Date: Tue, 9 Jun 2015 13:33:05 -0700 (PDT)
From: David Lang <david@lang.hm>
To: David Teigland <teigland@redhat.com>
cc: Goldwyn Rodrigues <rgoldwyn@suse.com>, linux-kernel@vger.kernel.org,
        NeilBrown <neilb@suse.de>
Subject: Re: clustered MD
In-Reply-To: <20150609203056.GB17536@redhat.com>
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References: <20150609182102.GA4305@redhat.com> <55773DE1.7080107@suse.com> <20150609194505.GA17536@redhat.com> <557747AB.7080706@suse.com> <20150609203056.GB17536@redhat.com>
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On Tue, 9 Jun 2015, David Teigland wrote:

>> We do have a valid real world utility. It is to provide
>> high-availability of RAID1 storage  over the cluster. The
>> distributed locking is required only during cases of error and
>> superblock updates and is not required during normal operations,
>> which makes it fast enough for usual case scenarios.
>
> That's the theory, how much evidence do you have of that in practice?
>
>> What are the doubts you have about it?
>
> Before I begin reviewing the implementation, I'd like to better understand
> what it is about the existing raid1 that doesn't work correctly for what
> you'd like to do with it, i.e. I don't know what the problem is.

As I understand things, the problem is ~providing RAID across multiple machines, 
not just across the disks in one machine.

David Lang
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