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Re: [Qemu-devel] Should 'qemu-img commit' sparsify the backing file?
From: |
Richard W.M. Jones |
Subject: |
Re: [Qemu-devel] Should 'qemu-img commit' sparsify the backing file? |
Date: |
Thu, 5 Nov 2015 12:18:59 +0000 |
User-agent: |
Mutt/1.5.20 (2009-12-10) |
On Thu, Nov 05, 2015 at 05:46:01PM +0800, Fam Zheng wrote:
> Does virt-sparsify work if there is no file system present (e.g. the disk is
> fully filled with zeroes) on the device?
It doesn't do anything bad, but it doesn't currently do that. You
could do that using:
guestfish <<EOF
add zeroes.img discard:enable format:raw
run
blkdiscard /dev/sda
EOF
To add this to virt-sparsify, we'd need a different primitive command,
one which only trims blocks that contain zero (blkdiscard trims
everything), which we don't have right now.
Rich.
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