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Re: [Qemu-devel] [RFC PATCH 01/14] docs: block replication's description
From: |
Fam Zheng |
Subject: |
Re: [Qemu-devel] [RFC PATCH 01/14] docs: block replication's description |
Date: |
Thu, 12 Feb 2015 15:21:17 +0800 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
Hi Congyang,
On Thu, 02/12 11:07, Wen Congyang wrote:
> +== Workflow ==
> +The following is the image of block replication workflow:
> +
> + +----------------------+ +------------------------+
> + |Primary Write Requests| |Secondary Write Requests|
> + +----------------------+ +------------------------+
> + | |
> + | (4)
> + | V
> + | /-------------\
> + | Copy and Forward | |
> + |---------(1)----------+ | Disk Buffer |
> + | | | |
> + | (3) \-------------/
> + | speculative ^
> + | write through (2)
> + | | |
> + V V |
> + +--------------+ +----------------+
> + | Primary Disk | | Secondary Disk |
> + +--------------+ +----------------+
> +
> + 1) Primary write requests will be copied and forwarded to Secondary
> + QEMU.
> + 2) Before Primary write requests are written to Secondary disk, the
> + original sector content will be read from Secondary disk and
> + buffered in the Disk buffer, but it will not overwrite the existing
> + sector content in the Disk buffer.
I'm a little confused by the tenses ("will be" versus "are") and terms. I am
reading them as "s/will be/are/g"
Why do you need this buffer?
If both primary and secondary write to the same sector, what is saved in the
buffer?
Fam
> + 3) Primary write requests will be written to Secondary disk.
> + 4) Secondary write requests will be buffered in the Disk buffer and it
> + will overwrite the existing sector content in the buffer.
> +
- [Qemu-devel] [RFC PATCH 00/14] Block replication for continuous checkpoints, Wen Congyang, 2015/02/11
- [Qemu-devel] [RFC PATCH 02/14] quorom: add a new read pattern, Wen Congyang, 2015/02/11
- [Qemu-devel] [RFC PATCH 01/14] docs: block replication's description, Wen Congyang, 2015/02/11
- Re: [Qemu-devel] [RFC PATCH 01/14] docs: block replication's description,
Fam Zheng <=
- Re: [Qemu-devel] [RFC PATCH 01/14] docs: block replication's description, Wen Congyang, 2015/02/12
- Re: [Qemu-devel] [RFC PATCH 01/14] docs: block replication's description, Fam Zheng, 2015/02/12
- Re: [Qemu-devel] [RFC PATCH 01/14] docs: block replication's description, Wen Congyang, 2015/02/12
- Re: [Qemu-devel] [RFC PATCH 01/14] docs: block replication's description, Fam Zheng, 2015/02/12
- Re: [Qemu-devel] [RFC PATCH 01/14] docs: block replication's description, Wen Congyang, 2015/02/12
- Re: [Qemu-devel] [RFC PATCH 01/14] docs: block replication's description, famz, 2015/02/12
- Re: [Qemu-devel] [RFC PATCH 01/14] docs: block replication's description, Wen Congyang, 2015/02/13
- Re: [Qemu-devel] [RFC PATCH 01/14] docs: block replication's description, Fam Zheng, 2015/02/13
- Re: [Qemu-devel] [RFC PATCH 01/14] docs: block replication's description, John Snow, 2015/02/13
- Re: [Qemu-devel] [RFC PATCH 01/14] docs: block replication's description, Hongyang Yang, 2015/02/12