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Date: Mon, 17 Apr 2017 11:49:25 +0800
From: Fam Zheng <famz@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v6] migration/block: use blk_pwrite_zeroes
 for each zero cluster
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To: 858585 jemmy <jemmy858585@gmail.com>
Cc: qemu-block@nongnu.org, quintela@redhat.com, dgilbert@redhat.com, qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>, Lidong Chen <lidongchen@tencent.com>

On Fri, 04/14 14:30, 858585 jemmy wrote:
> Do you know some other format which have very small cluster size?

64k is the default cluster size for qcow2 but it can be configured at image
creation time, as 512 bytes, for example:

    $ qemu-img create -f qcow2 test.qcow2 -o cluster_size=512 1G

Fam