurately and give a way to reproduce it.
  • Run libguestfs-test-tool(1) and paste the complete, unedited output into the bug report.