Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/2] Truncate the tail of the image file in qcow2 shrinking

[Daniel P. Berrange]

On Fri, Sep 22, 2017 at 12:39:24PM +0300, Pavel Butsykin wrote:
> Now after shrinking the qcow2 image, at the end of the image file, there might
> be a tail that probably will never be used. Although it will not bring any
> tangible benefit, we can cut the tail if it is. Yes, it will not free up disk
> space, but if the blocks were be allocated sequentially and the image is not
> heavily fragmented then the virtual size of the image file will be 
> commensurate
> with the real size. It also doesn't look like a great plus.. Well, at least we
> can discuss it.

If the block backend has discard support enabled, can't we get the tail
to be discarded rather than merely truncated ?

Regards,
Daniel
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