Re: [Qemu-devel] [PATCH v2 08/12] mirror: allow customizing the granularity

[Eric Blake]

On 01/16/2013 10:31 AM, Paolo Bonzini wrote:
> The desired granularity may be very different depending on the kind of
> operation (e.g. continuous replication vs. collapse-to-raw) and whether
> the VM is expected to perform lots of I/O while mirroring is in progress.
> 
> Allow the user to customize it, while providing a sane default so that
> in general there will be no extra allocated space in the target compared
> to the source.
> 

> +++ b/qapi-schema.json
> @@ -1636,6 +1636,11 @@
>  #        (all the disk, only the sectors allocated in the topmost image, or
>  #        only new I/O).
>  #
> +# @granularity: #optional granularity of the dirty bitmap, default is 64K
> +#               if the image format doesn't have clusters, 4K if the clusters
> +#               are smaller than that, else the cluster size.  Must be a
> +#               power of 2 between 512 and 64M.

Mention that granularity was only added in 1.4.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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