Re: [PATCH 32/32] kbase: Add document outlining internals of incremental backup in qemu
On Fri, Jun 19, 2020 at 10:10:36 -0500, Eric Blake wrote:
On 6/15/20 12:10 PM, Peter Krempa wrote:
> Outline the basics and how to integrate with externally created
> overlays. Other topics will continue later.
>
> Signed-off-by: Peter Krempa <pkrempa(a)redhat.com>
> ---
> docs/kbase.html.in | 3 +
> docs/kbase/incrementalbackupinternals.rst | 210 ++++++++++++++++++++++
> 2 files changed, 213 insertions(+)
> create mode 100644 docs/kbase/incrementalbackupinternals.rst
[...]
> +Snapshot
> +
> + Similarly to a checkpoint it's a point in time in the lifecycle of the VM
> + but the state of the VM including memory is captured at that point allowing
> + returning to the state later.
Hmm. We have disk-only snapshots which do not save the state of memory. Does
this paragraph need adjustment to mention the difference between a disk-only
snapshot and a full state capture? Are we redefining any of the terms in
domainstatecapture.rst, and/or should those two documents have
cross-references?
Good idea! I'll keep this as is, but I'll link to the
domainstatecapture.rst document at the beginning of the glossary.
[...]
> + fi
> +
> + for BACKING_BITMAP_ in $(jq -c '.[]' <<<
"$BACKING_BITMAPS"); do
> + BITMAP_FLAGS=$(jq -c -r '.flags[]' <<<
"$BACKING_BITMAP_")
> + BITMAP_NAME=$(jq -r '.name' <<<
"$BACKING_BITMAP_")
> +
> + if grep 'in-use' <<< "$BITMAP_FLAGS" ||
> + grep -v 'auto' <<< "$BITMAP_FLAGS"; then
> + continue
> + fi
> +
> + qemu-img bitmap -f "$SNAP_FMT" "$SNAP_IMG" --add
"$BITMAP_NAME"
Do you want to also copy the --granularity of the bitmaps being
added?
Hmm, yeah, that's what libvirt does.