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From: Dietmar Maurer <dietmar@proxmox.com>
Date: Wed, 22 May 2013 15:34:18 +0000
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Subject: Re: [Qemu-devel] [PATCH v3 0/8] block: drive-backup live backup
	command
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To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Fam Zheng <famz@redhat.com>, Stefan Hajnoczi <stefanha@gmail.com>, qemu-devel <qemu-devel@nongnu.org>, "imain@redhat.com" <imain@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Wenchao Xia <xiawenc@linux.vnet.ibm.com>

> That sounds like more work than a persistent dirty bitmap.  The advantage=
 is that
> while dirty bitmaps are consumed by a single user, the Merkle tree can be=
 used
> to sync up any number of replicas.

I also consider it safer, because you make sure the data exists (using hash=
 keys like SHA1).

I am unsure how you can check if a dirty bitmap contains errors, or is out =
of date?

Also, you can compare arbitrary Merkle trees, whereas a dirty bitmap is alw=
ays related to a single image.
(consider the user remove the latest backup from the backup target).=20