[Gluster-devel] Gluster internals

[Anand Avati]

On Mon, May 21, 2012 at 5:40 PM, Ian Latter <ian.latter at midnightcode.org>wrote:

>
> But they include an assumption.
>
> The query is: are async writes and reads sequential?  The
> two specific cases are;
>
>  1) Are all reads that are initiated in time after a write
>      guaranteed to occur after that write has taken affect?
>

Yes


>
>  2) Are all writes that are initiated in time after a write (x)
>      guaranteed to occur after that write (x) has taken
>      affect?
>

Only overlapping offsets/regions retain causal ordering of completion. It
is write-behind which acknowledges writes pre-maturely and therefore the
layer which must maintain the 'effects' for further reads and writes by
making the dependent IOs (overlapping offset/regions) wait for previous
write's actual completion.

Avati
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