From: Eric Blake <eblake@redhat.com>
To: "Benoît Canet" <benoit.canet@gmail.com>
Cc: kwolf@redhat.com, "Benoît Canet" <benoit@irqsave.net>,
qemu-devel@nongnu.org, blauwirbel@gmail.com, pbonzini@redhat.com,
stefanha@linux.vnet.ibm.com
Subject: Re: [Qemu-devel] [RFC V5 09/11] quorum: Add quorum_getlength().
Date: Mon, 27 Aug 2012 12:03:48 -0600 [thread overview]
Message-ID: <503BB684.5000007@redhat.com> (raw)
In-Reply-To: <1346052629-15686-10-git-send-email-benoit@irqsave.net>
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On 08/27/2012 01:30 AM, Benoît Canet wrote:
> Signed-off-by: Benoit Canet <benoit@irqsave.net>
> ---
> block/quorum.c | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
Say I'm using a 2/3 quorum. What happens if:
image A and B agree on initial content, but not length
image B and C agree on length, but not content
Does disagreeing with quorum consensus invalidate that member of the
quorum from influencing further decisions? If there is a length
discrepancy, should we declare the quorum failed rather than relying on
a mere majority vote? Or, if there is a length discrepancy, does
reading the contents beyond the end of the shorter files consider the
contents to be okay if the longer files have only NUL bytes in the extra
length? I'm worried that you haven't fully thought through all the
scenarios here.
--
Eric Blake eblake@redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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next prev parent reply other threads:[~2012-08-27 18:04 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-27 7:30 [Qemu-devel] [RFC V5 00/11] Quorum disk image corruption resiliency Benoît Canet
2012-08-27 7:30 ` [Qemu-devel] [RFC V5 01/11] quorum: Create quorum.c, add QuorumSingleAIOCB and QuorumAIOCB Benoît Canet
2012-08-27 7:30 ` [Qemu-devel] [RFC V5 02/11] quorum: Create BDRVQuorumState and BlkDriver and do init Benoît Canet
2012-08-27 7:30 ` [Qemu-devel] [RFC V5 03/11] quorum: Add quorum_open() and quorum_close() Benoît Canet
2012-08-27 17:59 ` Eric Blake
2012-08-27 19:20 ` Benoît Canet
2012-08-27 7:30 ` [Qemu-devel] [RFC V5 04/11] quorum: Add quorum_aio_writev and its dependencies Benoît Canet
2012-08-27 7:30 ` [Qemu-devel] [RFC V5 05/11] blkverify: Extract qemu_iovec_clone() and qemu_iovec_compare() from blkverify Benoît Canet
2012-08-27 7:30 ` [Qemu-devel] [RFC V5 06/11] quorum: Add quorum_co_flush() Benoît Canet
2012-08-27 7:30 ` [Qemu-devel] [RFC V5 07/11] quorum: Add quorum_aio_readv Benoît Canet
2012-08-27 7:30 ` [Qemu-devel] [RFC V5 08/11] quorum: Add quorum mechanism Benoît Canet
2012-08-27 7:30 ` [Qemu-devel] [RFC V5 09/11] quorum: Add quorum_getlength() Benoît Canet
2012-08-27 18:03 ` Eric Blake [this message]
2012-08-27 19:23 ` Benoît Canet
2012-08-27 7:30 ` [Qemu-devel] [RFC V5 10/11] quorum: Add quorum_invalidate_cache() Benoît Canet
2012-08-27 7:30 ` [Qemu-devel] [RFC V5 11/11] quorum: Add quorum_co_is_allocated Benoît Canet
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