Re : Replication factor for system_auth keyspace

[sai krishnam raju potturi <ps...@gmail.com>]

hi;
  we are deploying a new cluster with 2 datacenters, 48 nodes in each DC.
For the system_auth keyspace, what should be the ideal replication_factor
set?

We tried setting the replication factor equal to the number of nodes in a
datacenter, and the repair for the system_auth keyspace took really long.
Your suggestions would be of great help.

thanks
Sai

Re: Re : Replication factor for system_auth keyspace

[sai krishnam raju potturi <ps...@gmail.com>]

thanks guys for the advice. We were running parallel repairs earlier, with
cassandra version 2.0.14. As pointed out having set the replication factor
really huge for system_auth was causing the repair to take really long.

thanks
Sai

On Fri, Oct 16, 2015 at 9:56 AM, Victor Chen <vi...@gmail.com>
wrote:

> To elaborate on what Robert said, I think with most things technology
> related, the answer with these sorts of questions (i.e. "ideal settings")
> is usually "it depends." Remember that technology is a tool that we use to
> accomplish something we want. It's just a mechanism that we as humans use
> to exert our wishes on other things. In this case, cassandra allows us to
> exert our wishes on the data we need to have available. So think for a
> second about what you want? To be less philosophical and more practical,
> how many nodes you are comfortable losing or likely to lose? How many
> copies of your system_auth keyspace do you want to have always available?
>
> Also, what do you mean by "really long?" What version of cassandra are you
> using? If you are on 2.1, look at migrating to incremental repair. That it
> takes so long for such a small keyspace leads me to believe you're using
> sequential repair ...
>
> -V
>
> On Thu, Oct 15, 2015 at 7:46 PM, Robert Coli <rc...@eventbrite.com> wrote:
>
>> On Thu, Oct 15, 2015 at 10:24 AM, sai krishnam raju potturi <
>> pskraju88@gmail.com> wrote:
>>
>>>   we are deploying a new cluster with 2 datacenters, 48 nodes in each
>>> DC. For the system_auth keyspace, what should be the ideal
>>> replication_factor set?
>>>
>>> We tried setting the replication factor equal to the number of nodes in
>>> a datacenter, and the repair for the system_auth keyspace took really long.
>>> Your suggestions would be of great help.
>>>
>>
>> More than 1 and a lot less than 48.
>>
>> =Rob
>>
>>
>

Re: Re : Replication factor for system_auth keyspace

[Victor Chen <vi...@gmail.com>]

To elaborate on what Robert said, I think with most things technology
related, the answer with these sorts of questions (i.e. "ideal settings")
is usually "it depends." Remember that technology is a tool that we use to
accomplish something we want. It's just a mechanism that we as humans use
to exert our wishes on other things. In this case, cassandra allows us to
exert our wishes on the data we need to have available. So think for a
second about what you want? To be less philosophical and more practical,
how many nodes you are comfortable losing or likely to lose? How many
copies of your system_auth keyspace do you want to have always available?

Also, what do you mean by "really long?" What version of cassandra are you
using? If you are on 2.1, look at migrating to incremental repair. That it
takes so long for such a small keyspace leads me to believe you're using
sequential repair ...

-V

On Thu, Oct 15, 2015 at 7:46 PM, Robert Coli <rc...@eventbrite.com> wrote:

> On Thu, Oct 15, 2015 at 10:24 AM, sai krishnam raju potturi <
> pskraju88@gmail.com> wrote:
>
>>   we are deploying a new cluster with 2 datacenters, 48 nodes in each DC.
>> For the system_auth keyspace, what should be the ideal replication_factor
>> set?
>>
>> We tried setting the replication factor equal to the number of nodes in a
>> datacenter, and the repair for the system_auth keyspace took really long.
>> Your suggestions would be of great help.
>>
>
> More than 1 and a lot less than 48.
>
> =Rob
>
>

Re: Re : Replication factor for system_auth keyspace

[Robert Coli <rc...@eventbrite.com>]

On Thu, Oct 15, 2015 at 10:24 AM, sai krishnam raju potturi <
pskraju88@gmail.com> wrote:

>   we are deploying a new cluster with 2 datacenters, 48 nodes in each DC.
> For the system_auth keyspace, what should be the ideal replication_factor
> set?
>
> We tried setting the replication factor equal to the number of nodes in a
> datacenter, and the repair for the system_auth keyspace took really long.
> Your suggestions would be of great help.
>

More than 1 and a lot less than 48.

=Rob