[Gluster-users] Read from fastest node only

[David Cunningham]

Hi Ravi and Strahil,

Thanks again for your responses. Having one brick be the one to read (but
with failover if that node goes completely offline) would be great if we
could do it per client, but won't work if all clients have to use the same
setting.

I'm not sure about gNFS, but normal NFS is something we've thought about as
an option. I'm not sure if it will help though, because if the client NFS
mounts the server which has the brick, then when it does a read presumably
the brick will be checked for consistency with the other bricks and latency
will be a problem again. If my understanding is correct even with
choose-local enabled the other bricks will still be checked so the problem
is not solved.

I confess that AFR vs eventual consistency is beyond my understanding of
replication. In the world of SQL there is Galera cluster, and it will write
to all nodes but for reads only checks the node the client is actually
connected to. That's the sort of functionality we'd find really helpful for
our use-case.


On Fri, 30 Jul 2021 at 19:21, Strahil Nikolov <hunter86_bg at yahoo.com> wrote:

> Hi David,
>
> md-cache will just save some lookup actions across the bricks, but it
> won't save you from all cases.
>
> Using gNFS + cluster.choose-local is worth exploring, but as gNFS is
> deprecated I never checked if it will be affected by the lattency of the
> last brick.
>
> What Ravi proposed looks promising, but it has some drawbacks - for
> example a brick dies and FUSE clienta have to be adjusted to read from
> another brick.
>
> Ravi, I think that this topic was already discussed once.
>
> Best Regards,
> Strahil Nikolov
>
> On Fri, Jul 30, 2021 at 8:49, Ravishankar N
> <ranaraya at redhat.com> wrote:
> ________
>
>
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David Cunningham, Voisonics Limited
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