{"id":285,"date":"2018-03-13T10:19:03","date_gmt":"2018-03-13T02:19:03","guid":{"rendered":"http:\/\/www.max-shu.com\/blog\/?p=285"},"modified":"2018-03-13T10:19:03","modified_gmt":"2018-03-13T02:19:03","slug":"qemu-img%e4%bd%bf%e7%94%a8%e5%b8%ae%e5%8a%a9","status":"publish","type":"post","link":"http:\/\/www.max-shu.com\/blog\/?p=285","title":{"rendered":"qemu-img\u4f7f\u7528\u5e2e\u52a9"},"content":{"rendered":"
\u4f8b\u5b50\uff1a<\/span><\/b><\/div>\n
# qemu-img info f16-x86_64-openstack-sda.qcow2
\nimage: f16-x86_64-openstack-sda.qcow2
\nfile format: qcow2
\nvirtual size:\u00a09.8G<\/span>\u00a0(10486808576 bytes)
\ndisk size:\u00a0204M<\/span>
\ncluster_size: 65536<\/div>\n
<\/div>\n
\n

qemu-img(1) – Linux man page<\/h1>\n

Name<\/h2>\n

qemu-img\u00a0–\u00a0QEMU\u00a0disk image utility<\/p>\n

Synopsis<\/h2>\n

usage:\u00a0qemu-img\u00a0command [command options]<\/p>\n

Options<\/h2>\n

The following commands are supported:<\/p>\n

\n
check [-f<\/b>\u00a0fmt<\/i>]<\/b>\u00a0filename<\/i><\/dt>\n
create [-f<\/b>\u00a0fmt<\/i>] [-o<\/b>\u00a0options<\/i>]<\/b>\u00a0filename<\/i>\u00a0[<\/b>size<\/i>]<\/b><\/dt>\n
commit [-f<\/b>\u00a0fmt<\/i>]<\/b>\u00a0filename<\/i><\/dt>\n
convert [-c] [-f<\/b>\u00a0fmt<\/i>] [-O<\/b>\u00a0output_fmt<\/i>] [-o<\/b>\u00a0options<\/i>]<\/b>\u00a0filename<\/i>\u00a0[<\/b>filename2<\/i>\u00a0[…]]<\/b>\u00a0output_filename<\/i><\/dt>\n
info\u00a0[-f<\/b>\u00a0fmt<\/i>]<\/b>\u00a0filename<\/i><\/dt>\n
snapshot [-l | -a<\/b>\u00a0snapshot<\/i>\u00a0| -c<\/b>\u00a0snapshot<\/i>\u00a0| -d<\/b>\u00a0snapshot<\/i>]<\/b>\u00a0filename<\/i><\/dt>\n
rebase [-f<\/b>\u00a0fmt<\/i>] [-u] -b<\/b>\u00a0backing_file<\/i>\u00a0[-F<\/b>\u00a0backing_fmt<\/i>]<\/b>\u00a0filename<\/i><\/dt>\n
resize<\/b>\u00a0filename<\/i>\u00a0[+ | -]<\/b>size<\/i><\/dt>\n
Command parameters:<\/dt>\n
filename<\/i><\/dt>\n
\n
is a disk image filename<\/pre>\n<\/dd>\n
fmt<\/i>
\nis the disk image format. It is guessed automatically in most cases. See below for a description of the supported disk formats.<\/dt>\n
size<\/i><\/dt>\n
is the disk image size in bytes. Optional suffixes\u00a0\"k\"<\/tt>\u00a0or\u00a0\"K\"<\/tt>\u00a0(kilobyte, 1024)\u00a0\"M\"<\/tt>\u00a0(megabyte, 1024k) and\u00a0\"G\"<\/tt>\u00a0(gigabyte, 1024M) and T (terabyte, 1024G) are supported.\u00a0\"b\"<\/tt>\u00a0is ignored.<\/dd>\n
output_filename<\/i><\/dt>\n
is the destination disk image filename<\/dd>\n
output_fmt<\/i><\/dt>\n
\n
is the destination format<\/pre>\n<\/dd>\n
options<\/i><\/dt>\n
is a comma separated list of format specific options in a name=value format. Use\u00a0\"-o ?\"<\/tt>\u00a0for an overview of the options supported by the used format or see the format descriptions below for details.<\/dd>\n
-c<\/i>
\nindicates that target image must be compressed (qcow format only)<\/p>\n
-h<\/i><\/p>\n
with or without a command shows help and lists the supported formats<\/dt>\n
Parameters to snapshot subcommand:<\/dt>\n
snapshot<\/b><\/dt>\n
is the name of the snapshot to create, apply or delete<\/dd>\n
-a<\/b>
\napplies a snapshot (revert disk to saved state)<\/p>\n
-c<\/b><\/p>\n
creates a snapshot<\/p>\n
-d<\/b><\/p>\n
deletes a snapshot<\/p>\n
-l<\/b><\/p>\n
lists all snapshots in the given image<\/dt>\n
Command description:<\/dt>\n
create [-f<\/b>\u00a0fmt<\/i>] [-o<\/b>\u00a0options<\/i>]<\/b>\u00a0filename<\/i>\u00a0[<\/b>size<\/i>]<\/b><\/dt>\n
Create the new disk image\u00a0filename<\/i>\u00a0of size\u00a0size<\/i>\u00a0and format\u00a0fmt<\/i>. Depending on the file format, you can add one or more\u00a0options<\/i>\u00a0that enable additional features of this format.If the option\u00a0backing_file<\/i>\u00a0is specified, then the image will record only the differences from\u00a0backing_file<\/i>. No size needs to be specified in this case.\u00a0backing_file<\/i>\u00a0will never be modified unless you use the\u00a0\"commit\"<\/tt>\u00a0monitor command (or\u00a0qemu-img\u00a0commit).<\/p>\n
The size can also be specified using the\u00a0size<\/i>\u00a0option with\u00a0\"-o\"<\/tt>, it doesn’t need to be specified separately in this case.<\/dd>\n
commit [-f<\/b>\u00a0fmt<\/i>]<\/b>\u00a0filename<\/i><\/dt>\n
Commit the changes recorded in\u00a0filename<\/i>\u00a0in its base image.<\/dd>\n
convert [-c] [-f<\/b>\u00a0fmt<\/i>] [-O<\/b>\u00a0output_fmt<\/i>] [-o<\/b>\u00a0options<\/i>]<\/b>\u00a0filename<\/i>\u00a0[<\/b>filename2<\/i>\u00a0[…]]<\/b>\u00a0output_filename<\/i><\/dt>\n
Convert the disk image\u00a0filename<\/i>\u00a0to disk image\u00a0output_filename<\/i>\u00a0using format\u00a0output_fmt<\/i>. It can be optionally compressed (\"-c\"<\/tt>\u00a0option) or use any format specific options like encryption (\"-o\"<\/tt>\u00a0option).Only the formats\u00a0\"qcow\"<\/tt>\u00a0and\u00a0\"qcow2\"<\/tt>\u00a0support compression. The compression is read-only. It means that if a compressed sector is rewritten, then it is rewritten as uncompressed data.<\/p>\n
Image conversion is also useful to get smaller image when using a growable format such as\u00a0\"qcow\"<\/tt>\u00a0or\u00a0\"cow\"<\/tt>: the empty sectors are detected and suppressed from the destination image.<\/p>\n
You can use the\u00a0backing_file<\/i>\u00a0option to force the output image to be created as a copy on write image of the specified base image; the\u00a0backing_file<\/i>\u00a0should have the same content as the input’s base image, however the path, image format, etc may differ.<\/dd>\n
info\u00a0[-f<\/b>\u00a0fmt<\/i>]<\/b>\u00a0filename<\/i><\/dt>\n
Give information about the disk image\u00a0filename<\/i>. Use it in particular to know the size reserved on disk which can be different from the displayed size. If\u00a0VM<\/small>\u00a0snapshots are stored in the disk image, they are displayed too.<\/dd>\n
snapshot [-l | -a<\/b>\u00a0snapshot<\/i>\u00a0| -c<\/b>\u00a0snapshot<\/i>\u00a0| -d<\/b>\u00a0snapshot<\/i>\u00a0]<\/b>\u00a0filename<\/i><\/dt>\n
List, apply, create or delete snapshots in image\u00a0filename<\/i>.<\/dd>\n
resize<\/b>\u00a0filename<\/i>\u00a0[+ | -]<\/b>size<\/i><\/dt>\n
Change the disk image as if it had been created with\u00a0size<\/i>.Before using this command to shrink a disk image, you\u00a0MUST<\/small>\u00a0use file system and partitioning tools inside the\u00a0VM<\/small>\u00a0to reduce allocated file systems and partition sizes accordingly. Failure to do so will result in data loss!<\/p>\n
After using this command to grow a disk image, you must use file system and partitioning tools inside the\u00a0VM<\/small>\u00a0to actually begin using the new space on the device.<\/dd>\n
Supported image file formats:<\/dt>\n
raw<\/b>
\nRaw disk image format (default). This format has the advantage of being simple and easily exportable to all other emulators. If your file system supports\u00a0holes<\/i>\u00a0(for example in ext2 or ext3 on Linux or\u00a0NTFS<\/small>\u00a0on Windows), then only the written sectors will reserve space. Use\u00a0\"qemu-img\u00a0info\"<\/tt>\u00a0to know the real size used by the image or\u00a0\"ls -ls\"<\/tt>\u00a0on Unix\/Linux.<\/dt>\n
host_device<\/b><\/dt>\n
Host device format. This format should be used instead of raw when converting to block devices or other devices where “holes” are not supported.<\/dd>\n
qcow2<\/b><\/dt>\n
QEMU<\/small>\u00a0image format, the most versatile format. Use it to have smaller images (useful if your filesystem does not supports holes, for example on Windows), optional\u00a0AES<\/small>\u00a0encryption, zlib based compression and support of multiple\u00a0VM<\/small>\u00a0snapshots.Supported options:<\/dd>\n
“backing_file”<\/dd>\n
File name of a base image (see\u00a0create<\/b>\u00a0subcommand)<\/dd>\n
“backing_fmt”<\/dd>\n
Image format of the base image<\/dd>\n
“encryption”<\/dd>\n
If this option is set to\u00a0\"on\"<\/tt>, the image is encrypted.Encryption uses the\u00a0AES<\/small>\u00a0format which is very secure (128 bit keys). Use a long password (16 characters) to get maximum protection.<\/dd>\n
“cluster_size”<\/dd>\n
Changes the qcow2 cluster size (must be between 512 and 2M). Smaller cluster sizes can improve the image file size whereas larger cluster sizes generally provide better performance.<\/dd>\n
“preallocation”<\/dd>\n
Preallocation mode (allowed values: off, metadata). An image with preallocated metadata is initially larger but can improve performance when the image needs to grow.<\/dd>\n
qcow<\/b><\/dt>\n
Old\u00a0QEMU<\/small>\u00a0image format. Left for compatibility.Supported options:<\/dd>\n
“backing_file”<\/dd>\n
File name of a base image (see\u00a0create<\/b>\u00a0subcommand)<\/dd>\n
“encryption”<\/dd>\n
If this option is set to\u00a0\"on\"<\/tt>, the image is encrypted.<\/dd>\n
cow<\/b>
\nUser Mode Linux Copy On Write image format. Used to be the only growable image format in\u00a0QEMU<\/small>\u00a0. It is supported only for compatibility with previous versions. It does not work on win32.<\/p>\n
vdi<\/b><\/p>\n
VirtualBox 1.1 compatible image format.<\/dt>\n
vmdk<\/b><\/dt>\n
VMware 3 and 4 compatible image format.Supported options:<\/dd>\n
“backing_fmt”<\/dd>\n
Image format of the base image<\/dd>\n
“compat6”<\/dd>\n
Create a\u00a0VMDK<\/small>\u00a0version 6 image (instead of version 4)<\/dd>\n
vpc<\/b>
\nVirtualPC compatible image format (\u00a0VHD<\/small>\u00a0).<\/dt>\n
cloop<\/b><\/dt>\n
Linux Compressed Loop image, useful only to reuse directly compressed CD-ROM images present for example in the Knoppix CD-ROMs.<\/dd>\n<\/dl>\n
See Also<\/h2>\n
The\u00a0HTML<\/small>\u00a0documentation of\u00a0QEMU<\/small>\u00a0for more precise information and Linux user mode emulator invocation.<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"
\u4f8b\u5b50\uff1a # qemu-img info f16-x86_64-openstack-sda.qcow2 imag …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[227,218,228,229,151],"class_list":["post-285","post","type-post","status-publish","format-standard","hentry","category-4","tag-img","tag-qemu","tag-qemu-img","tag-229","tag-151"],"views":2107,"_links":{"self":[{"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/285","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=285"}],"version-history":[{"count":1,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/285\/revisions"}],"predecessor-version":[{"id":286,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/285\/revisions\/286"}],"wp:attachment":[{"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=285"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=285"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.max-shu.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=285"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}