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Bharata B Rao authored
GlusterFS supports creation of zero-filled file on GlusterFS volume by means of an API called glfs_zerofill(). Use this API from QEMU to create an image that is filled with zeroes by using the preallocation option of qemu-img. qemu-img create gluster://server/volume/image -o preallocation=full 10G The allowed values for preallocation are 'full' and 'off'. By default preallocation is off and image is not zero-filled. glfs_zerofill() offloads the writing of zeroes to the server and if the storage supports SCSI WRITESAME, GlusterFS server can issue BLKZEROOUT ioctl to achieve the zeroing. Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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