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| author | Fam Zheng | 2018-07-11 03:22:27 +0200 |
|---|---|---|
| committer | Kevin Wolf | 2018-07-12 18:24:08 +0200 |
| commit | eb461485f4558e362fab905735b50987505bca44 (patch) | |
| tree | a28f9385d40bf1efc1f35491a7a09332cc98e900 | |
| parent | iotests: nbd: Stop qemu-nbd before remaking image (diff) | |
| download | qemu-eb461485f4558e362fab905735b50987505bca44.tar.gz qemu-eb461485f4558e362fab905735b50987505bca44.tar.xz qemu-eb461485f4558e362fab905735b50987505bca44.zip | |
qemu-img: Document copy offloading implications with -S and -c
Explicitly enabling zero detection or compression suppresses copy
offloading during convert. Document it.
Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
| -rw-r--r-- | qemu-img.texi | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/qemu-img.texi b/qemu-img.texi index aeb1b9e66c..5853cd18d1 100644 --- a/qemu-img.texi +++ b/qemu-img.texi @@ -96,7 +96,8 @@ will enumerate information about backing files in a disk image chain. Refer below for further description. @item -c -indicates that target image must be compressed (qcow format only) +indicates that target image must be compressed (qcow format only). If this +option is used, copy offloading will not be attempted. @item -h with or without a command shows help and lists the supported formats @@ -115,7 +116,8 @@ in case both @var{-q} and @var{-p} options are used. indicates the consecutive number of bytes that must contain only zeros for qemu-img to create a sparse image during conversion. This value is rounded down to the nearest 512 bytes. You may use the common size suffixes like -@code{k} for kilobytes. +@code{k} for kilobytes. If this option is used, copy offloading will not be +attempted. @item -t @var{cache} specifies the cache mode that should be used with the (destination) file. See |