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| -rw-r--r-- | qemu-img.texi | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/qemu-img.texi b/qemu-img.texi index 5a7b2bb1f2..77c6d0b6b0 100644 --- a/qemu-img.texi +++ b/qemu-img.texi @@ -237,6 +237,29 @@ to grow. @end table +@item qed +Image format with support for backing files and compact image files (when your +filesystem or transport medium does not support holes). Good performance due +to less metadata than the more featureful qcow2 format, especially with +cache=writethrough or cache=directsync. Consider using qcow2 which will soon +have a similar optimization and is most actively developed. + +Supported options: +@table @code +@item backing_file +File name of a base image (see @option{create} subcommand). +@item backing_fmt +Image file format of backing file (optional). Useful if the format cannot be +autodetected because it has no header, like some vhd/vpc files. +@item cluster_size +Changes the cluster size (must be power-of-2 between 4K and 64K). Smaller +cluster sizes can improve the image file size whereas larger cluster sizes +generally provide better performance. +@item table_size +Changes the number of clusters per L1/L2 table (must be power-of-2 between 1 +and 16). There is normally no need to change this value but this option can be +used for performance benchmarking. +@end table @item qcow Old QEMU image format. Left for compatibility. |