Distributed Replicated Block Device (DRBD) development
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From: Philipp Reisner <philipp.reisner@linbit.com>
To: drbd-dev@lists.linbit.com
Subject: Re: [Drbd-dev] How Locking in GFS works...
Date: Fri, 8 Oct 2004 15:37:23 +0200	[thread overview]
Message-ID: <200410081537.23086.philipp.reisner@linbit.com> (raw)
In-Reply-To: <20041008125544.GO8249@marowsky-bree.de>

Am Freitag, 8. Oktober 2004 14:55 schrieb Lars Marowsky-Bree:
> On 2004-10-08T14:32:09, Philipp Reisner <philipp.reisner@linbit.com> wrote:
> >   3. Concurrent writes, high latency for data packets.
> >     The problem now is that N2 does can not detect that this was
> >     a concurrent write, since it got the ACK before the conflicting
> >     data packets comes in.
>
> Uhm. I don't see how this can be a problem.
>
> In this case, one write has logically happened before the other, and
> from they don't overlap - the second write will simply wipe out the
> first one, which seems fine?
>

Just look at it again. on the left figure you will find that N1 has
the blue data on its block and N2 has the green data on its disk. 

I do see here a problem.

> >   5. New write while processing a write from the peer.
>
> Sounds just like case 1.
>

In case 1 there is no concurrenct access at all ?!?

Hav you had a look at the pdf ?

-Philipp

  reply	other threads:[~2004-10-08 13:37 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-10-04 12:56 [Drbd-dev] How Locking in GFS works Philipp Reisner
2004-10-04 13:01 ` Lars Marowsky-Bree
2004-10-04 13:20   ` Lars Ellenberg
2004-10-04 13:41     ` Lars Marowsky-Bree
2004-10-04 13:26   ` Philipp Reisner
2004-10-04 13:49     ` Lars Marowsky-Bree
2004-10-04 14:09       ` Philipp Reisner
2004-10-04 14:17         ` Philipp Reisner
2004-10-04 15:12           ` Lars Ellenberg
2004-10-04 20:24             ` Lars Marowsky-Bree
2004-10-08 12:32             ` Philipp Reisner
2004-10-08 12:55               ` Lars Marowsky-Bree
2004-10-08 13:37                 ` Philipp Reisner [this message]
2004-10-08 13:51               ` Lars Ellenberg
2004-10-11  7:12                 ` Philipp Reisner
2004-10-11 10:09                   ` Lars Ellenberg
2004-10-11 10:11                   ` Lars Ellenberg
2004-10-11 12:28                     ` Philipp Reisner
2004-10-11 12:41                       ` Philipp Reisner
2004-10-05 19:37           ` Philipp Reisner
2004-10-05 19:39             ` Philipp Reisner

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