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Posted to dev@cassandra.apache.org by Sumanth Pasupuleti <su...@gmail.com> on 2020/05/13 19:01:34 UTC
Scope of CASSANDRA-14557 (Default and Minimum RF)
Hi,
Based on Alex's suggestion on the ticket, wanted to reach out to clarify on
the current scope of default and minimum replication factors that 14557
defines, and gather thoughts to farm for dissent.
Both the configurations (default and minimum) apply not just to user
keyspaces, but also to system keyspaces. For instance, this can be handy in
deployments that use authenticated C* clusters where operators have to
"remember" to set system_auth keyspace's RF to a value higher than 1. In
such cases, setting default_rf = 3 for example (which I suppose is common
in most deployments) would ensure all the system keyspaces (including
system_auth) come up with RF=3.
It can be helpful to note that, this patch by default does not cause any
change to the replication factors, reason being, the default values of
these configurations are set to [defaultRF=1, minimumRF=0] to not induce
any changes that folks may not expect, but rather offers knobs to define
what a sane default RF should be, and have a gate on any new keyspaces
being created with an RF lower than minimumRF.
Curious to know your thoughts.
Thanks,
Sumanth
Re: Scope of CASSANDRA-14557 (Default and Minimum RF)
Posted by Sumanth Pasupuleti <su...@gmail.com>.
I agree. I've updated the patch in 14557 to include a note about
application to system keyspaces in cassandra.yaml.
On Mon, May 18, 2020 at 1:59 AM Oleksandr Petrov <ol...@gmail.com>
wrote:
> I think it is reasonable that system keyspaces would get initialized with a
> default replication factor, assuming ones that were already
> initalized would remain intact (however, this should be the same for
> user-created keyspaces).
>
> Assuming it doesn't change the current behaviour, and default and min rf,
> when unset, act the same way current version would, the only thing we
> should probably add is a line in cassandra.conf that default and min
> replication factors will also apply to system keyspaces.
>
> On Wed, May 13, 2020 at 9:01 PM Sumanth Pasupuleti <
> sumanth.pasupuleti.is@gmail.com> wrote:
>
> > Hi,
> >
> > Based on Alex's suggestion on the ticket, wanted to reach out to clarify
> on
> > the current scope of default and minimum replication factors that 14557
> > defines, and gather thoughts to farm for dissent.
> >
> > Both the configurations (default and minimum) apply not just to user
> > keyspaces, but also to system keyspaces. For instance, this can be handy
> in
> > deployments that use authenticated C* clusters where operators have to
> > "remember" to set system_auth keyspace's RF to a value higher than 1. In
> > such cases, setting default_rf = 3 for example (which I suppose is common
> > in most deployments) would ensure all the system keyspaces (including
> > system_auth) come up with RF=3.
> >
> > It can be helpful to note that, this patch by default does not cause any
> > change to the replication factors, reason being, the default values of
> > these configurations are set to [defaultRF=1, minimumRF=0] to not induce
> > any changes that folks may not expect, but rather offers knobs to define
> > what a sane default RF should be, and have a gate on any new keyspaces
> > being created with an RF lower than minimumRF.
> >
> > Curious to know your thoughts.
> >
> > Thanks,
> > Sumanth
> >
>
>
> --
> alex p
>
Re: Scope of CASSANDRA-14557 (Default and Minimum RF)
Posted by Oleksandr Petrov <ol...@gmail.com>.
I think it is reasonable that system keyspaces would get initialized with a
default replication factor, assuming ones that were already
initalized would remain intact (however, this should be the same for
user-created keyspaces).
Assuming it doesn't change the current behaviour, and default and min rf,
when unset, act the same way current version would, the only thing we
should probably add is a line in cassandra.conf that default and min
replication factors will also apply to system keyspaces.
On Wed, May 13, 2020 at 9:01 PM Sumanth Pasupuleti <
sumanth.pasupuleti.is@gmail.com> wrote:
> Hi,
>
> Based on Alex's suggestion on the ticket, wanted to reach out to clarify on
> the current scope of default and minimum replication factors that 14557
> defines, and gather thoughts to farm for dissent.
>
> Both the configurations (default and minimum) apply not just to user
> keyspaces, but also to system keyspaces. For instance, this can be handy in
> deployments that use authenticated C* clusters where operators have to
> "remember" to set system_auth keyspace's RF to a value higher than 1. In
> such cases, setting default_rf = 3 for example (which I suppose is common
> in most deployments) would ensure all the system keyspaces (including
> system_auth) come up with RF=3.
>
> It can be helpful to note that, this patch by default does not cause any
> change to the replication factors, reason being, the default values of
> these configurations are set to [defaultRF=1, minimumRF=0] to not induce
> any changes that folks may not expect, but rather offers knobs to define
> what a sane default RF should be, and have a gate on any new keyspaces
> being created with an RF lower than minimumRF.
>
> Curious to know your thoughts.
>
> Thanks,
> Sumanth
>
--
alex p