From: Paolo Bonzini <pbonzini@redhat.com>
To: Alberto Garcia <berto@igalia.com>, Kevin Wolf <kwolf@redhat.com>
Cc: stefanha@redhat.com, qemu-block@nongnu.org, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH for-2.6] block: Forbid I/O throttling on nodes with multiple parents for 2.6
Date: Wed, 6 Apr 2016 18:01:16 +0200 [thread overview]
Message-ID: <570532CC.5090209@redhat.com> (raw)
In-Reply-To: <w511t6ilok4.fsf@maestria.local.igalia.com>
On 06/04/2016 17:55, Alberto Garcia wrote:
>> > [BB] overlay
>> > |
>> > |
>> > [BDS] qcow2 [BB] backing
>> > | |
>> > +--------------------+
>> > . |
>> > . I/O throttling
>> > . |
>> > [BDS] raw
>> > .
>> > .
>> > .
> I see, thanks for the explanation!
>
> But what's the use of having a BlockBackend on a node that is used as a
> backing image? Is it because "we allow this so let's prevent the user
> from doing weird things", or is there anything useful we can do with it?
The backing image can be the one that is visible to the guest, while the
overlay can be a block-backup target (with 'sync':'none) whose
BlockBackend is created by the NBD server.
Paolo
next prev parent reply other threads:[~2016-04-06 16:01 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-04 15:26 [Qemu-devel] [PATCH for-2.6] block: Forbid I/O throttling on nodes with multiple parents for 2.6 Kevin Wolf
2016-04-04 15:32 ` Eric Blake
2016-04-06 9:45 ` Alberto Garcia
2016-04-06 9:59 ` Kevin Wolf
2016-04-06 15:55 ` Alberto Garcia
2016-04-06 16:01 ` Paolo Bonzini [this message]
2016-04-06 19:01 ` Alberto Garcia
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